[RSL]

Originally Posted by NavyBlues

So they've checked and rechecked everything, including a pressure leak test (passed) and checking the wires between the O2 sensors and the ECU, and all check out. They are concluding that the ECU is corrupt. It had been apparently running lean for so long and compensating for it, that it's now forcing the car to run rich, thinking it's lean when it isn't. The lean running was from the leak in the VCG and the pipe at the back end of the turbo, and the inlets, all of which have been repaired.

So I'm looking at about $1400 for a new ECU. : with a prayer that this finally gets me back on the road. What do you guys think?

If adaptations were reset, the DME doesn't remember what it had adjusted to previously. Even if they were not reset, it would be learning back the other direction if the problem was resolved, which doesn't take long, but the car does need to be run for it to happen. AFAIK, there are separate adaptations, one for idle and another for mid/high loads, but not sure of all the conditions needed for the processes to activate.

The rear turbo inlet had nothing to do with a lean condition in one bank. The intake is common, both turbo outlets merge into a single tract before the IC and stay common through the intake manifold into the head. The only way one turbo could directly affect the bank it's on is from the exhaust side. By the same token, it's speed density and based on calculated airflow regardless of how much air is actually coming in and inlet on/off certainly isn't impacting AFR or trims in any large way. Actual airflow difference with inlet on/off is probably barely measurable, or not at all off boost, and would be averaged into the total airflow from both turbos on top of that, making the total impact even smaller. Either way, would not impact one bank and biggest issue would be pulling in unfiltered air.

I've hinted at what I think before and if it were my car, it would've been out of there a while ago. You seem pretty patient and there may always be something else they can think of to try, so long as there's a dollar left in your wallet to pay for it. At some point just have to start thinking it's beyond their ability...or they're just blowing smoke up your a$$. Not saying there can't be odd issues that are extremely difficult to find, but it's going on what, 5-6 weeks now?

Always possible there may be something else in the DME (maybe ignition mosfets instead or something else in it) and maybe a replacement would fix it, but seems they've supposedly fixed, replaced, checked or tested just about any obvious thing it could be at this point and either missed it or still haven't found it. At this point, DME is a $1400 crap shoot...will either fix it or it won't. If you're going to replace the DME either way, I'd find a cheap good used one (not sure if CAS is also needed?) just to test. Still some risk there, but if it fixed it, then consider buying new or making the switch to the relatively problem-free MSD81. If doesn't fix it, at least you're not out nearly as much for still no fix.

At some point, gotta take a step back and think it would be quicker and more cost effective taking it somewhere else that could definitively diagnose the problem without just throwing parts at it on your dime.

[JuniorB]

Have you just tryed to run it and try to pull an engine code. Without any misfires, it should be past the turbo in the exhaust.

[torrque]

@NavyBlues

If you want to try a DME, I can give you the phone number for Guy, he's brilliant. He can re-program a DME to your CAS for under 300. He can also sell you a good working, latest software DME for WAYYY under what you mention there.

he's not an amateur, he does this for a living.

Let me know.

My honest opinion is that it's not the DME, but if you ran out of options, you can try it. I also did, it was not the DME .

[torrque]

Originally Posted by RSL

I wouldn't have thought the TB would've been a factor since it affects the entire motor, but at least it's ruled out. If they can verify the DME, great, but a month seems a bit long to diagnose even the oddest of problems. Can you just swap a DME without the CAS? I don't pay much attention to that stuff.

Still some things that aren't clear:
- is it modded?
- is it tuned and, if so, with what?
- was or is there a DP fix installed somewhere?
- have they traced the O2 sensor wires from the sensors to the DME to verify no breaks/shorts?
- checked all the grounds?
- reset adaptations and given it time to relearn with the new injectors/sensors/fuel?
- were the plugs/coils replaced at any point?
- compression/leak down done?
- did they replace the VC / check PCV system?

you cannot swap the DME without the CAS, they are synched up to each other with an encryption key, engine will never start.

You can take the CAS and DME from another N54 car, and just plug them in, it should work. Just be aware (don't ask me how I know ) that the Kombi instrument will inherit the highest odometer recorded in the CAS.

Ie. if you put in a cas with a lower value, it will not overwrite the current value. If you put in a cas with a higher value, it WILL overwrite it with the higher value...

[NavyBlues]

Originally Posted by RSL

If adaptations were reset, the DME doesn't remember what it had adjusted to previously. Even if they were not reset, it would be learning back the other direction if the problem was resolved, which doesn't take long, but the car does need to be run for it to happen. AFAIK, there are separate adaptations, one for idle and another for mid/high loads, but not sure of all the conditions needed for the processes to activate.

The rear turbo inlet had nothing to do with a lean condition in one bank. The intake is common, both turbo outlets merge into a single tract before the IC and stay common through the intake manifold into the head. The only way one turbo could directly affect the bank it's on is from the exhaust side. By the same token, it's speed density and based on calculated airflow regardless of how much air is actually coming in and inlet on/off certainly isn't impacting AFR or trims in any large way. Actual airflow difference with inlet on/off is probably barely measurable, or not at all off boost, and would be averaged into the total airflow from both turbos on top of that, making the total impact even smaller. Either way, would not impact one bank and biggest issue would be pulling in unfiltered air.

I've hinted at what I think before and if it were my car, it would've been out of there a while ago. You seem pretty patient and there may always be something else they can think of to try, so long as there's a dollar left in your wallet to pay for it. At some point just have to start thinking it's beyond their ability...or they're just blowing smoke up your a$$. Not saying there can't be odd issues that are extremely difficult to find, but it's going on what, 5-6 weeks now?

Always possible there may be something else in the DME (maybe ignition mosfets instead or something else in it) and maybe a replacement would fix it, but seems they've supposedly fixed, replaced, checked or tested just about any obvious thing it could be at this point and either missed it or still haven't found it. At this point, DME is a $1400 crap shoot...will either fix it or it won't. If you're going to replace the DME either way, I'd find a cheap good used one (not sure if CAS is also needed?) just to test. Still some risk there, but if it fixed it, then consider buying new or making the switch to the relatively problem-free MSD81. If doesn't fix it, at least you're not out nearly as much for still no fix.

At some point, gotta take a step back and think it would be quicker and more cost effective taking it somewhere else that could definitively diagnose the problem without just throwing parts at it on your dime.

Originally Posted by RSL

If adaptations were reset, the DME doesn't remember what it had adjusted to previously. Even if they were not reset, it would be learning back the other direction if the problem was resolved, which doesn't take long, but the car does need to be run for it to happen. AFAIK, there are separate adaptations, one for idle and another for mid/high loads, but not sure of all the conditions needed for the processes to activate.

The rear turbo inlet had nothing to do with a lean condition in one bank. The intake is common, both turbo outlets merge into a single tract before the IC and stay common through the intake manifold into the head. The only way one turbo could directly affect the bank it's on is from the exhaust side. By the same token, it's speed density and based on calculated airflow regardless of how much air is actually coming in and inlet on/off certainly isn't impacting AFR or trims in any large way. Actual airflow difference with inlet on/off is probably barely measurable, or not at all off boost, and would be averaged into the total airflow from both turbos on top of that, making the total impact even smaller. Either way, would not impact one bank and biggest issue would be pulling in unfiltered air.

I've hinted at what I think before and if it were my car, it would've been out of there a while ago. You seem pretty patient and there may always be something else they can think of to try, so long as there's a dollar left in your wallet to pay for it. At some point just have to start thinking it's beyond their ability...or they're just blowing smoke up your a$$. Not saying there can't be odd issues that are extremely difficult to find, but it's going on what, 5-6 weeks now?

Always possible there may be something else in the DME (maybe ignition mosfets instead or something else in it) and maybe a replacement would fix it, but seems they've supposedly fixed, replaced, checked or tested just about any obvious thing it could be at this point and either missed it or still haven't found it. At this point, DME is a $1400 crap shoot...will either fix it or it won't. If you're going to replace the DME either way, I'd find a cheap good used one (not sure if CAS is also needed?) just to test. Still some risk there, but if it fixed it, then consider buying new or making the switch to the relatively problem-free MSD81. If doesn't fix it, at least you're not out nearly as much for still no fix.

At some point, gotta take a step back and think it would be quicker and more cost effective taking it somewhere else that could definitively diagnose the problem without just throwing parts at it on your dime.

Believe me, had they not given me a decent free rental (an SUV which cured me of any desire to ever drive a vehicle w CVT in the future) for the past five weeks I'd have been out of there. I've spoken with the repair guy and the owners of the business are involved, because they *are* reputable and know that their reputation would take a major hit if they were being shady. Also, for some of the repairs (which were needed anyway, like the VCG) they're eating labor and putting it on basically at cost.

I don't fully understand what they've been telling me about the ECU other than that they've reset adaptations and despite that it still *thinks* the car is running lean, and is compensating, making it run rich. They put some kind of fuel analyzer on it (I'm spacing the name of the tool) to verify it. I've suggested switching to MSD81 but they've pushed back, saying that a new MSD80 would have the historical problems resolved.

They know their reputation is on the line here, especially since this is a small town. I (hope) trust they will do the right thing.

I'm beginning to think the f'ing Russians hacked my car.

[RSL]

Originally Posted by NavyBlues

Believe me, had they not given me a decent free rental (an SUV which cured me of any desire to ever drive a vehicle w CVT in the future) for the past five weeks I'd have been out of there. I've spoken with the repair guy and the owners of the business are involved, because they *are* reputable and know that their reputation would take a major hit if they were being shady. Also, for some of the repairs (which were needed anyway, like the VCG) they're eating labor and putting it on basically at cost.

I don't fully understand what they've been telling me about the ECU other than that they've reset adaptations and despite that it still *thinks* the car is running lean, and is compensating, making it run rich. They put some kind of fuel analyzer on it (I'm spacing the name of the tool) to verify it. I've suggested switching to MSD81 but they've pushed back, saying that a new MSD80 would have the historical problems resolved.

They know their reputation is on the line here, especially since this is a small town. I (hope) trust they will do the right thing.

I'm beginning to think the f'ing Russians hacked my car.

Just hoping they weren't taking you for a ride. It's doesn't even look like MSD80 can be purchased "new" anymore (all P/Ns supersede to MSD81), unless someone has some seriously old new stock sitting on the shelf. They haven't been used in 335s for 10 years. Thanks for confirming CAS is needed with it torrque.

Whatever it is, they certainly haven't found it yet. If you're going to do the DME, certainly hope that finally fixes it.

Stupid question, but what about putting the car on a dyno with a wideband to see what happens?

The car "thinking" it's lean and actually running lean are two different things. Getting an actual third-party reading might help answer the question.

[JuniorB]

Couple things, have you been running the car with high blend of ethonal? If so, it may take a few to run it back to normal. Since you done 02s, injectors, with no change, put a set of fresh plugs in, and a map sensor. Run the car for 50 miles and see if it clears it out. It's not an ECU, and with your issues, it won't do a dam thing.

[NavyBlues]

Originally Posted by RSL

Just hoping they weren't taking you for a ride. It's doesn't even look like MSD80 can be purchased "new" anymore (all P/Ns supersede to MSD81), unless someone has some seriously old new stock sitting on the shelf. They haven't been used in 335s for 10 years. Thanks for confirming CAS is needed with it torrque.

Whatever it is, they certainly haven't found it yet. If you're going to do the DME, certainly hope that finally fixes it.

And replacing the DME didn't fix it.

My goodness, I'm not sure what's left. The intake manifold pressure is running about 300-360 milibars when its supposed to be 400-500, and the multiplicative trim values are off. They ran a fine gas analyzer on it, and the exhaust doesn't reflect rich or lean fuel coming through, despite the warnings. They pulled the exhaust at the downpipes and pulled it back to take the cats completely out of the equation -- no change. They pulled the wiring harness apart and checked each pin looking for a loose pin, but nothing's out of the ordinary.

They brought in a friend who's a BMW tech at a dealership who also puzzled over it. This is the kind of thing that I think I'll have him write up for this site after the mystery is solved.

[NavyBlues]

Originally Posted by JuniorB

Couple things, have you been running the car with high blend of ethonal? If so, it may take a few to run it back to normal. Since you done 02s, injectors, with no change, put a set of fresh plugs in, and a map sensor. Run the car for 50 miles and see if it clears it out. It's not an ECU, and with your issues, it won't do a dam thing.

Thank you! I did get high ethanol gas somewhere (I suspect it was a nearby 7/11 -- jerks) and it was sitting around 20%. They dumped the fuel completely and replaced it w/ good gas.

[NavyBlues]

Originally Posted by FCobra94

Stupid question, but what about putting the car on a dyno with a wideband to see what happens?

The car "thinking" it's lean and actually running lean are two different things. Getting an actual third-party reading might help answer the question.

I'll check on the dyno, but they did run a fine gas analyzer on it, and the results did NOT reflect that it was running rich or lean.

[RSL]

I knew that was just going to be an expensive long shot

If they verified it's stoich AFR, but trims are skewed, only 2 options seem to be O2/DME value is jacked or there really is too much perceived oxygen in the exhaust post-cat. Can only assume at this point that they've done everything they said they did and did it competently, so will assume all O2s are working properly and readings are true. That means too much oxygen in the exhaust, which could still be a ton of things (misfires, injection issues, leaks, insufficient cat conversion, etc.).

Completely grasping as straws at this point...

- Any codes still occurring? If so, what are they? It may need to be run or even driven for some period to allow things to move enough for any potential code(s) to set.
- Did they replace the PCV valve/hose when they did the VC?
- Was the car at temp, no accessories, etc. when they tested vacuum?
- Did they verify VANOS position/actuation for the vacuum test? Cam overlap will obviously impact engine vacuum.
- Compression/leak down to verify cylinders, head gasket, injectors are sealed in the head, etc.
- New seals used when they swapped the injectors? Did the injectors that were originally in there show any signs of blow-by (combustion leaking out past the seals)?
- Verify all grounds are good?
- May not help, but IIRC, you can turn off injectors by cylinder in INPA. Could turn off one cylinder at a time in bank 2 and note lambda for the bank with each cylinder off. If there is a noticeable difference in how far lambda drops (or doesn't drop) with one off compared to the others off, that injector or cylinder has a potential problem with combustion and you know where to focus.
- The "rough run" strategy might also be something to look at for a quick indication of a potential cylinder issue, but I honestly haven't paid a whole lot of attention to it. There is a screen for it in INPA as well and it's an individual cylinder compensation, so if a value is way out in left field relative to 0 and the other cyls, might be a quick indication where to focus.

[NavyBlues]

Originally Posted by RSL

I knew that was just going to be an expensive long shot

If they verified it's stoich AFR, but trims are skewed, only 2 options seem to be O2/DME value is jacked or there really is too much perceived oxygen in the exhaust post-cat. Can only assume at this point that they've done everything they said they did and did it competently, so will assume all O2s are working properly and readings are true. That means too much oxygen in the exhaust, which could still be a ton of things (misfires, injection issues, leaks, insufficient cat conversion, etc.).

Completely grasping as straws at this point...

- Any codes still occurring? If so, what are they? It may need to be run or even driven for some period to allow things to move enough for any potential code(s) to set.
- Did they replace the PCV valve/hose when they did the VC?
- Was the car at temp, no accessories, etc. when they tested vacuum?
- Did they verify VANOS position/actuation for the vacuum test? Cam overlap will obviously impact engine vacuum.
- Compression/leak down to verify cylinders, head gasket, injectors are sealed in the head, etc.
- New seals used when they swapped the injectors? Did the injectors that were originally in there show any signs of blow-by (combustion leaking out past the seals)?
- Verify all grounds are good?
- May not help, but IIRC, you can turn off injectors by cylinder in INPA. Could turn off one cylinder at a time in bank 2 and note lambda for the bank with each cylinder off. If there is a noticeable difference in how far lambda drops (or doesn't drop) with one off compared to the others off, that injector or cylinder has a potential problem with combustion and you know where to focus.
- The "rough run" strategy might also be something to look at for a quick indication of a potential cylinder issue, but I honestly haven't paid a whole lot of attention to it. There is a screen for it in INPA as well and it's an individual cylinder compensation, so if a value is way out in left field relative to 0 and the other cyls, might be a quick indication where to focus.

More...

Been working on your 335 for a couple of hours now. Started pulling some of the wiring harness looms apart looking for anything out of the ordinary, haven't found anything yet unfortunately. I read through the ideas you sent. I can deactivate individual cylinders as needed, but unfortunately it makes the values go even further lean on whichever bank you are deactivating a cylinder on.

Interestingly, at times I can be standing there with the fuel trim values right in front of me, and randomly one bank will go to a normal trim range. Then after a few minutes it will jump back up to +30%. Then a while later the other bank will follow suit.

It seems that across the board when you look at the smooth running values are just all over the place. Perhaps this is just due to the DME compensating for what it perceives as a lean condition.

[RSL]

The smoothing values are per cylinder and IIRC, higher/positive numbers will indicate an inefficiency in a cylinder relative to the others. So, if you have 5 cyls with negative values and 1 with a positive, the one with the positive might bear looking into. Also, IIRC, if there are misfires in a cylinder, the value hangs at 0 momentarily.

For sure, dropping a cylinder will cause the bank to run lean and the motor run like crap. The idea was to compare the bank value with each cylinder off to determine if there is any large disparity with one of them off. Either case is just "a" way to peek for potential individual cylinder problems without getting dirty, but there are more sure-fire ways. They were just something I remembered seeing and coughed up

The prior code was just for bank 2, but the new info is that the full trim is on/off and full alternates between banks? I know I keep coming back to O2s, but I just can't get away from that it smacks of reading problems if everything else is working as it should.

- Are they 1000000% sure the primary O2s are connected into their correct corresponding connectors? That flip/flop full trim waffling between banks can/does occur when the primaries are plugged in backwards and the DME is trying to trim one bank based on info from the other bank.
- Are they reading it during cat/O2 heating process or after full temps are reached for everything?
- Wondering if some adaptation is working on them. There are also several different fuel modes that are run through during starts and warm-up phases and as I mentioned before, there is an idle adaptation for fueling as well, but I don't know the conditions for when it runs.
- Have they driven the car at all or is this only being tested at idle?

[NavyBlues]

Originally Posted by RSL

The smoothing values are per cylinder and IIRC, higher/positive numbers will indicate an inefficiency in a cylinder relative to the others. So, if you have 5 cyls with negative values and 1 with a positive, the one with the positive might bear looking into. Also, IIRC, if there are misfires in a cylinder, the value hangs at 0 momentarily.

For sure, dropping a cylinder will cause the bank to run lean and the motor run like crap. The idea was to compare the bank value with each cylinder off to determine if there is any large disparity with one of them off. Either case is just "a" way to peek for potential individual cylinder problems without getting dirty, but there are more sure-fire ways. They were just something I remembered seeing and coughed up

The prior code was just for bank 2, but the new info is that the full trim is on/off and full alternates between banks? I know I keep coming back to O2s, but I just can't get away from that it smacks of reading problems if everything else is working as it should.

- Are they 1000000% sure the primary O2s are connected into their correct corresponding connectors? That flip/flop full trim waffling between banks can/does occur when the primaries are plugged in backwards and the DME is trying to trim one bank based on info from the other bank.
- Are they reading it during cat/O2 heating process or after full temps are reached for everything?
- Wondering if some adaptation is working on them. There are also several different fuel modes that are run through during starts and warm-up phases and as I mentioned before, there is an idle adaptation for fueling as well, but I don't know the conditions for when it runs.
- Have they driven the car at all or is this only being tested at idle?

Smooth running values are cylinder contribution to crankshaft rotation. Zero is perfect world. Perfect scenario. Negative indicates less than expected contribution, positive indicates more than expected contribution. Usually -4 or more is a dead miss that the DME actually picks up as a misfire (and then cuts that cylinder's fuel injector).

I'm starting to wonder if I should have put all 4 oxygen sensors in that car at the same time. We had an x5 with an older naturally aspirated engine a while back that absolutely would not stop throwing this odd out of this world oxygen sensor code that made no sense until we put all 4 sensors in at once. Even though the fault was only for one sensor pre catalyst.

[RSL]

Correct, the cylinders are identified by the crankshaft segment and efficiency is segment over time, but I couldn't remember the polarity. Any outliers from the general range of values should be sort of obvious if there were a problem in one though.

I'll keep thinking on it, but the trim issue gets stranger the more info that comes out, especially if they are all definitely connected correctly. At this point, I'm just in it finally find out WTF it is lol

[NavyBlues]

Originally Posted by RSL

Correct, the cylinders are identified by the crankshaft segment and efficiency is segment over time, but I couldn't remember the polarity. Any outliers from the general range of values should be sort of obvious if there were a problem in one though.

I'll keep thinking on it, but the trim issue gets stranger the more info that comes out, especially if they are all definitely connected correctly. At this point, I'm just in it finally find out WTF it is lol

Yes the primaries are connected to the correct connector - I did an "idiot" check on that the other morning mostly out of sheer what the hell..... Switched them. Man that thing got mad instantly. And threw the code I knew it would throw..... Oxygen sensors reversed.

[Julian2485]

Originally Posted by NavyBlues

Yes the primaries are connected to the correct connector - I did an "idiot" check on that the other morning mostly out of sheer what the hell..... Switched them. Man that thing got mad instantly. And threw the code I knew it would throw..... Oxygen sensors reversed.

Did you find fix yet ?

[NavyBlues]

Originally Posted by Julian2485

Did you find fix yet ?

Not yet. Going wire by wire through the harness is taking some time. I'm hopeful though.

[BMWhartgeM3]

Man oh man! I've been dealing with the same exact issue you are! I've walked basically the same path, replaced injectors, plugs, coils, both rear O2's, sealed all boost leaks, all the vacuum lines upgraded PCV valve. I also replaced Tmap, and Boost Solenoids which I didn't see mention and feel like it might at least be worth mentioning.
Im subscribing though, I hope one of us are able to correct the issue, and that it will be the same issue...good luck!

[NavyBlues]

So here's the abridged version, I'll have more details over the next couple of days. They took their BMW tech off of it and gave the car to their head diagnostician who went to work on it a week ago.

Turns out one of the injectors was bad, and the injector fried the DME. So for that reason when they swapped out the injectors with 'known good' injectors, that didn't fix it, and when they just swapped DME's that didn't do it either. So now it's got MSD81 and a fresh set of injectors and she is purring like a LION again. Seriously, maybe it's the bs rental CVT 4-banger CUV I've been driving the last two months, but she seems faster than I can remember her being since she was but a babe. She still looks awfully hot for 105.

[Wolf 335]

Originally Posted by NavyBlues

So here's the abridged version, I'll have more details over the next couple of days. They took their BMW tech off of it and gave the car to their head diagnostician who went to work on it a week ago.

Turns out one of the injectors was bad, and the injector fried the DME. So for that reason when they swapped out the injectors with 'known good' injectors, that didn't fix it, and when they just swapped DME's that didn't do it either. So now it's got MSD81 and a fresh set of injectors and she is purring like a LION again. Seriously, maybe it's the bs rental CVT 4-banger CUV I've been driving the last two months, but she seems faster than I can remember her being since she was but a babe. She still looks awfully hot for 105.

Glad you resolved this, and I hope this is not the case with my lean fault.

How much was the cost?