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Old 05-16-2012, 12:15 PM   #23
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Join Date: Apr 2010
Location: Murrieta, CA
Posts: 9,194
My Ride: '94 325iC & '00 323i
Originally Posted by rfbmwfan View Post
I do work in a shop, however I don't put used parts on my car. I did mention that I used aftermarket cam position sensors (no trouble the last 2 years since installed though).

Coil and injector have been swapped, all plugs look good, compression test resulted in 120 across all cylinders.

The car runs perfectly fine with no misses until warmed up to normal operating temp.

I've combed through wiring to make sure there are no tears or fraying of wires, cleaned contacts, checked fuses and relays. Checked for vacuum leaks with a smoker.

e46mango, I have the bosch plugs installed, it was an oem part number I got for them. Had them installed since last year when I did my valve cover gasket.

Not sure what happened to my original post, was on my phone.. obviously I erased the whole original post and replaced it with another lol. oops.

Anyways, next on the list is a fuel pressure test.
All of those things except swapping the coil and injector feed into global misfire symptoms, or at least multiple cylinder misfires.

I'm trying to help separate the chaff from the wheat here.

Fuel pressure low can certainly give misfire problems, but logic dictates the problems will be global, not unique to one specific cylinder. The same goes for the Cam Position Sensor, fuses, relays, etc.

Used parts are not a problem if you know they are not defective. I frequently will save something that I took off of my car to use for a spare someday, especially when the new part and the old part give the same symptom. I have a used starter on the shelf now that was replaced, and I discovered after installing the new one that the old one was merely dirty or had a missing screw -- I forget what the problem was, but I was able to fix it so it lives on the shelf waiting for a chance to be used again. I was only meaning that if you are putting in used parts of unknown integrity, then you might be chasing your tail as a result.

It is impossible from this side of the interweb to tell what is wrong with your car, but I get the feeling that you are looking at things that should have a global impact but you repeatedly report a problem that is unique to a single cylinder. It seems to me that you need a diagnostic approach that is also unique to the same cylinder. You cannot do anything to move the problem, so the issue has to be something like a frayed wire or some manner of failure of the injector firing circuit, or an internal problem with the motor.
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