lq4 spark knock/missfire at idle
#11
I've been fighting a similar issue for a while but mine misfires only on a light load, right before lockup. Engine light flashes, random misfire code and no lockup. Can't trace it down.
#13
TECH Enthusiast
iTrader: (5)
My opinion, given that I had the same issue for quite a while until I had someone really take time with it - its in the tune. Need to step up the timing just a tick when the throttle is getting feathered. I had my issue at 50-55mph when I just barely applied the throttle - couldn't get it to go away with plugs, vacuum checks, fuel addatives...Alvin @ PCM of NC solved it. Runs like a beast...
#14
changed the pcv and seem to solve the idle problem for the most part. the missfires dont seem to be reading at idle anymore. did my tank of 93 an 89 and its still pulling timing. im gonna plug in my stock pcm and see if it still does
#19
TECH Resident
Have you checked your coils? I had one that was intermittently missing. It would cause rough idle and part throttle problems but WOT was fine. I used an infrared temp gun on the exhaust primaries and found one a lot lower temp then the rest. That was the bad one. Been fine now for 3 years.