[TheBigChill]

Hey guys,

First and foremost, I own a 2009 128i M-Sport. Yes, I know- this is the E90 forum. I've come here from 1Addicts.com because most forum members there own 135i's, so I figured I'd leverage the N52 crowd from E90Post.

The car: 2009 128i, 6MT, 75k miles.

Mods: Only relevant mod is an AFE intake.

Codes: 29E0 "Mixture Control Bank 1"
29E1 "Mixture Control Bank 2"

Generic P0172 and P0175 (Banks 1 & 2 Rich) also exist.

Diagnostics thus far:
Short Term Fuel Trim @ Idle
Bank 1: -2% through +2%
Bank 2: -4% through 0%

Long Term Fuel Trim @ Idle
Bank 1: -17%
Bank 2: -25%

Long Term Fuel Trim @ Cruise
Neither bank goes above -10.2% no matter what


MAF Flow Rate
3.4 g/sec @ idle
160 g/sec @ WOT (Seems low. should be 80% of car's HP, so ~190 g/sec)

Fuel Pressure
70psi on rail @ idle. Spec is 72.

Rear O2 Voltage
Bank 1 .70v
Bank 2 .68v

Widerange O2 Equivelancy
1 I believe this means that a stoichiometric mix is being maintained
successfully.

More Info:
Car Idles fine.
Seems to have decent power.
No odd smoke at idle or while cruising.
Haven't checked plugs yet for wetness.

Any info you can contribute is appreciated. Could someone with an N52 log their MAF at both idle and WOT 3rd gear?

I smoke tested the car as well, and found a tiny leak at the rear ground stud on the valve cover. I'll fix that, but it can't be the cause of this, as a this would cause an unmetered vac leak, and cause a lean condition and + fuel trims. I have the exact opposite issue. I've been unable to log primary O2 sensors thus far, as Torque Pro doesn't support Wideband sensors. I have Carly, but it won't allow me to log parameters because I use an ELM327 and not their adapter.

[hassmaschine]

If you have a laptop and a D-CAN cable, try logging with Testo.

[TheBigChill]

I don't have a D-Can cable. Also, what would you suggest that I monitor beyond what I already have? I feel like I've presented a fair amount of info as to the readings I'm getting.

[hassmaschine]

well, if you wanted to monitor the wideband loop - that would be the best way to log.

what happens if you reset adaptations? does it immediately go back to -25% trim? IIRC 25% is the max value, but sometimes feedback loops like this just go off the rails and resetting them can help.

[TheBigChill]

Originally Posted by hassmaschine

well, if you wanted to monitor the wideband loop - that would be the best way to log.

what happens if you reset adaptations? does it immediately go back to -25% trim? IIRC 25% is the max value, but sometimes feedback loops like this just go off the rails and resetting them can help.

Gotcha. I can't reset adaptations with Carly or Torque Pro; I tried and there's no feature. Disconnecting the battery doesn't clear adaptations either.

Yes, -25% LTFT is the Max value before setting a Rich code for that bank. Bank 2 is worse on my car, and throws a code before Bank 1. However, both Banks have LTFT that are excessively negative.

[hassmaschine]

yeah the adaptations are stored in permanent memory, disconnecting power won't do anything. You'll want to get something like INPA to do that but it's probably not going to permanently fix your problem.

Have you done anything like check your fuel pressure? I wouldn't think leaky injectors because it's unlikely more than one would fail. Another possibility is the MAF. One way to test it would be to disconnect the MAF signal pins and just leave the IAT pins hooked up. The car should run normally, but if your trims dial back then you know the MAF is faulty (you can't just disconnect the whole MAF because it still needs the IAT to run in the fallback mode for MAF failure).

[TheBigChill]

Originally Posted by hassmaschine

yeah the adaptations are stored in permanent memory, disconnecting power won't do anything. You'll want to get something like INPA to do that but it's probably not going to permanently fix your problem.

Have you done anything like check your fuel pressure? I wouldn't think leaky injectors because it's unlikely more than one would fail. Another possibility is the MAF. One way to test it would be to disconnect the MAF signal pins and just leave the IAT pins hooked up. The car should run normally, but if your trims dial back then you know the MAF is faulty (you can't just disconnect the whole MAF because it still needs the IAT to run in the fallback mode for MAF failure).

Yes- Fuel pressure is listed in original post. 70psi at the rail @ idle.

I'll have to try your MAF test. That's interesting, because I did disconnect the MAF and the car ran perfectly fine...no change in idle quality or anything.

[hassmaschine]

just at idle or did you drive it that way?

[TheBigChill]

Originally Posted by hassmaschine

just at idle or did you drive it that way?

Idle only

[Volasko]

It could be your MAF sensor clips. I had something similar with an annoying mixture trim CEL that wouldn't go away. I followed the tips from PhaseP using his link and replaced my connector pins on my MAF plug:

Original Thread, see page 2 for PhaseP's response link:http://www.e90post.com/forums/showthread.php?t=905209

It has been about half a year so far and it hasn't come back. You could always unplug and plug back your MAF sensor a few times to help clean the contact surfaces as a quick fix solution.

[hassmaschine]

Originally Posted by TheBigChill

Idle only

it probably won't drive well without the IAT - probably still worth a try.

[TheBigChill]

Originally Posted by Volasko

It could be your MAF sensor clips. I had something similar with an annoying mixture trim CEL that wouldn't go away. I followed the tips from PhaseP using his link and replaced my connector pins on my MAF plug:

Original Thread, see page 2 for PhaseP's response link:http://www.e90post.com/forums/showthread.php?t=905209

It has been about half a year so far and it hasn't come back. You could always unplug and plug back your MAF sensor a few times to help clean the contact surfaces as a quick fix solution.

I read Phase P's post a few days ago. It was...interesting to say the least.
Where did you guys get that connector? This seems like an unlikely culprit with my digital output MAF, but I did read and consider his post.

Thanks

[fravel]

Originally Posted by TheBigChill

I read Phase P's post a few days ago. It was...interesting to say the least.
Where did you guys get that connector? This seems like an unlikely culprit with my digital output MAF, but I did read and consider his post.

Thanks

I think I got mine from ECS Tuning. Do a parts search on RealOEM and make sure you have the right part #, should be <$10 regardless. I agree it might not help considering your digital output MAF, but I went down a rabbit hole and a half trying to fix my errors replacing the MAF, VANOS solenoids, intake manifold valves and O2 sensors with no luck. New connector did the trick - would have saved me a ton of time and money to try that first and it's so easy/cheap that if I was in your position that would be my first step.

[TheBigChill]

Originally Posted by fravel

I think I got mine from ECS Tuning. Do a parts search on RealOEM and make sure you have the right part #, should be <$10 regardless. I agree it might not help considering your digital output MAF, but I went down a rabbit hole and a half trying to fix my errors replacing the MAF, VANOS solenoids, intake manifold valves and O2 sensors with no luck. New connector did the trick - would have saved me a ton of time and money to try that first and it's so easy/cheap that if I was in your position that would be my first step.

I can't for the life of me find that connector. I see it here (part#18) https://www.realoem.com/bmw/enUS/sho...diagId=13_1165

But it's not listed in the part table below. Also couldn't find it in"miscellaneous connectors".

[fravel]

Originally Posted by TheBigChill

I can't for the life of me find that connector. I see it here (part#18) https://www.realoem.com/bmw/enUS/sho...diagId=13_1165

But it's not listed in the part table below. Also couldn't find it in"miscellaneous connectors".

Well that's a pain.

Out of curiosity, I cross-referenced the part #'s for the MAF sensor from your car to the MAF sensor in an '09 328i and they seem to be identical (13627551638). It follows that the connector plug that interfaces with the MAF would have to be identical.

Fortunately, RealOEM does show that connector for the '09 328i.

Item #17: https://www.realoem.com/bmw/enUS/sho...diagId=13_1148

Part # is: 12527516864.

ECS Tuning has it for $6.90, here

[TheBigChill]

Originally Posted by fravel

Well that's a pain.

Out of curiosity, I cross-referenced the part #'s for the MAF sensor from your car to the MAF sensor in an '09 328i and they seem to be identical (13627551638). It follows that the connector plug that interfaces with the MAF would have to be identical.

Fortunately, RealOEM does show that connector for the '09 328i.

Item #17: https://www.realoem.com/bmw/enUS/sho...diagId=13_1148

Part # is: 12527516864.

ECS Tuning has it for $6.90, here

Thanks for that. I'll give it a shot since others had success. Didn't PhaseP also attribute his success to loose harness connections at the DME for the MAF signal wires? I'm not sure which he said ultimately made the impact. Again, this all seems unlikely, but for $8....

What's most perplexing is that I don't have any drivability issues that I can notice. Everything is steady and smooth, just these annoying codes and wildly negative fuel trims.

Anyone else have any words of wisdom for this issue? I've done everything I can without buying new sensors (O2, MAF). I may just try clearing adaptations once I get my hands on a tool capable of doing so.

[fravel]

Originally Posted by TheBigChill

Thanks for that. I'll give it a shot since others had success. Didn't PhaseP also attribute his success to loose harness connections at the DME for the MAF signal wires? I'm not sure which he said ultimately made the impact. Again, this all seems unlikely, but for $8....

What's most perplexing is that I don't have any drivability issues that I can notice. Everything is steady and smooth, just these annoying codes and wildly negative fuel trims.

I could be mistaken, but I believe PhaseP's conclusion was that his MAF sensor was no longer making a good connection with the pins in the connector due to the connector getting worn out by repeatedly connecting/disconnecting it during airbox removals.

My car was the same way (except it was supposedly running rich as opposed to lean) - no noticeable issues other than the damn SES light on my dash. Started by cleaning/swapping VANOS solenoids and replacing air filter, then replaced spark plugs and coils. Eventually replaced VANOS solenoids entirely. Next was replacing MAF with aftermarket. Had indy look at it and perform smoke check - nothing. They suggested using OEM MAF, so I bought a new one of those. Still no fix. Replaced entire CCV system, while I had the intake manifold off I discovered my big DISA flap had failed, replaced both (just in case). No change. Replaced my O2 sensors, no luck. Took it to another indy shop - they were baffled. They reset adaptations and that seemed to work for a minute, but light still ended up coming back. Spent somewhere between $2.5k and $3k and 18 months trying to sort it out. Granted, my car was around the ~150k miles mark, so a lot of this could be looked at as preventative and/or routine maintenance so that's how I justified it, but a lot of it probably wasn't necessary yet.

Finally I stumbled on PhaseP's thread - haven't seen the light since I changed out that connector.

[TheBigChill]

Quick update, guys. I'd appreciate it if some INPA folks would check this out.
I've attached a few screenshots of INPA below. All were done at warm idle. I have some questions:

1) In one screen, MAF flow is 12 kg/h. In another it is 8 kg/h. Yet in another, there are 0 Volts.

2) My adaptation values for both banks, both LT and ST didn't move at all while monitoring. Yet in OBDII, they're very active (still negative).

3) Are my O2 sensors reading correctly with ~2v precat, and .70v post-cat?

4) Where am I supposed to get relevant readings for the car's different sensors?

[PhaseP]

Hello,
Yes in mine and a few fellow N52 owners with analog output MAF here the problem was caused by the connector/pins not making good tight connection. For me it has been more than a year since I replaced that connector and cleaned the pins good and I am free of them problem. (With cold weather creeping in, I now have "thermostat stuck open code" code with SES dash light, but I had replaced the thermostat last year .... another thing I have to chase now)

The digital output MAF version your engine uses is physically identical to the analog output MAF version, so the same connector would work, unless your wire harness is different. You can check your hood and compare the pictures in my thread or anywhere else if the wire harness is same or not.

Just to give you idea this link has close up photos of the analog output MAF
https://www.ecstuning.com/b-vdo-part...627520519~vdo/

And this has close up photos of your digital output MAF:
https://www.ecstuning.com/b-genuine-...f/13627551638/

You can see they are same physically, internal circuitry and the part number printed on them are different.

The MAF output is digital, but the ambient air temperature output is still same analog. If it is not making good connection on the air temperature pins it would throw off the computer also.
So for a few dollars and a very easy work it wouldn't hurt trying to replace the connector and clean up the pins good.
You can even try to disconnect and then connect and reseat it, clear the codes and see if it helps for a few days.

You can try cleaning the MAF sensor and the temperature sensor in there with a MAF cleaning spray also. Another easy and cheap thing to try. Make sure you spray inside the white plastic folding tunnel thing on the sensor, that is where the MAF hot wire is, not visible. The bead element with two lead wires visible is the temperature sensor, if it had dirt on it, it would be good to spray on it too with the MAF cleaner.

If these doesn't help you, there is possibility MAF sensor is not good.
In that case don't pay extra for the BMW branded one. VDO Continental is the OEM, you will see your original one has VDO stamp on it.

I can't help with the INPA outputs, it is too much German for me

[TheBigChill]

The first thing I did was clean the MAF, even though I never expect that to do anything really.

I bought the connector for $6 from my local BMW dealer, and I'll try that Monday. I also have a new VDO MAF that I need to try, but am waiting for my AEM DryFlow air filter to come first so that my current oiled K&N doesn't contaminate this new MAF, just to be safe.

Anyhow, regarding the INPA readings: "Spannung" means Voltage, "Luftmasse" means Mass Air, "Gemessen" means Measured, "Gruppe" means Bank (1&2), etc. It's not too hard to figure some of these out.

My point is that it clearly shows me having 0v output from the MAF, yet the flow in kg/h is present, and changes when I rev the engine. My question really is: Where should I be looking for correct readings in INPA? I'm also trying to get other owners to measure their N52 parameters so that I have a point of reference for these sensors.

[PhaseP]

Engine was running so air was flowing through it, hence not zero flow shown. The voltage being shown 0V, who knows. If you look at the first picture you have one of the O2 sensors showing zero ohm resistance. From going memory mine also shows zero ohm resistance when I check these screens, and sometime not zero ohm resistance, but I never got errors from the computer about O2 sensors.
My point these besides being in German, even in English not easy to interpret correctly.
What is apparent is your fuel trim is high, apparent from some of those % numbers displayed.
Between the two screens where it shows different air flow values, what I assume ambient temperature value is different too. Which will cause different value reported. But the values is backwards to me because hot air expanding would have less mass then cold air. I am not expert on these, and as I said it is not easy to interpret them correctly.

[PhaseP]

Also your first screen doesn't report the engine RPM. It could have been different from the third screen when you got the screen shot. Different rpm of course will give different air flow.