what would keep cylinder #1 from firing?
car is currenty running on 3 cyl at idle, from what i can tell it feels fine under boost or part throttle. It all started after a nasty backfire under launch with the 2 step.
I have swapped the injectors ,changed the plugs(plug #1 is black and dry), swap the coil packs and reinstalled my stock flashed ecu (i am running aem) i have o2 sensor codes and a p0301(misfire #1). Last night i checked the compression and #1 is down 15psi
170 185 185 185. After swaping the injectors i pull the harness off the #1 cylinder car runs the same (three cylinder), if i do the same to #2,3,4 cylinder car fumbles and dies out.
any clues? my next step is to tear down the head to check to see if i have a burnt valve or damage piston.


ps car doesn't smoke or show any signs of weak motor
thanks

 

Please reload your firmware and calibration and see if it goes away before you tear anything apart.

Sean

 

Had a similar problem with my supercharged Integra. Vibrates at idle but fine driving normally.
#1 cyl----90psi
#234----130psi
4 revolution of the motor WOT test on compression.
Added oil in #1 and psi shot up to 140---rings were shot.

 

sean,
I will try that tonight, not sure if it will fix the problem since i have swaped the aem to stock flashed ecu and had the same problem.

thanks for the insight

 

Well in that case you may want to start doing compression and leakdown tests on the engine.

Sean

 

compression is 170 185 185 185

 

Do a leakdown test.

Sean

 

DID a leakdown test today and i am only losing 5% from 100psi.

what next?
QUOTE=Sean@Iveytune;4081721]Do a leakdown test.

Sean[/QUOTE]

 

Wow, strange one. Take off the valve cover and see if the #1 valve train looks in place...a really badly bent valve stem can stay closed and seal so compression numbers and leakdown look decent but obviously cylinder will not function if either intake or exhaust valve fails to open.

 

will give that a shot