I am the proud owner of an 89 M3, the engine has a miss at idle as well as when the throttle is open, i've replaced cap, rotor, wires, injectors, coolant sensor,etc. Does anyone else have suggestions as to what could be the problem? It goes to Rhine West on Monday

First, I would check for a possible intake leak. If that comes up clean, then I would check the throttle position switch. Using a multimeter, check the middle and bottom pins with the throttle closed. You should see continuity at this position. Opening the trottle, you should hear the idle switch inside click and the reading should go to open. Next, check the middle and top pins on the switch. Once the throttle reaches about 70% open, the multimeter should once again show continuity as the WOT contacts engage.

My car developed basically the same symptoms about two weeks ago. I found that plug wire #3 showed to be open, and the TPS was misadjusted and the WOT contacts inside were dirty. I fixed the TPS but I will not have the new plug wires until tomorrow. Hopefully my problem will be fixed. If not, I am curious to see what resolves your issue as mine might be similar.

Thanks, ill be in touch

god, could be tons of stuff. i've been chasing a miss for a year now

i've replaced or swapped from a friends car to test:
both fuel pumps
both flywheel sensors
main relay
fuel pump relay
AFM
chip
DME
blue coolant sensor
cap
rotor
coil
wires
plugs
cleaned injectors
fixed intake leaks


i think it's gone now. i'll find out at the next track event or some dark and rainy night in BFE

im leaning towards the flywheel sensors but who knows, the ride has over 227,000 miles on that ass.