I have an intermittent start-up problem with my 2001 BMW Z-3, 3.0: cylinder 1 misfires on start-up for a few seconds or up to a few minutes under certain conditions.
The misfire conditions are consistent:
A) OBDII code P0313 (misfire detected with low fuel) or code PO1343 (cylinder 1 misfire with fuel cutoff). Both OBDII codes equate to BMW fault code 238.
B) after winter storage it misfires on start–up for 5-10 minutes (I’ve always added a fuel stabilizer before winter storage);
C) after a spike in humidity it misfires on start-up for a few seconds or up to a minute after a rain storm or;
D) If I don’t run the car for a 3-5 days (always stored in a garage) it misfires for a few seconds (just long enough to turn on the “check engine” light).
Otherwise, the car runs flawlessly –plenty of power – smooth as silk - no hesitation, but with the bloody check engine light on 50% of the time.
In lieu of black tape over the check engine indicator, I’ve taken the car alternately to both Minneapolis BMW dealers over the years (once if not twice a year), but the intermittent nature of the misfire and the fact that I store the car 5 months the a year has made it difficult to pin down the exact “root cause” of the problem. The dealership mechanics have swapped and/or replaced the cylinder 1 fuel injector, spark plug, cylinder coil and cable, kept it overnight and for days. The last dealership diagnosis was a defective cylinder 1 exhaust valve that could only be fixed with a $2800 valve job!
Yes, that’s right, pull the head and do a complete valve job - on all six cylinders. What am I missing here? What about the infamous BMW VANOS valve control system?
Thanks for your help and insights,
Tom in Minneapolis