Unsolvable Lean Condition/CEL - Not sure where to go from here

[thejacko5]

Hi All,

Obviously new here, though i have lurked around prior to today.

I have a story share in hopes of getting some advice on what to do next. Its been a saga so far.

2014 F10 - 42,0XX miles.

I purchased this car used about 5 years ago. It is driven sparingly (cant be my DD) and spends the winter in hibernation. I take care of it.

This spring i decided to treat myself by having the front and rear bumper, hood, and side skirts repainted and protected. Lots of chipping and paint distress, it never had a clear bra. A great local euro car paint specialist. She's looking good.


My plan has been to keep this car for some time.

Early july i decided, ok , its time to do a few things. Pick up some PG intakes and downpipes with the BM3 license.

While the order from PG was cooking I also ordered a new set of rubber.

Order is on its way from PG. Tires ship and get to the shop the day before. I decide to put the tires on first. Jump in the car to go to the shop. Stop for gas on the way. Start the car back up and boom, CEL and drivetrain malfunction.

I've been pretty diligent about getting work done at the dealer, even after warranty expired, just for the paper trail if i ever decided to sell.

I also want the computer clean and the car gone through before doing modifications or BM3.

So I abort the tire install and head to the dealership. This is July 15th.

I am going to rewrite the written notes, numbered below, outlining the steps they have taken to date.


1. On initial diagnosis, faults noted for rail pressure implausible on startup along with lean mixture on both banks and intermittent misfires. Diagnosis determined Bank 2 rail sensor is faulty

They tell me it is probably the sensor but if not, they will want to replace the HPFP. $475 for the sensor and $1600 for the HPFP.

Monday the part comes in and they do the fix by Tuesday. CEL is gone and stays gone during the test drive. They bring it back in, let it set, and go for a second start up, CEL is back.

On Wednesday (7/20) they ask to keep the vehicle another day because

"we are still having a similar issue. Drivetrain malfunction is gone but the vehicle is still lacking power."

Apparently, with the sensor replaced and some more testing they have determined that the HPFP is not at fault. They continue:

2: After rail pressure sensor replacement test drove car and faults related to Bank 1 airflow sensor were stored. Performed related test plan which indicated Bank 1 airflow sensor faulty. MAF sensor replaced.

On Friday (1 week), the service manager gets involved and gives me a call. Explains to me that they havent been able to clear the CEL. It always returns on the second startup and they arent sure what the issue is. He tells me they want to do some more diagnostic tests and that they are going cover the cost of this work because its taking some time and now they are starting become unsure of where the problem is. This is where it turns into trial and error for them.

They talk to the regional BMW engineer and he suggest the following as the next step.

3. Replaced both CCV valves as a test measure. Deleted old adaptation values, test drove the car and rechecked. Noted faults for Bank 1 mixture lean stored. CEL is back.

So with the lean mixture continuing to register, they start looking for leaks.

4. Performed leak test on intake with smoke machine as per test plan and found Bank 2 turbo inlet duct leaking. Replaced Bank 2 turbo inlet duct and clamps and retest. Leak mixture fault returned during test drive.

5. Performed leak test on exhaust system with smoke machine as per test plan and found leaks at catalytic converter downpipes lower seals. Replaced exhaust gaskets and recheck. Lean mixture faults still present.

So no leaks in front or behind. They move to more sensory and computer diagnostics.

6. During diagnosis noted rail pressure on Bank 1 leaks down rapidly compared to bank 2 after engine shut off. Contacted TSE (BMW Engineer) and was advised to replace HPFP for Bank 1. After HPFP replacement and test, leak mixture faults returned.

----This is probably two weeks elapsed at the dealer----Its clear that the lean mixture is only occurring on Bank 1. I think the idea of the following steps is to rule out electronic/sensor issues between twin parts on the car. If its a sensor or electronic issue, swapping the parts to opposite sides should rule out or rule in electronics.

7. As per TSE's recommendation, swapped and coded DME's, swapped air flow sensors, swapped pre cat o2 sensors, swapped post cat o2 sensors. After each step, lean mixture faults on Bank 1 returned.

Now this is a big one....probably a week or so ago, three weeks in.

8. Replaced all 8 fuel injectors as per TSE's recommendation. Performed injector calibration run and deleted stored adaptation values. Lean mixture faults returned during test drive.

On this step, the Shop Foreman (who i spoke to today-more on this later), said that he removed and cleaned the plugs as good practice at this step - although it isnt written down in the report i and copying into this post. he said they were in good condition, a little dirty, but fine - so he cleaned them up and reinstalled.

He did note that he pulled the plugs again after this test drive and the Bank 1 plugs were blackened - moreso than the Bank 2 plugs that are not lean. More on this later.

So its not intake air, its not exhaust air (we think), and its not fuel system - so lets check the engine.

9. Performed compression and leakdown tests and found that all cylinders fall within min specs (190 psi and less than 5% leakage)

10. As per TSE, connected breakout box at DME's 1 & 2. Monitored injector signal with occiloscope to evaluate DME's ability to compensate for mixture variation and found both DME's responding correctly.

11. Performed boroscope inspection of catalytic converters, no abnormalities observed.

12. As per TSE, removed intercoolers for internal inspection. No defects found.

Step 12 was last week. The service manager, who had been calling me every couple days to give up dates, gives me a call to tell me that they have exhausted all possible options and that they reached out to the national engineering office to see if someone would be willing to get involved.




That brings us to today (8/16), one week after this phone call, where I get a message from the service manager asking me to come in to talk about everything they have done.

After work i head over there. The service manager is busy with another customer, but the shop foreman comes to see me and takes me through all of these steps.

He is completely baffled by the issue and says he has never taken all of these steps on a car and it not cleared the issue.

He throw out an interesting, plausible theory.

When he pulled the plugs after the test drive following the injector replacement (step 8 above), he did note that the plugs were blackened. He said that would tell him that the engine is registering too much o2 and the computer is compensating by increasing fuel. Hence the quickly blackened plugs. He floated an idea of a hairline crack in the headers/downpipes that would allow excess oxygen to get into the exhaust prior to the o2 sensor. This would tell the DME that the mixture is too lean, and add fuel.

He also said, but didnt write down, that he could sense misfires at idle. "Idling a little rough". Further, he said that when he stepped on it during the test drive, it would experience some power loss or "fluttering" of power. He also said that in order to truly pressure test the manifold/downpipes, they would need to be removed so they could be properly sealed in order see results - which makes sense because you need pressure to leak test.

At this point, the service manager came in.

I will give him credit that up until this point he handled himself really well from a customer service standpoint. I had his direct line, he provided updates, and they did perform a lot of work. I even dropped off the new tires with him because he offered to put them on for me while it was in the shop.

However, at this point that kinda turned off.

He told me flatly that they don't know what is wrong with this car, they cannot fix it, and they have to stop working on it.

He then went as far to suggest that I should find a high performance shop somewhere to do the work because they might have some better ideas. (kinda shocked to hear this from a dealer because they are usually whores).

BMW isnt getting involved any further because the car is not under warranty. They also wont offer a buyback (not that I want to sell it, I want to keep this girl).

He said the best they could do is try to sell it at auction, obviously with some disclaimers that it has unsolvable issues. Cant/Dont want this either.

We ended it by me telling him that I cant accept the car back with the repair not done and that I cant believe they wont even continue to pursue this with BMW engineers. With the CEL i cant get inspection, etc.

Obviously, the car is out of warranty, so I am not sure how hard I can push back on them, considering the work they have done.

But to completely PUNT?! Money notwithstanding, its a weird tac to take after a months work already put into it.

So at this point I am not sure what to do. The idea of a leak post engine and pre o2 sounds like a real possibility.

I guess being out of warranty, it doesn't really matter who does the work. I just wish we had a better idea where to look for the issue.


Any thoughts from folks here is greatly appreciated.

J

[M5_Raz]

Service guy is right, dealerships suck at working on these cars. I had a similar issue with 2 performance bmw shops and my local dealership. Nobody could figure it out until I took it to Steve Dinan's shop, Carbahn Autoworks.

Idk what I would've done if I was in a part of the country/world where I didn't have so many options.

[M5Rick]

Originally Posted by thejacko5

Hi All,

Obviously new here, though i have lurked around prior to today.

I have a story share in hopes of getting some advice on what to do next. Its been a saga so far.

2014 F10 - 42,0XX miles.

I purchased this car used about 5 years ago. It is driven sparingly (cant be my DD) and spends the winter in hibernation. I take care of it.

This spring i decided to treat myself by having the front and rear bumper, hood, and side skirts repainted and protected. Lots of chipping and paint distress, it never had a clear bra. A great local euro car paint specialist. She's looking good.


My plan has been to keep this car for some time.

Early july i decided, ok , its time to do a few things. Pick up some PG intakes and downpipes with the BM3 license.

While the order from PG was cooking I also ordered a new set of rubber.

Order is on its way from PG. Tires ship and get to the shop the day before. I decide to put the tires on first. Jump in the car to go to the shop. Stop for gas on the way. Start the car back up and boom, CEL and drivetrain malfunction.

I've been pretty diligent about getting work done at the dealer, even after warranty expired, just for the paper trail if i ever decided to sell.

I also want the computer clean and the car gone through before doing modifications or BM3.

So I abort the tire install and head to the dealership. This is July 15th.

I am going to rewrite the written notes, numbered below, outlining the steps they have taken to date.


1. On initial diagnosis, faults noted for rail pressure implausible on startup along with lean mixture on both banks and intermittent misfires. Diagnosis determined Bank 2 rail sensor is faulty

They tell me it is probably the sensor but if not, they will want to replace the HPFP. $475 for the sensor and $1600 for the HPFP.

Monday the part comes in and they do the fix by Tuesday. CEL is gone and stays gone during the test drive. They bring it back in, let it set, and go for a second start up, CEL is back.

On Wednesday (7/20) they ask to keep the vehicle another day because

"we are still having a similar issue. Drivetrain malfunction is gone but the vehicle is still lacking power."

Apparently, with the sensor replaced and some more testing they have determined that the HPFP is not at fault. They continue:

2: After rail pressure sensor replacement test drove car and faults related to Bank 1 airflow sensor were stored. Performed related test plan which indicated Bank 1 airflow sensor faulty. MAF sensor replaced.

On Friday (1 week), the service manager gets involved and gives me a call. Explains to me that they havent been able to clear the CEL. It always returns on the second startup and they arent sure what the issue is. He tells me they want to do some more diagnostic tests and that they are going cover the cost of this work because its taking some time and now they are starting become unsure of where the problem is. This is where it turns into trial and error for them.

They talk to the regional BMW engineer and he suggest the following as the next step.

3. Replaced both CCV valves as a test measure. Deleted old adaptation values, test drove the car and rechecked. Noted faults for Bank 1 mixture lean stored. CEL is back.

So with the lean mixture continuing to register, they start looking for leaks.

4. Performed leak test on intake with smoke machine as per test plan and found Bank 2 turbo inlet duct leaking. Replaced Bank 2 turbo inlet duct and clamps and retest. Leak mixture fault returned during test drive.

5. Performed leak test on exhaust system with smoke machine as per test plan and found leaks at catalytic converter downpipes lower seals. Replaced exhaust gaskets and recheck. Lean mixture faults still present.

So no leaks in front or behind. They move to more sensory and computer diagnostics.

6. During diagnosis noted rail pressure on Bank 1 leaks down rapidly compared to bank 2 after engine shut off. Contacted TSE (BMW Engineer) and was advised to replace HPFP for Bank 1. After HPFP replacement and test, leak mixture faults returned.

----This is probably two weeks elapsed at the dealer----Its clear that the lean mixture is only occurring on Bank 1. I think the idea of the following steps is to rule out electronic/sensor issues between twin parts on the car. If its a sensor or electronic issue, swapping the parts to opposite sides should rule out or rule in electronics.

7. As per TSE's recommendation, swapped and coded DME's, swapped air flow sensors, swapped pre cat o2 sensors, swapped post cat o2 sensors. After each step, lean mixture faults on Bank 1 returned.

Now this is a big one....probably a week or so ago, three weeks in.

8. Replaced all 8 fuel injectors as per TSE's recommendation. Performed injector calibration run and deleted stored adaptation values. Lean mixture faults returned during test drive.

On this step, the Shop Foreman (who i spoke to today-more on this later), said that he removed and cleaned the plugs as good practice at this step - although it isnt written down in the report i and copying into this post. he said they were in good condition, a little dirty, but fine - so he cleaned them up and reinstalled.

He did note that he pulled the plugs again after this test drive and the Bank 1 plugs were blackened - moreso than the Bank 2 plugs that are not lean. More on this later.

So its not intake air, its not exhaust air (we think), and its not fuel system - so lets check the engine.

9. Performed compression and leakdown tests and found that all cylinders fall within min specs (190 psi and less than 5% leakage)

10. As per TSE, connected breakout box at DME's 1 & 2. Monitored injector signal with occiloscope to evaluate DME's ability to compensate for mixture variation and found both DME's responding correctly.

11. Performed boroscope inspection of catalytic converters, no abnormalities observed.

12. As per TSE, removed intercoolers for internal inspection. No defects found.

Step 12 was last week. The service manager, who had been calling me every couple days to give up dates, gives me a call to tell me that they have exhausted all possible options and that they reached out to the national engineering office to see if someone would be willing to get involved.




That brings us to today (8/16), one week after this phone call, where I get a message from the service manager asking me to come in to talk about everything they have done.

After work i head over there. The service manager is busy with another customer, but the shop foreman comes to see me and takes me through all of these steps.

He is completely baffled by the issue and says he has never taken all of these steps on a car and it not cleared the issue.

He throw out an interesting, plausible theory.

When he pulled the plugs after the test drive following the injector replacement (step 8 above), he did note that the plugs were blackened. He said that would tell him that the engine is registering too much o2 and the computer is compensating by increasing fuel. Hence the quickly blackened plugs. He floated an idea of a hairline crack in the headers/downpipes that would allow excess oxygen to get into the exhaust prior to the o2 sensor. This would tell the DME that the mixture is too lean, and add fuel.

He also said, but didnt write down, that he could sense misfires at idle. "Idling a little rough". Further, he said that when he stepped on it during the test drive, it would experience some power loss or "fluttering" of power. He also said that in order to truly pressure test the manifold/downpipes, they would need to be removed so they could be properly sealed in order see results - which makes sense because you need pressure to leak test.

At this point, the service manager came in.

I will give him credit that up until this point he handled himself really well from a customer service standpoint. I had his direct line, he provided updates, and they did perform a lot of work. I even dropped off the new tires with him because he offered to put them on for me while it was in the shop.

However, at this point that kinda turned off.

He told me flatly that they don't know what is wrong with this car, they cannot fix it, and they have to stop working on it.

He then went as far to suggest that I should find a high performance shop somewhere to do the work because they might have some better ideas. (kinda shocked to hear this from a dealer because they are usually whores).

BMW isnt getting involved any further because the car is not under warranty. They also wont offer a buyback (not that I want to sell it, I want to keep this girl).

He said the best they could do is try to sell it at auction, obviously with some disclaimers that it has unsolvable issues. Cant/Dont want this either.

We ended it by me telling him that I cant accept the car back with the repair not done and that I cant believe they wont even continue to pursue this with BMW engineers. With the CEL i cant get inspection, etc.

Obviously, the car is out of warranty, so I am not sure how hard I can push back on them, considering the work they have done.

But to completely PUNT?! Money notwithstanding, its a weird tac to take after a months work already put into it.

So at this point I am not sure what to do. The idea of a leak post engine and pre o2 sounds like a real possibility.

I guess being out of warranty, it doesn't really matter who does the work. I just wish we had a better idea where to look for the issue.


Any thoughts from folks here is greatly appreciated.

J

This with a completely stock car. If it happened just after gassing up it could be that bad gas is suspect number one.
What gas did you use if you don't mind saying.

[thejacko5]

Originally Posted by M5Rick

This with a completely stock car. If it happened just after gassing up it could be that bad gas is suspect number one.
What gas did you use if you don't mind saying.

Yes, completely stock.

always 93. 94 if i can find it.

A friend of mine did suggest this and I passed it on to them. The one thing that makes me rule it out is that it is all on Bank 1.

I would think that bad fuel would register everywhere or more widely.

[M5Rick]

All injectors replaced too, I'm finding that from others who had this happen it can go back to one particular thing which fault finding hand held OBD 2 and others can't trace but pull up codes as an extension only to the underlying cause.
We have an experienced technician who comes on not that often but I suggest if you're really stuck to give this Dinan,Carbahn Autoworks a call whom M5_Raz used.

[thejacko5]

Originally Posted by M5_Raz

Service guy is right, dealerships suck at working on these cars. I had a similar issue with 2 performance bmw shops and my local dealership. Nobody could figure it out until I took it to Steve Dinan's shop, Carbahn Autoworks.

Idk what I would've done if I was in a part of the country/world where I didn't have so many options.

If i had that garage as an option, I would probably be there today.

Unfortunately, I am in NJ and I am not even sure who the best person would be in this area to take a look at this.

I think that if the consensus is to forget trying to fix things at the dealer, the next step is a BMW specialist shop.

[thejacko5]

Originally Posted by M5Rick

All injectors replaced too, I'm finding that from others who had this happen it can go back to one particular thing which fault finding hand held OBD 2 and others can't trace but pull up codes as an extension only to the underlying cause.
We have an experienced technician who comes on not that often but I suggest if you're really stuck to give this Dinan,Carbahn Autoworks a call whom M5_Raz used.

Meaning, the diagnosis of the problem is only as good as the tech who is looking at the OBD2 readouts?

[M5Rick]

Originally Posted by thejacko5

Meaning, the diagnosis of the problem is only as good as the tech who is looking at the OBD2 readouts?

Sometimes there's no easy answer, I wish it could be easier but yes in some cases it needs an experienced tech to oversee what is bringing up codes and I carry a cheap OBD 2 that I have used to cancel a yellow engine management light a couple times and the dealer said it's nothing probably a fuel cap vent pipe thing.

[thejacko5]

Originally Posted by M5Rick

Sometimes there's no easy answer, I wish it could be easier but yes in some cases it needs an experienced tech to oversee what is bringing up codes and I carry a cheap OBD 2 that I have used to cancel a yellow engine management light a couple times and the dealer said it's nothing probably a fuel cap vent pipe thing.

I sent out an email to the Carbahn shop just outlining the situation and asking them if they have any ideas and if they can recommend a shop in this area.

A recommendation from them would be as good as gold from where i sit right now.

Its a shot in the dark, but I really dont know what to do or where to take this thing now.

[M5Rick]

^ 'Still lacks power' Check the vac pipes as these can cause power loss if bad or loose and bring up CEL, GL.

[thejacko5]

I guess as an aside, if anyone on this board is in NJ area and can recommend a good BMW shop worth taking this car to, i would appreciate that as well.

Thanks

[pleadbymail]

Motorcepts in queens have been my "bmw" specialist shop in the area.

I cant recommend a NJ shop out of experience but I do see some near 5 star shops that might have some knowledge. "Motor Works West"

[thejacko5]

Originally Posted by pleadbymail

Motorcepts in queens have been my "bmw" specialist shop in the area.

I cant recommend a NJ shop out of experience but I do see some near 5 star shops that might have some knowledge. "Motor Works West"

Thanks,

I did reach out to Motor Works West. They do seem to be legit. BMW only shop and authorized distributor and installer for Dinan (hopefully that is worth something).

They can take the car on 9/6. So they must be busy, which is a good sign.

[thejacko5]

actually, interesting update this morning.

i had called the dealership after they punted and i left the service manager a VM telling him that i cant accept the car back from them. it is not drivable, cant be inspected, and they provided no options for me or suggestions. obviously i said that this is totally unacceptable.

today i get a call back from them that they went back to BMWNA and they have now offered to set additional support to work on this car.

I guess for now I am going to let it ride with them and see what they do.

[pleadbymail]

Which dealer are you having this pup worked at?

[thejacko5]

Originally Posted by pleadbymail

Which dealer are you having this pup worked at?

BMW Bridgewater (NJ)

[thejacko5]

so, after leaning on the dealership they are actually doing more work.

they pulled off the turbos and they also pulled of the exhaust manifold.

behold, they found a crack at one of the weldments. they are not sure if the crack propagated all the way through the base material but, a crack there could be a way for the exhaust to pull fresh air into the exhaust before the o2 sensor. That excess air would make the sensor pick up more o2 and think the engine is lean.

visual inspection of plugs indicates rich.

so all that makes sense.

[M5_Raz]

Any more updates?

[Alrock31]

.

[thejacko5]

Originally Posted by M5_Raz

Any more updates?

so, we have conclusion on the issue. I picked the car up at the end of last week and everything is butter.

the crack in the exhaust manifold was the problem. the crack was allowing outside air to get pulled into the exhaust system pre o2 sensor, throwing a lean condition that was causing more fuel to be incorrectly added to the mix and creating an ACTUAL rich condition.


CEL has cleared and the car is running great.

they replaced the manifold and associated bolts and gaskets.


at the end of the day that is all they charged me for

$1050 for the manifold plus the labor (about 12 hours) and misc hardware.

total with taxes and everything was $3600.

they did NOT charge me for the following work:

replacement of MAF sensors
replacement of high pressure fuel pumps
replacement of injectors (all 8).
replacement of plugs
replacement of pre and post cat o2 sensors
all of the diagnostics and testing done up until the actual fix.


overall I think this is a huge win considering how much work was done on the house.

I am really impressed that this dealership hung in there. I have experienced and heard of so many dealership horror stories over the years that my expectations were really low.

BMW Bridgewater in NJ is a good egg.