86 NA. Dies, but idles perfectly with AFM unplugged
08-06-2010, 12:54 AM
#1
Race Director
Thread Starter
86 NA. Dies, but idles perfectly with AFM unplugged
After a 6 year hiatus, my mom started to DD her 944 again. Everything was going nicely until today when apparently the car started to hesitate, then not rev above 3K, then just start and die.
I drove over, saw the J-boot popped off of the AFM, figured that was it and no change. While messing with stuff, I noticed if the AFM was unplugged, the car would idle perfectly, but die as soon as I plugged it in.
I tried to make sure the door was moving freely and then I removed the cover from the AFM and cleaned up the track, but it still dies when it's plugged in.
Does this sound like a bad AFM? FWIW, it was also raining today and the passenger side floor got wet at some point - anyone ever damage the DME like this?
I drove over, saw the J-boot popped off of the AFM, figured that was it and no change. While messing with stuff, I noticed if the AFM was unplugged, the car would idle perfectly, but die as soon as I plugged it in.
I tried to make sure the door was moving freely and then I removed the cover from the AFM and cleaned up the track, but it still dies when it's plugged in.
Does this sound like a bad AFM? FWIW, it was also raining today and the passenger side floor got wet at some point - anyone ever damage the DME like this?
08-06-2010, 08:15 AM
#2
Race Director
Did you try giving the AFM a decent whack or tap with your hand? I know that sounds silly but I have done that in a pinch when all else has failed and its worked, believe it or not............
08-06-2010, 08:35 AM
#3
Rennlist Member
So, it idles fine with the AFM unplugged, but not with it plugged in? That sounds pretty odd.
My guess is you have some other air leak (especially since the j-boot was off) - with the AFM unplugged (or failed) the DME should default to a certain air-fuel ratio... Which, accidentally, is providing the right ratio for a good idle. When you plug the AFM in, the DME detects it and changes the fuel ratio - but now it's not a good ratio for the amount of air going in, so the engine dies.
Make sense?
My guess is you have some other air leak (especially since the j-boot was off) - with the AFM unplugged (or failed) the DME should default to a certain air-fuel ratio... Which, accidentally, is providing the right ratio for a good idle. When you plug the AFM in, the DME detects it and changes the fuel ratio - but now it's not a good ratio for the amount of air going in, so the engine dies.
Make sense?
