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.. once in awhile (I think usually when engine cold) the car would start and be missing at least one cylinder. In at least one case I shut off and restarted fine.
..separate but probably related symptom was only at like 3K rev under load (like going up a steep hill), engine would stumble/misfire. At first would stop if I backed off the pedal and no codes thrown, but 5-10K miles later would consistently light CEL but code reader would still show "pass".
Problem went away when I put in a new CPS and a swapped in a vanos solenoid. Don't know which solved it since I did them together, but I think it was the CPS. My guess is when the CPS gets old the pulse signal is weak and at higher rev (ie pulse frequency) it's harder for the ECU to count the pulses.
Car now has lots more power. I had issues with CPS before on another BMW. I recommend it be replaced every 100K miles even if no cel.
..separate but probably related symptom was only at like 3K rev under load (like going up a steep hill), engine would stumble/misfire. At first would stop if I backed off the pedal and no codes thrown, but 5-10K miles later would consistently light CEL but code reader would still show "pass".
Problem went away when I put in a new CPS and a swapped in a vanos solenoid. Don't know which solved it since I did them together, but I think it was the CPS. My guess is when the CPS gets old the pulse signal is weak and at higher rev (ie pulse frequency) it's harder for the ECU to count the pulses.
Car now has lots more power. I had issues with CPS before on another BMW. I recommend it be replaced every 100K miles even if no cel.
