Rough idle and stalling issue- help please!

[z4_lover]

Hi forum community,

I have a 2007 BMW Z4 E85 and have an issue where the car has a rough idle which sometimes leads to the car stalling when stopped.

I would say the issue is slightly worse after the car has warmed up.

Rough idle feels like the car is running a bit lumpy, and the idle can drop a bit lower and then this blips back but sometimes this will stall completely.

I have plugged in my fault code reader and attached the fault codes which are 29E7 and 29E8, fuel mixture adaptation.

Also, I have taken a couple of pictures in the engine bay which I think shows signs of the problem.. there appears to be an oil leak. I have read a couple of posts that this may be the idle valve. Has anyone else had this problem and replaced this part and fixed the issue?

I have had a look over the hoses and they appear to be in good condition which was the other fix mentioned. Any help is greatly appreciated

 

[z4_lover]

If it helps, the full fault codes are:

29E8 Mixture adaptation 2 (leakage air)
29E7 Fuel mixture adaptation (air leak)

 

[wonkydonkey]

Hi. Sorry to hear about your troubles. When you say you've "had a look over the hoses" and they "appear to be in good condition", can I read that to say it wasn't necessarily the most thorough inspection of the rubber hoses on the inlet side of the engine? The error codes are helpfully directing you to look for an air leak on the inlet side, so that is the best place to start. The large hose between the air box and the inlet manifold is prone to splitting, and isn't too big a job to remove so you can look at it under a good light. Any other hoses connected to the inlet manifold can also upset the mixture, so if that main intake hose is free of damage, check the rest as a starting point

 

[Capa]

As with the above, this smells like an air leak before the cylinder. Have a goooood look at the inlet pipe, and if no joy, get a smoke test done.