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Old 10-06-2009, 11:02 PM   #1054
Rajaie
Registered User
 
Join Date: Nov 2007
Location: Raleigh, NC
Posts: 1,271
My Ride: 528i 06/00
Quote:
Originally Posted by devedean View Post
I brief history of my problem:

Approximately 6 months ago I was beginning to get engine hesitation when letting out the clutch at a stop light. I ordered your seals and replaced the VANOS seals along with changing spark plus and all valve cover gaskets. The car ran beautifully for approx. 50 miles and then started idling horribly to the point where it would almost stall and had zero power. The SES light came on and the idle seem to normalize, but it was still rough and the light remained on. Without reading the codes decided to replace both intake and exhaust CPS (OEM brand). There was no change and so I brought it to my indy mechanic where he read the P1520 code along with multiple misfires.

To rule out bad coils he replaced them all along with a redline oil change and engine flush. The codes came back immediately and the issue wasn't resolved. I went ahead and replaced the CCV calve along with all 4 hoses. I inspected the idle control valve boot as well as the intake boot while I was in there and there were no cracks evident. I also cleaned the exhaust VANOS solenoid per your recommendation to no avail.

This brings me to today: P1520 and multiple random misfires, rough idle, and hesitation when letting out the clutch at a stop light (more pronounced after the car is hot after driving for a while).
Maybe you didn't install the sparkplugs correctly. When you screw them in you will first get resistance. You should then continue to tighten them for ~1/3 turn till they fully tighten. If you didn't fully tighten they will come loose and cause your symptoms after maybe 50 miles.

Take out and clean the idle control valve.

You might have a clogged fuel filter.

Your pre-cat O2 sensors are due for replacement. They have a lifespan of 100k miles. They usually fail by over enriching the air/fuel mix so it wouldn't cause your symptoms. But you will get worsening gas mileage.

Disconnect the MAF electrical connector. If the problems completely resolve then it might be the MAF. Disconnecting the MAF will cause the DME to enrich the air/fuel mix and this will hide a vacuum leak. So you have to be careful with this test.

Were the CPS sensors new? Did you get them from a BMW dealership? Do they have a BMW logo on them?
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