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Old 11-13-2012, 01:56 PM   #8
Registered User
Join Date: Nov 2012
Location: Waukegan, Illinois
Posts: 15
My Ride: '01 330xi
Originally Posted by jfoj View Post
Assume you have read the first link below in my signature?

Are you sure the CCV lower oil return hose is good? If you have a cold weather hose, with the insulation, it will many times hide the bad hose. If the hose is covered with oil, it is bad.

You may have other bad CCV hoses as well.

MAF cleaner only works for MAF's that have oil on them. You could have a bad MAF or a non-OEM MAF that is under reporting the air flow. Usually a bad MAF will trigger the CEL at a cruise and not idle.

Even though you changed the valve cover gasket, you could have a cracked valve cover. Lots of small vacuum hoses under the rear of the intake that can get disconnected or go bad.

You have to figure out if you have a crankcase air leak, a vacuum leak in the intake path or a bad MAF under reporting the airflow.

Do you have the ability to read the MAF Grams/sec airflow and fuel trims? This may help, otherwise a smoke test may be needed.

Smoke test both the intake path and the crankcase.
Hey, jfoj

Yeah i've read your first 2 links (very useful info) which is why I changed my fuel pump which was the original with 163k miles.
I've physically grabbed the oil return hose and checked both sides of the connections and they felt fine, no oil on them as well.

I also read on another thread that by blowing down the oil dipstick you could check some CCV hose if the oil bubbled? Regardless I did this and my oil did indeed bubble. About an hour ago I went back in to clean up my ICV which I cleaned about ~a month ago and it was stuck and not freely moving until I sprayed it down. I also changed the vacuum hose from the 'F' connector that goes to the fuel filter.

With regards to the MAF, about 2 months ago I ordered a non-oem MAF (big mistake!) when I was initially getting the codes, the non-oem MAF caused my car to stall out at a light and idle horribly, I put my old MAF back in ASAP and the car ran fine.

I also had the car smoked when the codes first came up and the culprit were the 2 intake boots- which got changed and some hoses.

I dont have anything to measure the fuel trims, but im assuming its throwing more gas then it needs considering 3 days ago when the light came off, the car was getting ~20.6 MPG, yesterday when the light came on it was dropping and when I checked it was at 19.4 MPG, same driving style and route.

Last edited by E46Zone; 11-13-2012 at 02:23 PM. Reason: spellcheck
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