Car in question is a 2/91 318iS with (duh) a M42.
Here are my symptoms:
The only code that comes up with the stomp test is 1216 (TPS)
It does it worst and most consistently at cold, but often when warm it will do it much "softer" so it is much more tolerable and less prone to bucking.
Off idle if you apply the throttle quickly it will start hesitation, it feels like its only hitting on 2 cylinders and there is a distinct miss sound. If you ease up on the pedal it does seem to do it less. Once the engine reaches the 1500-2000rpm range it completely stops the hesitation and will eagerly rip to redline gear after gear.
If I take off from a rolling start in 1st gear at 800rpm or so (basically idling forward) and just wham WOT it will stutter all the way to redline without letting up. If I ease up just a bit then pound it back down it will stop the BS and pull cleanly. I was able to get it to do this consistently.
It will still stutter to redline if I give it too much throttle (but not WOT) off the roll, and hold it there.
Outside of that RPM range off idle the problem is not present.
The engine does hold a reasonably smooth steady idle, with or without the AC on.
So far I troubleshooted by:
Removed the spark plugs. They looks like fairly new Bosch +2's
Removed the crank & cam position sensors and cleaned the grease cakes off them.
I've already checked all the hoses for vacuum leaks, I'm 110% sure there are no vacuum leaks.
Swapped in a known good ECU
Swapped in a known good AFM
Swapped in a known good coil pack
Installed a new TPS.
Verified continuity of the TPS wiring connector to ECU with a meter, and by eye the whole way... 0.0 OHM and clean wire.
Checked ignition wires in the dark for obvious arching.. none observed.
pulled each plug wire off the plug with the engine running and listened, all produce a nice spark while hovered above the plug. Each when pulled fully away produces the normal dropped cylinder running.
Metered out CPS's
Crank sensor was 610ohms.
Cam sensor was 1480ohms.
Installed new fuel filter
Installed new air filter
This one has me pretty stumped and I really don't want to keep throwing money at what is at best a guess... hoping to get lucky. Open to any and all suggestions!
Here are my symptoms:
The only code that comes up with the stomp test is 1216 (TPS)
It does it worst and most consistently at cold, but often when warm it will do it much "softer" so it is much more tolerable and less prone to bucking.
Off idle if you apply the throttle quickly it will start hesitation, it feels like its only hitting on 2 cylinders and there is a distinct miss sound. If you ease up on the pedal it does seem to do it less. Once the engine reaches the 1500-2000rpm range it completely stops the hesitation and will eagerly rip to redline gear after gear.
If I take off from a rolling start in 1st gear at 800rpm or so (basically idling forward) and just wham WOT it will stutter all the way to redline without letting up. If I ease up just a bit then pound it back down it will stop the BS and pull cleanly. I was able to get it to do this consistently.
It will still stutter to redline if I give it too much throttle (but not WOT) off the roll, and hold it there.
Outside of that RPM range off idle the problem is not present.
The engine does hold a reasonably smooth steady idle, with or without the AC on.
So far I troubleshooted by:
Removed the spark plugs. They looks like fairly new Bosch +2's
Removed the crank & cam position sensors and cleaned the grease cakes off them.
I've already checked all the hoses for vacuum leaks, I'm 110% sure there are no vacuum leaks.
Swapped in a known good ECU
Swapped in a known good AFM
Swapped in a known good coil pack
Installed a new TPS.
Verified continuity of the TPS wiring connector to ECU with a meter, and by eye the whole way... 0.0 OHM and clean wire.
Checked ignition wires in the dark for obvious arching.. none observed.
pulled each plug wire off the plug with the engine running and listened, all produce a nice spark while hovered above the plug. Each when pulled fully away produces the normal dropped cylinder running.
Metered out CPS's
Crank sensor was 610ohms.
Cam sensor was 1480ohms.
Installed new fuel filter
Installed new air filter
This one has me pretty stumped and I really don't want to keep throwing money at what is at best a guess... hoping to get lucky. Open to any and all suggestions!
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