Thread: Engine Problem
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Old 11-30-2011, 02:36 PM   #33
Registered User
Join Date: Mar 2010
Location: Virginia
Posts: 15
My Ride: 03 325i
Does it idle rough at all, especially on cold starts? You may have a vacuum leak. I went through this recently for about a month.

I would pull the codes and have random multiple misfires, misfire on startup. Then I would clear the codes and it would come back with low voltage on the MAF, misfires, lean system. So mine started out as if it were coils going bad, but in the end I had a vacuum leak.

Get a lower intake boot (known for tearing) I got mine from a local dealer for about $19. I couldn't wait for an order because this is my daily driver. Pick up some MAF cleaner and TB cleaner. Clean the MAF and remove the TB and ICV and clean those. While you're in there, check for any brittle or dry rotted vacuum hoses. Once you have it taken apart, check the hose from the oil separator (CCV) to the dipstick tube. Mine was melted in half from the heat. That's why mine was getting worse overtime. It started small but eventually melted into two pieces. Since it's my DD, I didn't have time to wait for an oil separator kit to do the whole job so now I have to do it again LOL. Just to save a bit of trouble, if it is that hose, its 7/16 and needs to be cut to 10-1/4" length.
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