The engine: K20 A2.
Symptom: misfire at idle and low rpm.
Compression: #1-150, #2- 185, #3-180, #4-185.
Leak-down on all cylinders is 0-1%.
Car has Skunk cams.
Cam timing is verified correct.
Valve adjustment checked.
Spark plugs and coils were changed-did not correct the problem.
Injectors swapped out-did not correct the problem.
Engine management : K Pro.
(The problem was found after much head scratching)


Time for the gurus to strut their diagnostic acumen. Winner gets a cookie

 

iacv.

something is adding fuel when you don't need it.

Are you using the 02 to correct fuel? if you are using the 02 signal, you might have a problem with the reading.

Try disabling your IACV in KPRO, to see if that helps.

THe big problem is that the IACV doesn't add enough fuel to cause your AF ratio to be out of wack on the dyno, but you will have those backfires.


You could always just try to replace it with a known good one.

 

sssssooooooo........

What was it? Its hard to diagnose a misfire via HT.

 

Forgot all about this one. Someone assembled the head incorrectly and #1 cylinder was locked in VTEC all of the time.

 

wow how did u end up catching that?

 

Hence the 35psi compression difference between cyl #1 and 2-4. Yet the leakdown wouldnt show anything because the cam is on the base circle. That didnt look right to me when i glanced through the symptoms. I can now resume my normal sleeping pattern.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hella_JDM &raquo;</TD></TR><TR><TD CLASS="quote">wow how did u end up catching that?</TD></TR></TABLE>
Luck-something just clicked in my head.

 

wow never heard of that before, I would have guessed IACV since I had that problem when I first did my swap, it would bog and lean wayy out but fixed itself after an hour of driving on the highway