[bzuniga]

Hey everyone! I need some help so hopefully the community expertise can best guide me. So I took my e90 2008 BMW 328i 91k miles in to the shop. I was in the process of replacing spark plugs + ignition coils to address a cylinder misfire issue that kept happening. I noticed one of the spark plug wells had oil in it so I did not put in new spark plugs or ignition coils.

I took the e90 to the shop and had my local indy BMW guy replace the Valve Cover Gasket and Valve Cover since my extended warranty covered both. Day after getting my car back I noticed it was struggling with the idle when I would start the car. You could see the RPM throttle and I even took a video I have included below.

Any who, I took it in to the shop except he said it could visibly see something was wrong due to the throttling of RPM's and the physical jerking you could feel in the car and see as you observed the engine from the front. It fixes itself but I couldn't figure out what was wrong.

So finally after 3 days I have racked up 3 codes - 29E1 MIXTURE CONTROL 2, 29E0 MIXTURE CONTORL, 2D06 AIR-MASS SYSTEM

This leads me to initially think that my MAF sensor is done for. Once I looked into this more I found a thread where a guy had the same exact situation, replaced VCG and had the exact same codes and symptoms after replacing the VCG but he never followed up on his thread so nobody ever figured out what caused it. I now think I have a vacuum leak. please help

[noah.s]

Is it only on startup?
Really interested in finding a fix as well, I have the same problem. I also had the MAF code and I cleaned the MAF but I don't think it changed anything. Seems to be getting worse lately, maybe because of the cold.
Will be following this thread.

[GoRomeo]

Check for vaccumm leaks.

[bzuniga]

Originally Posted by noah.s

Is it only on startup?
Really interested in finding a fix as well, I have the same problem. I also had the MAF code and I cleaned the MAF but I don't think it changed anything. Seems to be getting worse lately, maybe because of the cold.
Will be following this thread.

Hello Noah!

I am in Southern California and this happens whether cold, warm, or hot. Other day I drove for an hour an a half, went into the vet office for 15 min to get my dog, came out and still did it. I happens no matter what conditions 100% time when I start my car. After a few seconds as you see in my video it stops throttling and stabilizes, but recently it has been stabilizing at 700-1100 RPM. Check engine light is on now. I am stumped with this one for now

[bzuniga]

Originally Posted by GoRomeo

Check for vaccumm leaks.

What do you recommend as the preferred method to check for Vacuum leaks>

[noah.s]

Originally Posted by bzuniga

Hello Noah!

I am in Southern California and this happens whether cold, warm, or hot. Other day I drove for an hour an a half, went into the vet office for 15 min to get my dog, came out and still did it. I happens no matter what conditions 100% time when I start my car. After a few seconds as you see in my video it stops throttling and stabilizes, but recently it has been stabilizing at 700-1100 RPM. Check engine light is on now. I am stumped with this one for now

Mine also does the same thing no matter the temperature or if the engine is warmed up, it just seems a little worse now that it's colder here in FL. I'm going to check for codes this weekend and maybe clean the VANOS solenoids. I'll try injector cleaner too.

Looking around I've seen people say to clean the VANOS solenoids and swap them, check/replace air filter, clean MAF sensor, and to use fuel injector cleaner.

[Volasko]

Possible issues due to your codes:

Vacuum leak - need smoke test to confirm if this is an issue
Faulty MAF sensor - Trying swapping it with a sensor you know works
Vanos solenoids - Worth pulling, cleaning it and swapping it (very easy)

All 3 codes are associated with the fuel system. Basically you are getting lean/rich codes on both exhaust banks and an inlet air volume out of spec error. A faulty MAF sensor can cause this or a vacuum leak (air entering your inlet AFTER the sensor). I suspect your O2 sensors are fine as the error is popping up on both banks.

[bzuniga]

Originally Posted by Volasko

Possible issues due to your codes:

Vacuum leak - need smoke test to confirm if this is an issue
Faulty MAF sensor - Trying swapping it with a sensor you know works
Vanos solenoids - Worth pulling, cleaning it and swapping it (very easy)

All 3 codes are associated with the fuel system. Basically you are getting lean/rich codes on both exhaust banks and an inlet air volume out of spec error. A faulty MAF sensor can cause this or a vacuum leak (air entering your inlet AFTER the sensor). I suspect your O2 sensors are fine as the error is popping up on both banks.

Very insightful feedback Volasko!
Given that this issue appeared immediately after having the valve cover gasket and valve cover replaced, I should look into the smoke test first right? I figure a leak is probably the most plausible if that's the case. I purchased a MAF sensor, OEM, which should be here this week or next.

[noah.s]

I cleaned and swapped my VANOS solenoids when I replaced my tensioner and idler pulley and my rough idle seems to have gone away.
I pulled them and sprayed them good with MAF cleaner, cleaned them with air, then MAF cleaner again. Then I swapped them and put it all together. Be very careful not to drop the bolts! I dropped one and it ended up in a small crevice on the underpan and too my forever to find it.

You should definitely give it a try. It's quick, easy, and free

[kolhozbrothers]

OP, did you ever figure out the problem?
I am getting the same three codes, and can't find a solution.

[BennettBucsFan]

After I changed my VCG I was getting those codes so I replaced the MAF sensor with an aftermarket one from Amazon and was still getting MAF codes sporadically. In my case I didn't have the Valvetronic motor on tight enough initially so it was letting unmetered air in that way after I got that tightened up the codes went away for a while but would come back fairly often. It took me a few months before I ran across a thread mentioning aftermarket MAF's sensors can be problematic so I popped my original MAF sensor in and have not seen fuel mixture codes sense, that was about 30K miles ago.

[BennettBucsFan]

To piggyback off my last post, make sure the MAF on the vehicle is OEM. That would be my prime suspect. Secondly I'd make sure all the bolts are torqued properly around the VCG. I'd also look at the valvetronic, and eccentric shaft position sensor gasket. I have a 2011 with an N52 so not sure if yours is the same but there is a little plastic nipple near the back of the VCG that should have a little plastic cap on it as well. I'm not sure but if that cap is gone that may cause some vacuum issues.

[chahal468]

Originally Posted by bzuniga

Hey everyone! I need some help so hopefully the community expertise can best guide me. So I took my e90 2008 BMW 328i 91k miles in to the shop. I was in the process of replacing spark plugs + ignition coils to address a cylinder misfire issue that kept happening. I noticed one of the spark plug wells had oil in it so I did not put in new spark plugs or ignition coils.

I took the e90 to the shop and had my local indy BMW guy replace the Valve Cover Gasket and Valve Cover since my extended warranty covered both. Day after getting my car back I noticed it was struggling with the idle when I would start the car. You could see the RPM throttle and I even took a video I have included below.

Any who, I took it in to the shop except he said it could visibly see something was wrong due to the throttling of RPM's and the physical jerking you could feel in the car and see as you observed the engine from the front. It fixes itself but I couldn't figure out what was wrong.

So finally after 3 days I have racked up 3 codes - 29E1 MIXTURE CONTROL 2, 29E0 MIXTURE CONTORL, 2D06 AIR-MASS SYSTEM

This leads me to initially think that my MAF sensor is done for. Once I looked into this more I found a thread where a guy had the same exact situation, replaced VCG and had the exact same codes and symptoms after replacing the VCG but he never followed up on his thread so nobody ever figured out what caused it. I now think I have a vacuum leak. please help

How you fixed this problem ? I'm having the same 3 codes.