MAF
THROTTLE BODY
FUEL INJECTO R
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
MAF
THROTTLE BODY
FUEL INJECTOR
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
Timm's BMW Engines - Diagnostics and Adaptations What are they all about and how to fix engine running problems This is a big subject - engine running problems and adaptations - especially ‘adaptations at limits’ which light up the engine warning lamp. There is loads of advice on the Forums that say ‘you need diagnostics’ - but what do you actually do with diagnostics - and what do all those values mean? This document is for those that have engine running problems and want to fix them with the help of diagnostics - in this case we are using INPA. To get us going we are going to have to understand adaptations first! ADAPTATIONS Looking at the stored adaptation values gives us a good insight into the condition of the engine and the source of the problems you may be having - so we are going to have to understand them first. And to do that we are going to look at a single cylinder of our engines and ignore all the other sensors. All we are interested in is the basic fuel/air mixture which is provided by measuring air MASS (with a MAF sensor) - the ECU (engine computer) then computes how long to open the injector for:
input 1 gram of air per rev output 10ms injector duration
So, above is the very basic plan - measure the air input and decide on how long to open the injector - this happens every camshaft revolution. The target is to get the fuel/air ratio correct because this provides efficient combustion and clean exhaust gasses. But, it is pretty obvious that there are going to be errors, and early engines had an adjustment for the air measuring device (which was an AIRFLOW METER rather than a MAF) so that you could compensate for wear, air leaks, blocked injectors and a myriad of other possibilities. So - engine manufacturers added a way of checking the fuel/air mixture by using a Lambda (Oxygen) sensor. The Lambda (Oxygen) Sensor saves the day Ignoring all the subtleties, a good combustion will produce an Oxygen level at the exhaust that is equal to that of the surrounding air - Lambda sensors measure the difference in Oxygen concentrations between the outside air and that in the exhaust. If the mixture is too lean (not enough fuel) the fuel is all burnt before the available Oxygen is consumed - and if the mixture is too rich (too much fuel) then all the Oxygen is consumed leaving unburnt fuel. The Lambda’s used on the M60/M62/M62TUB engines are narrow band and inform the engine if the Oxygen level is too low - or too high which relates to a mixture that is too rich or too lean respectively. But, these short-term deviations are not important, the ECU filters the Lambda output to determine if the mean value is correct. (INPA will show you the live output from the Lambda sensors, you will see the output swinging around - you will also see the integrated output which shows the filtered value). So, let’s add the Lambda to the engine below, at the moment everything is Hunky Dory:
That’s spot-on mate!
input 1 gram of air per rev output 10ms injector duration
There we go, we didn’t need that Lambda sensor after all - well until things wear and leak - let’s start with the most obvious problem and the most common - air leaks
MAF
THROTTLE BODY
FUEL INJECTO R
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
That’s miles too lean - add more fuel next time mate!
input 0.5 grams of air per rev output 5ms injector duration
We’ve added an air-leak, if the leak was after the throttle body we would call it a vacuum leak. The Lambda system has noticed that the Oxygen level is too high and that indicates the mixture is too weak. This is where Adaptations come into play. To compensate for the un- metered air the ECU is going to increase the injector time (dwell) to richen the mixture. This compensation is not immediate, instead, over thousands of engine revolutions the injector duration is slowly increased. These compensations are called ADAPTATIONS and are stored in the ECU so that when the engine is re-started the information is available to be used. Note: The M60 engine adaptations only remained when battery power was available - disconnecting the battery would clear all adaptations (called a Magic Reset) - the M62 ECU stored Adaptations in Flash Memory and could not be simply erased.
Air leak at manifold, PCV, gaskets, boots etc
ECU THINKS:  Iíll remember that, if the input conditions are the same Iíll add a tiny bit more fuel next time   If the mixture is still too lean the time after that Iíll add a little more - Iíll keep doing that until the mixture is correct and store the amount in: ADAPTATIONS Int filter/integrator Int filter/integrator
Lambda-Probe Voltage - This is the raw output from the Lambda probe - in this case we are looking at Bank 1 which is right hand bank (when viewed from behind the car). Lambda probes do nothing at all until they have reached operating temperature and this value will stay stationary for a couple of minutes - it then should start moving around the scale. Due to the refresh rate of the screen you will not see it move smoothly, nor will you see that it is actually a sinusoidal waveform - instead it will just seem to flap around a bit. When the engine is at operating temperature the Lambda sensor is informing the ECU of the remaining Oxygen level in the exhaust - and that, in turn, indicates the initial air/fuel mixture. The M60/M62/M62TUB engines employ narrow band Lambda sensors which mean they can only indicate a mixture is too weak or too lean. The ECU continually makes small adjustments to the injector dwell in response to the raw Lambda output - for example, the Lambda will report that the mixture is too weak and the ECU will increase injector dwell (the time it is open) - it does this in tiny increments - until the Lambda signal ‘flops’ high indicating that the mixture is too rich. This behaviour is normal operation for all models with narrow-band Lambda sensors. Later models with the N62 engine variants have wide band Lambda sensors and they behave completely differently reporting absolute Oxygen levels and don’t flop about. On both types, a zero value indicates that the sensor has failed short-circuit and the ECU will store an error message. In this situation the ECU ignores the Lambda value and instead uses other sensors (such as the throttle position sensor and MAF readings) to estimate the correct air/fuel mixture. Lambda sensor rarely fail, but are replaced in their thousands because diagnostics will show a Lambda error of some sort - which is akin to replacing temperature sensors if the engine is running hot. Later models could report ‘Lambda Ageing’ error codes which was an indication that they were responding slowly to Oxygen levels - and that was usually because they were covered in soot. Monitor Probe 1 After KAT - some models have additional Lambda sensors AFTER the catalytic converters. These monitor the performance of the catalytic element which should be storing Oxygen when it is plentiful, and releasing it when the Oxygen levels drop below that of atmospheric levels. What you expect to see at this point is a slight change in Oxygen levels which will follow the pre-cat sensor (but delayed by the Oxygen-holding capacity of the catalytic element) - but at a much lower amplitude. If the catalytic converter has failed this sensor will follow the pre-cat sensors at the same amplitude - the ECU would then decide the catalytic element had failed and bung up an error code. Models such as the E31 don’t have these fitted and the value stays stationary at around 0.8V. The values reported do not affect the air/fuel ration - although a blocked cat does! Lambda Intergrator - This is the filtered and integrated output from the pre-cat Lambda sensor. The raw sinusoidal output from the sensor is low-pass filtered and then referenced to a value of 0. What all that blurb means is that if the fuel/air mixture is correct then we would expect to see a value of around 0.00 here. A higher value indicates a LEAN mixture, a lower value indicates a RICH mixture - it’s as simple as that! This flops all over the place as the Lambda sensors reach operating temperature so ignore that bit, once the engine has reached operating temperature this will change value by small amounts but centre around 0.00 If the adaptations were deleted we would expect this value to deviate from 0.00 (unless the engine was absolutely perfect) - and we would expect to see the adaptations slowly changing in value until we get to a point where the adaptations have managed to get this value back to 0.00. If this does not happen then the ECU will report ‘adaptations at limits’ and bung on the check engine warning lamp. Adaption Value Additive - If the Lambda Integrator reports that the mixture is too lean (at idle) then the ECU will slowly increase this value to increase the injector dwell so that the mixture enriches. If you have a value here that it greater than +10 you can be sure you have a vacuum leak - or the MAF is mis-reporting the actual air mass. If the value here moves to less than -10 (especially if combined with a negative value for the multiplicative adaptations) that usually points to a failure of the vacuum pipe that runs between the PCV and the Fuel Pressure Regulator (FPR) - at idle the PCV will be supplying a vacuum to the FPR which limits the fuel-rail pressure to 3.0 Bar - if that vacuum is missing (the pipe is kinked, torn or missing) then the fuel-rail pressure will increase to 3.5 Bar and adaptations will be seriously skewed trying to pull the fuel/air mixture back to the correct levels. A slightly negative reading indicates less than perfect combustion (plugs, coils) Adaption Value Multiplicative - This value is modified if the mixture is not ideal at higher engine loads and speeds (when cruising for instance). If this one moves to far away from 1.00 then things are not right - a vacuum leak is much less likely as the manifold vacuum reduces with engine load and that proportionally reduces its influence. However, a large additive and small multiplicative positive increase does point towards an air or vacuum leak. A large negative number here could be excessive fuel-rail pressure - but it could also be poor combustion in one or more cylinders - the smoothness values would help us differentiate the two possibilities
SMOOTHNESS (also know as roughness on some models)
Practical measurements using INPA diagnostics The three important screens that will find most running problems ANALOG VALUES 2 Lambda Sensors and Adaptation values Right, we know what Adaptations are now - they are values learnt by the ECU to compensate for imperfections, and that includes imperfections with the sensors as well as mechanical problems such as air and vacuum leaks. Let’s have a look at an INPA screenshot  (Analog value 2) from an M62TUB44 after it has reached operating temperature (I’ve annotated Bank 1):
RAW output from the Lambda sensor BEFORE the catalytic converter. This is a measurement of the remaining Oxygen in the exhaust gasses and indicates the fuel/air mixture before combustion This (should) constantly change in voltage (0.2V - 0.9V)
Raw output of Lambda AFTER the catalytic converter - this effectively measures catalytic converter condition. We will ignore this value as it has no bearing on adaptations
Integrated Lambda signal, it is an indication of fuel/air mixture with less flopping about - if the mixture is correct this will settle at around 0. A positive value indicates a LEAN mixture. With a stable mixture this value should move around a zero value
Additive Adaptation - How much injector dwell is ADDED or SUBTRACTED So, (say) 10ms + 1ms injector dwell. This is example is close enough at 0.07
Multiplicative Adaptation - How much the injector dwell is MULTIPLIED by So, (say) 10ms injector dwell x 2 = 20ms This is example is close enough at 1.03
The SMOOTHNESS VALUE is an indication of the consistency of providing crankshaft acceleration at idle for each cylinder. If that effort was the same every camshaft revolution then the value would stay at ZERO (a completely dead cylinder will give a zero reading) As cylinder combustion is never perfect you will get differing levels of effort being made for the same cylinder - the greater that difference the higher the smoothness value (a dodgy cylinder will give a higher reading) This example is of a healthy engine, lower values can be seen, especially if you restart diagnostics when the engine is running (usually the source of ‘my engine is very smooth’ screenshots online!)
The screenshot above is from my 840ci, and so is the one on the left, but before I fixed all sorts of vacuum leaks. The smoothness and Lambda screens showed that things were not happy - my first plan was to swap coils around (as it is easy to do) to see if cylinder 5 would perk up a bit - but it didn’t, so I could discount ignition problems It was the combination of Smoothness and Adaptations that pointed towards a vacuum leak - using the Smoothness values ruled out a dodgy ignition coil
Click for repair information Click for repair information
MAF
THROTTLE BODY
FUEL INJECTO R
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
That’s spot-on mate!
input 0.5 grams of air per rev output 5ms injector duration PLUS ADDITIVE ADAPTATION of 5ms
That’s basic adaptation at work - although the MAF measured only 0.5 grams of air per revolution the ADAPTATIONS have requested an additional 5ms injector duration. It took quite a while for adaptations to work themselves up to this point (if a large air-leak is introduced it may take ten minutes at idle for adaptations to pull the mixture back correctly). But, now the fuel/air mixture is correct (but only at this engine speed and load) and all is jolly. The EVIDENCE that something is wrong is that the Additive adaptations will be quite noticeable - if the air-leak was large enough (like this example is) then you will get an engine warning lamp lit and INPA will show ‘adaptations at limit’. However, as long as the ECU has done its job correctly there should be no misfire, the engine will be as smooth as normal as the mixture is now correct again. Additive and Multiplicative Adaptations I’ve seen a couple of documents regarding when these two adaptation types are modified - the blurb says: Additive adaptations are made at IDLE, LOW LOAD and LOW TO MID RANGE ENGINE SPEEDS Multiplicative adaptations are made at NORMAL TO HIGHER LOADS when at HIGHER ENGINE SPEEDS But, my experience of the M62B44 shows that the Multiplicative adaptations can be modified at idle when the Additive adaptations reach their limits, so I’m not sure if the above information is perfectly true! But, it is probably close enough for our purposes. As far as their effects on engine performance is concerned, we can broadly say that: The Additive adaptations have more effect at idle and only slightly modify the cruising and acceleration performance. The Multiplicative adaptations affect every aspect of engine performance and that includes idle
Air leak at manifold, PCV, gaskets, boots etc
Int filter/integrator
This is the correct temperature when the M62 is fitted to an E31 - The E38 has a mapped thermostat and at idle the temperature should be 105C - 108C
The ECU has calculated that the ICV (Idle-speed Control Valve) needs to open sufficiently to pass 24Kg/h - this value causes much angst as it often has the (!) warning - but this value is within limits
NOTE:  Although we have an air leak, the Integrated Lambda signal at this point is back to a value of 1 - thatís because adaptations have got the mixture correct again - so you canít use the Integrated Lambda signal for fault-finding UNLESS adaptations have reached limits
Total air consumption On the V8’s it should be around 20Kg/h as seen here. When the engine is cold it is normal to get a warning (!) - the slider scale was designed for lesser engines!
This engine speed is normal if A/C is ON - if A/C is OFF it should be around 550-600 RPM
Don’t bother diagnosing problems if the running voltage is less than 12.6V
The screen above is always a good place to start when things aren’t running nicely - it gives a good indication of the basic sensors: Battery Voltage - with the engine running we expect a voltage between 12.6V to 14.6V. Anything below 12.6V means that something is wrong with the alternator and low voltages will cause ignition problems - so get that bit fixed first! Engine Speed - On the M60, M62 and M62TUB the engine revs should be 550 - 600 with the A/C OFF. If the A/C is switched ON and working then the revs should increase to 700. Air Intake Temperature - On the M60 engine this temperature sensor is stuck on the RHS of the intake manifold, on the M62 engine it is incorporated into the MAF - although on some models there is an additional sensor on the air filter housing. The reported temperature should be around the ambient temperature plus a few degrees. If the temperature is mis-reported this will cause the adaptations to move away from the ideal. Replace the MAF if the error is more than five or six degrees out. However, on the N62 engines this value is often much higher even on new MAF’s. Coolant Temperature - This is the coolant temperature of the ENGINE. On some models the radiator outlet temperature is also reported - we are not interested in that when finding engine running problems. The engine must be at running temperature for basic diagnostics. Although the M62 engine is used across a few models, the coolant temperature is lower when used in the E31 as this has a fixed 85C thermostat - whereas the E38 and E39 have a temperature-mapped thermostat with a passive opening temperature of 104C - at idle the reported temperature would be around this value. When performing diagnostics (unless you are looking for cold-start problems) it is imperative that the engine reaches operating temperature - and if the engine fails to reach the thermostat opening temperature then that could well be the source of the engine performance problems Needed Air I.S. Controller - On the M60 and M62 (not the TUB version) the idle speed is controlled by an Idle-speed Control Valve (ICV). The ECU calculates how much air this has to allow through it to maintain the correct idle speed. This is the Needed air i.s. controller value. Unfortunately the scale (just like that of the Total Air Consumption slider) is too short for the mighty V8’s and although everything is working perfectly you often (nearly always) get the (!) warning next to it. Don’t panic, this is perfectly normal for the V8’s Total Air Consumption HLM - This is the airflow that the MAF is reporting. This often causes angst because a warning (!) is shown. But, as long as this value is around 20Kg/h - 25Kg/h then everything is fine for the V8’s. Just like the previous slider, the scale seems to have been made too short for the larger engines. If diagnosing the car from cold this value will be much higher and the warning (!) will be shown, again, this is perfectly normal. The lack of a value here means that the MAF is not connected or has failed. If the value is less than 18Kg/h when the engine is hot that will indicate a vacuum leak, possibly around the inlet manifold. Readings that are absolutely miles out usually indicate a failed MAF Throttle Potentiometer - this is the voltage reported from the throttle position sensor which is fitted to the throttle body on the M60 and M62. The M62TUB has a motorised throttle body (as does the N62) but this value has been retained and is interpreted from the EML system rather than directly from the throttle body. A voltage around 0.45V is expected - plus or minus 0.1V. As the throttle is pressed this value will increase. Due to the refresh rate of the diagnostic screen the value will move in a jerky fashion - unless the value jumps backwards as the throttle is increased then the potentiometer is probably OK.
On the M60 and M62 this value is reported from the throttle body potentiometer. This value will move if the throttle is opened - around 0.45V is expected at idle
ANALOG VALUES 1 Primary and secondary engine sensors
OPEN - LOOP MIXTURE CONTROL
CLOSED - LOOP MIXTURE CONTROL
AIR LEAK INTRODUCED
ADAPTATIONS COMPENSATE
HOW ENGINE PROBLEMS AFFECT THE READINGS So, we know a lot more about how to use diagnostics and what each of the screens can show us if we have an engine running problem. Obviously, if you have a part of the engine that has completely died (such as a coil-pack) then error codes are stored, and then repair is straightforward - and you probably won’t be reading this. But, when parts sort of work but not properly then these three screens will help us whittle the possibilities down. Let’s have a quick look at problems and how they affect the readings. Oil in the sparkplug wells (details and repair information here) This problem causes misfires on single cylinders rather than an overall lumpiness of all 8 cylinders. If the coil completely failed we would find a stored error code, and the ECU would inhibit the injector on that cylinder to stop unburnt fuel getting to the catalytic converters. But where it fires feebly and intermittently we can find evidence on both Adaptations and Smoothness. We would expect to see an increase in the smoothness value for that cylinder AND the Additive Adaptations would be below zero as they compensated for the partially combusted fuel Failing catalytic converter (details and repair information here) Catalytic converters can fail in a way that blocks the flow of exhaust gasses - either by melting or disintegrating. When they disintegrate parts of the honeycomb can become detached and block the outlet from the converter casing. In this situation the error happens quite quickly, the car starts shaking and power is lost - but when the car is stopped the errant bit of honeycomb of falls away from the outlet and all is good when re-started. Where the honeycomb melts the exhaust flow is reduced and so is engine power - but the evidence it leaves is quite noticeable. This is one of the few errors that shows adaptations completely different between the two Banks - one will be positive, the other negative. The reason for this is that we only have one MAF - and two banks. If the flow of gasses is inhibited on one bank then that bank becomes richer, and the other leaner. It is also possible to get knock sensor error codes when things get badly blocked. Vacuum leaks around the manifold gaskets (details and repair information here) Manifold leaks can affect the smoothness of single cylinders and adjacent cylinders along with an increase of Additive Adaptations. This is due to the construction of the gaskets which serve two adjacent cylinders and the design of the one-piece inlet manifold. The difference between faulty coil packs and manifold leaks is that the latter increases Additive Adaptations whereas a faulty coil pack (well, until it gives up completely) reduces the adaptations. Fuel pressure regulation problems (details mentioned in this article) The TIS always mentions fuel-rail pressure as the first thing that is checked if you have engine running problems. But, as a general rule they are pretty well behaved. But they do two things that really upset the engine. They can leak internally and that pushes raw fuel directly into the manifold via the vacuum pipe that runs between the FPR and the PCV. That makes starting the engine difficult as the manifold is flooded - but as far as diagnostics go it pushes the Additive Adaptations negative and affects the Multiplicative Adaptations in a much lesser way. If the pipe is removed it will be found to be wet with fuel. The pipe between the FPR and the PCV can be punctured and this has the effect of increasing fuel-rail pressure to 3.5 Bar (instead of 3 Bar) and that will increase the amount of fuel that is added in all engine ranges except full throttle. In this situation Additive Adaptations will be very negative and Multiplicative Adaptations will be negative to a lesser extent. A quick check for this problem is to pinch the vacuum pipe and remove the FPR end - if the engine note does NOT change the pipe is blocked, puncture or the FPR is faulty. Vacuum leaks on external manifold parts (details and repair information here) These leaks can be around the throttle body, around the PCV gasket, the vacuum lines to the brake booster and then capped off service ports as mentioned in the article above. These leaks are easily compensated for by adaptations and the clue is that Additive Adaptations are positive, and Multiplicative Adaptations are positive to a much lesser extent. Quite often the engine is perfectly happy until the adaptations reach their limits. MAF problems (discussed here) The MAF always gets the blame - and the usual advice is to disconnect it and see if the engine runs better - and it quite often does. With the MAF disconnected the other sensors take the primary role - the throttle potentiometer being the primary airflow sensor. But, if you want to do this test correctly - switch off the car, ignition back ON, use diagnostics to clear the engine adaptations, disconnect the MAF, switch the ignition OFF and then re-start the car - how’s it running now? Using this method will show if the default engine values give good performance, and if they do the MAF is suspect. If the engine runs badly then the fault is elsewhere. Faulty MAF’s can cause all sorts of problems - but the signature of a failed MAF is very high adaptations, quite often with Additive Adaptations being negative and Multiplicative Adaptations being positive. There is often a lack of performance, especially under harsh acceleration where the Lambda sensor has no effect at all. PCV failure (details and repair information here) Not all PCV failures cause smoke, some just let lots of un-metered air in (they usually make a whistling noise at the same time). Sometimes they just let a small amount of air in and these leaks are easily compensated for by adaptations and the clue is that Additive Adaptations are positive, and Multiplicative Adaptations are positive to a much lesser extent. Quite often the engine is perfectly happy until the adaptations reach their limits. However, they usually get worse to a point where you get several misfires, especially on a cold start.
Please keep meeknet online! Please keep meeknet online! timms BMW repairs and information
That’s obviously not right at all! I trawled this from the internet as an example. I would expect that the Adaptations were at limits on this example as cylinder 5 is hardly firing consistently. Where a cylinder fires inconsistently there will be unburnt fuel getting to the Lambda sensor - the ECU will try and lean-out the mixture but that will start to affect the other cylinders This example is quite interesting as Bank 2 (cylinders 5 - 8) is badly affected whereas Bank 1 (cylinders 1 - 4) look pretty happy - although the value of zero on cylinder 2 probably means it’s not doing anything at all. I would try and get cylinder 2 firing again - but my best guess is that the catalytic converter is blocked on Bank 2
SEARCH MEEKNET
SEARCH MEEKNET
Oil Leaks around the Valve Covers Silencing Noisy Tappets Solving TRANS FAIL-SAFE PROG Problems Solving Boot (Trunk) Hinge Wiring Problems Curing ASC/ABS Problems
MAF
THROTTLE BODY
FUEL INJECTOR
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
MAF
THROTTL E BODY
FUEL INJECTOR
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
Timm's BMW Engines - Diagnostics and Adaptations What are they all about and how to fix engine running problems This is a big subject - engine running problems and adaptations - especially ‘adaptations at limits’ which light up the engine warning lamp. There is loads of advice on the Forums that say ‘you need diagnostics’ - but what do you actually do with diagnostics - and what do all those values mean? This document is for those that have engine running problems and want to fix them with the help of diagnostics - in this case we are using INPA. To get us going we are going to have to understand adaptations first! ADAPTATIONS Looking at the stored adaptation values gives us a good insight into the condition of the engine and the source of the problems you may be having - so we are going to have to understand them first. And to do that we are going to look at a single cylinder of our engines and ignore all the other sensors. All we are interested in is the basic fuel/air mixture which is provided by measuring air MASS (with a MAF sensor) - the ECU (engine computer) then computes how long to open the injector for:
input 1 gram of air per rev output 10ms injector duration
So, above is the very basic plan - measure the air input and decide on how long to open the injector - this happens every camshaft revolution. The target is to get the fuel/air ratio correct because this provides efficient combustion and clean exhaust gasses. But, it is pretty obvious that there are going to be errors, and early engines had an adjustment for the air measuring device (which was an AIRFLOW METER rather than a MAF) so that you could compensate for wear, air leaks, blocked injectors and a myriad of other possibilities. So - engine manufacturers added a way of checking the fuel/air mixture by using a Lambda (Oxygen) sensor. The Lambda (Oxygen) Sensor saves the day Ignoring all the subtleties, a good combustion will produce an Oxygen level at the exhaust that is equal to that of the surrounding air - Lambda sensors measure the difference in Oxygen concentrations between the outside air and that in the exhaust. If the mixture is too lean (not enough fuel) the fuel is all burnt before the available Oxygen is consumed - and if the mixture is too rich (too much fuel) then all the Oxygen is consumed leaving unburnt fuel. The Lambda’s used on the M60/M62/M62TUB engines are narrow band  and inform the engine if the Oxygen level is too low - or too high which relates to a mixture that is too rich or too lean respectively. But, these short-term deviations are not important, the ECU filters the Lambda output to determine if the mean value is correct. (INPA will show you the live output from the Lambda sensors, you will see the output swinging around - you will also see the integrated output which shows the filtered value). So, let’s add the Lambda to the engine below, at the moment everything is Hunky Dory:
That’s spot-on mate!
input 1 gram of air per rev output 10ms injector duration
There we go, we didn’t need that Lambda sensor after all - well until things wear and leak - let’s start with the most obvious problem and the most common - air leaks
MAF
THROTTL E BODY
FUEL INJECTOR
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
That’s miles too lean - add more fuel next time mate!
input 0.5 grams of air per rev output 5ms injector duration
We’ve added an air-leak, if the leak was after the throttle body we would call it a vacuum leak. The Lambda system has noticed that the Oxygen level is too high and that indicates the mixture is too weak. This is where Adaptations come into play. To compensate for the un-metered air the ECU is going to increase the injector time (dwell) to richen the mixture. This compensation is not immediate, instead, over thousands of engine revolutions the injector duration is slowly increased. These compensations are called ADAPTATIONS and are stored in the ECU so that when the engine is re-started the information is available to be used. Note: The M60 engine adaptations only remained when battery power was available - disconnecting the battery would clear all adaptations (called a Magic Reset) - the M62 ECU stored Adaptations in Flash Memory and could not be simply erased.
Air leak at manifold, PCV, gaskets, boots etc
ECU THINKS:  Iíll remember that, if the input conditions are the same Iíll add a tiny bit more fuel next time   If the mixture is still too lean the time after that Iíll add a little more - Iíll keep doing that until the mixture is correct and store the amount in: ADAPTATIONS Int filter/integrator Int filter/integrator
Lambda-Probe Voltage - This is the raw output from the Lambda probe - in this case we are looking at Bank 1 which is right hand bank (when viewed from behind the car). Lambda probes do nothing at all until they have reached operating temperature and this value will stay stationary for a couple of minutes - it then should start moving around the scale. Due to the refresh rate of the screen you will not see it move smoothly, nor will you see that it is actually a sinusoidal waveform - instead it will just seem to flap around a bit. When the engine is at operating temperature the Lambda sensor is informing the ECU of the remaining Oxygen level in the exhaust - and that, in turn, indicates the initial air/fuel mixture. The M60/M62/M62TUB engines employ narrow band Lambda sensors which mean they can only indicate a mixture is too weak or too lean. The ECU continually makes small adjustments to the injector dwell in response to the raw Lambda output - for example, the Lambda will report that the mixture is too weak and the ECU will increase injector dwell (the time it is open) - it does this in tiny increments - until the Lambda signal ‘flops’ high indicating that the mixture is too rich. This behaviour is normal operation for all models with narrow-band Lambda sensors. Later models with the N62 engine variants have wide band Lambda sensors and they behave completely differently reporting absolute Oxygen levels and don’t flop about. On both types, a zero value indicates that the sensor has failed short- circuit and the ECU will store an error message. In this situation the ECU ignores the Lambda value and instead uses other sensors (such as the throttle position sensor and MAF readings) to estimate the correct air/fuel mixture. Lambda sensor rarely fail, but are replaced in their thousands because diagnostics will show a Lambda error of some sort - which is akin to replacing temperature sensors if the engine is running hot. Later models could report ‘Lambda Ageing’ error codes which was an indication that they were responding slowly to Oxygen levels - and that was usually because they were covered in soot. Monitor Probe 1 After KAT - some models have additional Lambda sensors AFTER the catalytic converters. These monitor the performance of the catalytic element which should be storing Oxygen when it is plentiful, and releasing it when the Oxygen levels drop below that of atmospheric levels. What you expect to see at this point is a slight change in Oxygen levels which will follow the pre-cat sensor (but delayed by the Oxygen-holding capacity of the catalytic element) - but at a much lower amplitude. If the catalytic converter has failed this sensor will follow the pre-cat sensors at the same amplitude - the ECU would then decide the catalytic element had failed and bung up an error code. Models such as the E31 don’t have these fitted and the value stays stationary at around 0.8V. The values reported do not affect the air/fuel ration - although a blocked cat does! Lambda Intergrator - This is the filtered and integrated output from the pre-cat Lambda sensor. The raw sinusoidal output from the sensor is low-pass filtered and then referenced to a value of 0. What all that blurb means is that if the fuel/air mixture is correct then we would expect to see a value of around 0.00 here. A higher value indicates a LEAN mixture, a lower value indicates a RICH mixture - it’s as simple as that! This flops all over the place as the Lambda sensors reach operating temperature so ignore that bit, once the engine has reached operating temperature this will change value by small amounts but centre around 0.00 If the adaptations were deleted we would expect this value to deviate from 0.00 (unless the engine was absolutely perfect) - and we would expect to see the adaptations slowly changing in value until we get to a point where the adaptations have managed to get this value back to 0.00. If this does not happen then the ECU will report ‘adaptations at limits’ and bung on the check engine warning lamp. Adaption Value Additive - If the Lambda Integrator reports that the mixture is too lean (at idle) then the ECU will slowly increase this value to increase the injector dwell so that the mixture enriches. If you have a value here that it greater than +10 you can be sure you have a vacuum leak - or the MAF is mis- reporting the actual air mass. If the value here moves to less than -10 (especially if combined with a negative value for the multiplicative adaptations) that usually points to a failure of the vacuum pipe that runs between the PCV and the Fuel Pressure Regulator (FPR) - at idle the PCV will be supplying a vacuum to the FPR which limits the fuel-rail pressure to 3.0 Bar - if that vacuum is missing (the pipe is kinked, torn or missing) then the fuel-rail pressure will increase to 3.5 Bar and adaptations will be seriously skewed trying to pull the fuel/air mixture back to the correct levels. A slightly negative reading indicates less than perfect combustion (plugs, coils) Adaption Value Multiplicative - This value is modified if the mixture is not ideal at higher engine loads and speeds (when cruising for instance). If this one moves to far away from 1.00 then things are not right - a vacuum leak is much less likely as the manifold vacuum reduces with engine load and that proportionally reduces its influence. However, a large additive and small multiplicative positive increase does point towards an air or vacuum leak. A large negative number here could be excessive fuel-rail pressure - but it could also be poor combustion in one or more cylinders - the smoothness values would help us differentiate the two possibilities
Practical measurements using INPA diagnostics The three important screens that will find most running problems ANALOG VALUES 2 Lambda Sensors and Adaptation values Right, we know what Adaptations are now - they are values learnt by the ECU to compensate for imperfections, and that includes imperfections with the sensors as well as mechanical problems such as air and vacuum leaks. Let’s have a look at an INPA screenshot (Analog value 2) from an M62TUB44 after it has reached operating temperature (I’ve annotated Bank 1):
RAW output from the Lambda sensor BEFORE the catalytic converter. This is a measurement of the remaining Oxygen in the exhaust gasses and indicates the fuel/air mixture before combustion This (should) constantly change in voltage (0.2V - 0.9V)
Raw output of Lambda AFTER the catalytic converter - this effectively measures catalytic converter condition. We will ignore this value as it has no bearing on adaptations
Integrated Lambda signal, it is an indication of fuel/air mixture with less flopping about - if the mixture is correct this will settle at around 0. A positive value indicates a lean mixture. With a stable mixture this value should move around a zero value
Additive Adaptation - How much injector dwell is ADDED or SUBTRACTED So, (say) 10ms + 1ms injector dwell. This is example is close enough at 0.07
Multiplicative Adaptation - How much the injector dwell is MULTIPLIED by So, (say) 10ms injector dwell x 2 = 20ms This is example is close enough at 1.03
SMOOTHNESS (also know as roughness on some models)
The SMOOTHNESS VALUE is an indication of the consistency of providing crankshaft acceleration at idle for each cylinder. If that effort was the same every camshaft revolution then the value would stay at ZERO (a completely dead cylinder will give a zero reading) As cylinder combustion is never perfect you will get differing levels of effort being made for the same cylinder - the greater that difference the higher the smoothness value (a dodgy cylinder will give a higher reading) This example is of a healthy engine, lower values can be seen, especially if you restart diagnostics when the engine is running (usually the source of ‘my engine is very smooth’ screenshots online!)
The screenshot above is from my 840ci, and so is the one on the left, but before I fixed all sorts of vacuum leaks. The smoothness and Lambda screens showed that things were not happy - my first plan was to swap coils around (as it is easy to do) to see if cylinder 5 would perk up a bit - but it didn’t, so I could discount ignition problems It was the combination of Smoothness and Adaptations that pointed towards a vacuum leak - using the Smoothness values ruled out a dodgy ignition coil
Click for repair information Click for repair information
That’s obviously not right at all! I trawled this from the internet as an example. I would expect that the Adaptations were at limits on this example as cylinder 5 is hardly firing consistently. Where a cylinder fires inconsistently there will be unburnt fuel getting to the Lambda sensor - the ECU will try and lean-out the mixture but that will start to affect the other cylinders This example is quite interesting as Bank 2 (cylinders 5 - 8) is badly affected whereas Bank 1 (cylinders 1 - 4) look pretty happy - although the value of zero on cylinder 2 probably means it’s not doing anything at all. I would try and get cylinder 2 firing again - but my best guess is that the catalytic converter is blocked on Bank 2
MAF
THROTTL E BODY
FUEL INJECTOR
LAMBDA SENSOR
ECU (Engine computer)
To catalytic converters and exhaust system
Fresh air from air filter
That’s spot-on mate!
input 0.5 grams of air per rev output 5ms injector duration PLUS ADDITIVE ADAPTATION of 5ms
That’s basic adaptation at work - although the MAF measured only 0.5 grams of air per revolution the ADAPTATIONS have requested an additional 5ms injector duration. It took quite a while for adaptations to work themselves up to this point (if a large air-leak is introduced it may take ten minutes at idle for adaptations to pull the mixture back correctly). But, now the fuel/air mixture is correct (but only at this engine speed and load) and all is jolly. The EVIDENCE that something is wrong is that the Additive adaptations will be quite noticeable - if the air-leak was large enough (like this example is) then you will get an engine warning lamp lit and INPA will show ‘adaptations at limit’. However, as long as the ECU has done its job correctly there should be no misfire, the engine will be as smooth as normal as the mixture is now correct again. Additive and Multiplicative Adaptations I’ve seen a couple of documents regarding when these two adaptation types are modified - the blurb says: Additive adaptations are made at IDLE, LOW LOAD and LOW TO MID RANGE ENGINE SPEEDS Multiplicative adaptations are made at NORMAL TO HIGHER LOADS when at HIGHER ENGINE SPEEDS But, my experience of the M62B44 shows that the Multiplicative adaptations can be modified at idle when the Additive adaptations reach their limits, so I’m not sure if the above information is perfectly true! But, it is probably close enough for our purposes. As far as their effects on engine performance is concerned, we can broadly say that: The Additive adaptations have more effect at idle and only slightly modify the cruising and acceleration performance. The Multiplicative adaptations affect every aspect of engine performance and that includes idle
Air leak at manifold, PCV, gaskets, boots etc
Int filter/integrator
This is the correct temperature when the M62 is fitted to an E31 - The E38 has a mapped thermostat and at idle the temperature should be 105C - 108C
The ECU has calculated that the ICV (Idle- speed Control Valve) needs to open sufficiently to pass 24Kg/h - this value causes much angst as it often has the (!) warning - but this value is within limits
NOTE:  Although we have an air leak, the Integrated Lambda signal at this point is back to a value of 1 - thatís because adaptations have got the mixture correct again - so you canít use the Integrated Lambda signal for fault-finding UNLESS adaptations have reached limits
Total air consumption On the V8’s it should be around 20Kg/h as seen here. When the engine is cold it is normal to get a warning (!) - the slider scale was designed for lesser engines!
This engine speed is normal if A/C is ON - if A/C is OFF it should be around 550-600 RPM
Don’t bother diagnosing problems if the running voltage is less than 12.6V
The screen above is always a good place to start when things aren’t running nicely - it gives a good indication of the basic sensors: Battery Voltage - with the engine running we expect a voltage between 12.6V to 14.6V. Anything below 12.6V means that something is wrong with the alternator and low voltages will cause ignition problems - so get that bit fixed first! Engine Speed - On the M60, M62 and M62TUB the engine revs should be 550 - 600 with the A/C OFF. If the A/C is switched ON and working then the revs should increase to 700. Air Intake Temperature - On the M60 engine this temperature sensor is stuck on the RHS of the intake manifold, on the M62 engine it is incorporated into the MAF - although on some models there is an additional sensor on the air filter housing. The reported temperature should be around the ambient temperature plus a few degrees. If the temperature is mis-reported this will cause the adaptations to move away from the ideal. Replace the MAF if the error is more than five or six degrees out. However, on the N62 engines this value is often much higher even on new MAF’s. Coolant Temperature - This is the coolant temperature of the ENGINE. On some models the radiator outlet temperature is also reported - we are not interested in that when finding engine running problems. The engine must be at running temperature for basic diagnostics. Although the M62 engine is used across a few models, the coolant temperature is lower when used in the E31 as this has a fixed 85C thermostat - whereas the E38 and E39 have a temperature-mapped thermostat with a passive opening temperature of 104C - at idle the reported temperature would be around this value. When performing diagnostics (unless you are looking for cold-start problems) it is imperative that the engine reaches operating temperature - and if the engine fails to reach the thermostat opening temperature then that could well be the source of the engine performance problems Needed Air I.S. Controller - On the M60 and M62 (not the TUB version) the idle speed is controlled by an Idle-speed Control Valve (ICV). The ECU calculates how much air this has to allow through it to maintain the correct idle speed. This is the Needed air i.s. controller value. Unfortunately the scale (just like that of the Total Air Consumption slider) is too short for the mighty V8’s and although everything is working perfectly you often (nearly always) get the (!) warning next to it. Don’t panic, this is perfectly normal for the V8’s Total Air Consumption HLM - This is the airflow that the MAF is reporting. This often causes angst because a warning (!) is shown. But, as long as this value is around 20Kg/h - 25Kg/h then everything is fine for the V8’s. Just like the previous slider, the scale seems to have been made too short for the larger engines. If diagnosing the car from cold this value will be much higher and the warning (!) will be shown, again, this is perfectly normal. The lack of a value here means that the MAF is not connected or has failed. If the value is less than 18Kg/h when the engine is hot that will indicate a vacuum leak, possibly around the inlet manifold. Readings that are absolutely miles out usually indicate a failed MAF Throttle Potentiometer - this is the voltage reported from the throttle position sensor which is fitted to the throttle body on the M60 and M62. The M62TUB has a motorised throttle body (as does the N62) but this value has been retained and is interpreted from the EML system rather than directly from the throttle body. A voltage around 0.45V is expected - plus or minus 0.1V. As the throttle is pressed this value will increase. Due to the refresh rate of the diagnostic screen the value will move in a jerky fashion - unless the value jumps backwards as the throttle is increased then the potentiometer is probably OK.
On the M60 and M62 this value is reported from the throttle body potentiometer. This value will move if the throttle is opened - around 0.45V is expected at idle
ANALOG VALUES 1 Primary and secondary engine sensors
OPEN - LOOP MIXTURE CONTROL
CLOSED - LOOP MIXTURE CONTROL
AIR LEAK INTRODUCED
ADAPTATIONS COMPENSATE
HOW ENGINE PROBLEMS AFFECT THE READINGS So, we know a lot more about how to use diagnostics and what each of the screens can show us if we have an engine running problem. Obviously, if you have a part of the engine that has completely died (such as a coil-pack) then error codes are stored, and then repair is straightforward - and you probably won’t be reading this. But, when parts sort of work but not properly then these three screens will help us whittle the possibilities down. Let’s have a quick look at problems and how they affect the readings. Oil in the sparkplug wells (details and repair information here) This problem causes misfires on single cylinders rather than an overall lumpiness of all 8 cylinders. If the coil completely failed we would find a stored error code, and the ECU would inhibit the injector on that cylinder to stop unburnt fuel getting to the catalytic converters. But where it fires feebly and intermittently we can find evidence on both Adaptations and Smoothness. We would expect to see an increase in the smoothness value for that cylinder AND the Additive Adaptations would be below zero as they compensated for the partially combusted fuel Failing catalytic converter (details and repair information here) Catalytic converters can fail in a way that blocks the flow of exhaust gasses - either by melting or disintegrating. When they disintegrate parts of the honeycomb can become detached and block the outlet from the converter casing. In this situation the error happens quite quickly, the car starts shaking and power is lost - but when the car is stopped the errant bit of honeycomb of falls away from the outlet and all is good when re-started. Where the honeycomb melts the exhaust flow is reduced and so is engine power - but the evidence it leaves is quite noticeable. This is one of the few errors that shows adaptations completely different between the two Banks - one will be positive, the other negative. The reason for this is that we only have one MAF - and two banks. If the flow of gasses is inhibited on one bank then that bank becomes richer, and the other leaner. It is also possible to get knock sensor error codes when things get badly blocked. Vacuum leaks around the manifold gaskets (details and repair information here) Manifold leaks can affect the smoothness of single cylinders and adjacent cylinders along with an increase of Additive Adaptations. This is due to the construction of the gaskets which serve two adjacent cylinders and the design of the one-piece inlet manifold. The difference between faulty coil packs and manifold leaks is that the latter increases Additive Adaptations whereas a faulty coil pack (well, until it gives up completely) reduces the adaptations. Fuel pressure regulation problems (details mentioned in this article) The TIS always mentions fuel-rail pressure as the first thing that is checked if you have engine running problems. But, as a general rule they are pretty well behaved. But they do two things that really upset the engine. They can leak internally and that pushes raw fuel directly into the manifold via the vacuum pipe that runs between the FPR and the PCV. That makes starting the engine difficult as the manifold is flooded - but as far as diagnostics go it pushes the Additive Adaptations negative and affects the Multiplicative Adaptations in a much lesser way. If the pipe is removed it will be found to be wet with fuel. The pipe between the FPR and the PCV can be punctured and this has the effect of increasing fuel-rail pressure to 3.5 Bar (instead of 3 Bar) and that will increase the amount of fuel that is added in all engine ranges except full throttle. In this situation Additive Adaptations will be very negative and Multiplicative Adaptations will be negative to a lesser extent. A quick check for this problem is to pinch the vacuum pipe and remove the FPR end - if the engine note does NOT change the pipe is blocked, puncture or the FPR is faulty. Vacuum leaks on external manifold parts (details and repair information here) These leaks can be around the throttle body, around the PCV gasket, the vacuum lines to the brake booster and then capped off service ports as mentioned in the article above. These leaks are easily compensated for by adaptations and the clue is that Additive Adaptations are positive, and Multiplicative Adaptations are positive to a much lesser extent. Quite often the engine is perfectly happy until the adaptations reach their limits. MAF problems (discussed here) The MAF always gets the blame - and the usual advice is to disconnect it and see if the engine runs better - and it quite often does. With the MAF disconnected the other sensors take the primary role - the throttle potentiometer being the primary airflow sensor. But, if you want to do this test correctly - switch off the car, ignition back ON, use diagnostics to clear the engine adaptations, disconnect the MAF, switch the ignition OFF and then re-start the car - how’s it running now? Using this method will show if the default engine values give good performance, and if they do the MAF is suspect. If the engine runs badly then the fault is elsewhere. Faulty MAF’s can cause all sorts of problems - but the signature of a failed MAF is very high adaptations, quite often with Additive Adaptations being negative and Multiplicative Adaptations being positive. There is often a lack of performance, especially under harsh acceleration where the Lambda sensor has no effect at all. PCV failure (details and repair information here) Not all PCV failures cause smoke, some just let lots of un-metered air in (they usually make a whistling noise at the same time). Sometimes they just let a small amount of air in and these leaks are easily compensated for by adaptations and the clue is that Additive Adaptations are positive, and Multiplicative Adaptations are positive to a much lesser extent. Quite often the engine is perfectly happy until the adaptations reach their limits. However, they usually get worse to a point where you get several misfires, especially on a cold start.
Please keep meeknet online!
SEARCH MEEKNET