Rough idle with high AFRs after start

335is

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Nov 4, 2019
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335is
Any guesses what could cause such issue on 335is MT?
After car is started (no matter hot or cold, time between hot starts does not matter also), idle is rough, after couple of seconds AFRs go to ~20s and stay there. Solution is to press accelerator pedal, hold it steady in one position, wait for 15-30 seconds and AFRs go back to normal and car can idle without issues. If I do not press accelerator that issue does not go away by itself.

Following errors are thrown from time to time: 2D2B & 2D2E. I have tried doing adaptations reset with ProTool and complete reflash of a car, neither helped. Recently a lot of tuning parts were installed, one of them rbturbo external PCV kit with head plugs was installed, since it is connect to throttle I think that it can have some effect.

I have uploaded a log that was recorded at the same time as a video:
https://datazap.me/u/voroninpy/335i...rs?log=0&data=2-8-9-16-19&solo=3&mark=342-482

 
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335is

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Could be Injectors, have you checked what version you have?
I doubt it is injectors because I have index 12 and time period between engine starts does not have any effect on this issue, and from what I know the longer engine sits the more injectors leak.
 

335is

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I had my throttle body die recently and it looked pretty close to what you are experiencing.

Did you have any other symptoms or maybe you know about some way that this can be verified to be 100% sure that issue is with throttle body?
 

335is

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Update about this issue - when I do unplug second map sensor (the one that is in manifold) issue completely disappears. I tried cleaning that sensor with maf cleaner, it does not help. Has anyone heard about those sensors failing? I don't want to buy new one to find out that issue is with something else. I also did change my tmap sensor and switched from 4 to 3.5 bar, this changed two things - cold start is no longer very harsh, car can stabilize itself when RPMs are high during warmup, hot start no longer stalls the car, idle is still rough but not as bad as it was with 4 bar tmap.

Regarding vacuum, I did check it while car was idling and I have 28,5 inHg when I connect to a nipple that is near oil filter, that value seems fine.

I also did replace all vacuum lines going from those nipples to wastegates (did this while was chasing other issue). Also I did remove RB external PCV valve from engine cover and throttle body. But none of that did not effect situation in any way.
 

martymil

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28.5 in Hg is way to high for manifold vacuum your measuring vacuum pump vacuum.

Manifold vacuum you can see from MHD or disconnect the dv line from the manifold and plug the gauge straight into it to measure.
 

335is

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28.5 in Hg is way to high for manifold vacuum your measuring vacuum pump vacuum.

Manifold vacuum you can see from MHD or disconnect the dv line from the manifold and plug the gauge straight into it to measure.

Do you know what is the normal value? I found a thread that says 19-21 is normal.

I will check it with vacuum gauge, but just out of curiosity, what data logging option should I select in MHD to see that value? Should it be some boost mean or smth, because I assume regular boost will show boost in chargepipe not manifold.
 

335is

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Boost gauge reads vacuum on mhd at idle it should read anywhere between 9 to 11 in Hg
Checked logs and mine is 8.4 at 700RPM and 10.9 when I turn off engine, I guess that indicates that there is a leak between engine and tmap sensor. Thanks for help, will be searching for it.
 

martymil

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Not necessarily, what indicates a vacuum leak at idle is the 20 afr but if it runs fine by disconnecting the sensor you might have an electrical issue or the sensor is stuffed
 

Oliver805

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Dec 30, 2018
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Did you ever figure out the problem ? I’m having the same issue getting 2d2e code idle really bad
 

335is

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Did you ever figure out the problem ? I’m having the same issue getting 2d2e code idle really bad
TL:DR; I replaced second MAP sensor with new one P/N: 13627585492 and issue went away.

Yes, I did take second map sensor from different N54 car for a test and issue was gone. Interesting thing that my sensor did not look like the one from other car and part numbers did not match. Part number from that other car was 13627560063, but mine had 759904201 which is likely from N55, because I did check realoem catalog and the one I should have is 13627585492, it replaces 13627560063, which was deprecated in 2009.

I don't know how the fuck I ended up with 759904201, my guess is that shop that was installing all the tuning parts (PI with Phoenix manifold including) messed up and either broken my sensor and ordered incorrect replacement and did not tell me about it, or they they just mixed it up.
 

AWS

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Jan 12, 2022
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Good morning,
Did you solve the idle problem.
Cause I have the same idle fluctuates in my e93 N54 engine may some time reach to stall..
 

martymil

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Idle fluctuations are usually caused by a o2 sensor starting to go bad or a leaking injector its that simple.