View Single Post
      03-04-2012, 11:19 PM   #19
That's what she said...
bigjae1976's Avatar

Drives: 11 E90 M3 Individual
Join Date: Mar 2006
Location: Milwaukee, WI

iTrader: (13)

Garage List
2004 BMW M3  [4.50]
2011 BMW E90 M3  [5.00]
2013 BMW 328i  [5.00]
Originally Posted by M3roar View Post
Yeah, Id rather it running rich than too lean... I'm getting some boost gauges installed .... I might at that point custom make some pulleys for different levels of boost and find one that fits the bill for rich/lean ratio...
I found out that part my problem was the 4 screws which hold the compressor onto the manifold were coming loose. There is RTV which acts as a gasket. I think the RTV was basically preventing a massive vacuum leak...which my time at the track caused it to just a smoke test revealed. I had to pull the entire manifold/compressor assembly. Then clean and apply RTV to the surfaces and loctite the bolts.

What I learned is a vacuum leak could cause your car to run rich. Unmetered air causes the computer to increase the fuel trims and start dumping fuel...causing your car to run pig rich. I believe that at idle, where my car ran like crap, there would be a leak from the manifold/compressor joint. Then when you get under boost, it would seal the joint, kind of like suction. So the computer would increase the fuel trims at idle as a part of adaptation, thus, the car would run rich under boost due to no unmetered air and the joint sealing. I'm guessing because I didn't spend as much time under boost as I did under vacuum that the DME would not adapt itself. That would also explain my mix of rich and lean codes.

You can check 2 of the top'll have to pull the assembly to get the bottom bolts. Or have a triple jointed wrist. Wouldn't hurt to rule it out.

Oh yeah...hope you sell your wheels.

Sponsored by Momentum BMW #593...We Bleed BMW BLUE!