ok i am having problems with my car missing on cylinders 3 and 4.......it will miss solid for five min straight then stop missing.........i can two or three days before it will do it again.......i have swaped the coils, changed plugs, took the head off and had a valve job with new springs(gm said that was the problem was valve springs), i cleaned out the fuel rail when i had it off incase of water.......i just dont know what can make this car miss on only two cylinders intermittantly like this.....any one got a clue.....just to let you know my mods are byt tuned, zzp intercooler, hahn cai, hahn full exhaust, dejon ic piping, gms1 sensors, synapse blow off, cm stage 4 clutch....i dont think it could be a sensor cause its cylinder specific....compression is also good.......help

 

Plug wires?

 

Are you catted?

 

no i am not catted..........it has nothing to do with ignition either because when the car is missing i have checked the spark and it has always been firing a spark tester

 

Fuel or spark. If it's not ignition, maybe it's injectors?

 

There are no plug wires.

 

There are still connectors between the plugs and the coils.

 

Try moving the 2 injectors and see if the problem follows.

 

the car only really misses at idle or nutral reving but when i but a load on it like start moving it stops missing........this makes me confused cuz i have never had a bad injector do that to me......expecailly since both cylinders started doing this at exactly the same time, i dont think its that.....odds of them both going intermittantly at the same time is very unlikely.......i am starting to think its my computer

 

sounds like a bad coil but you said you swaped it out?? I would try this again...and maybe new plugs....how about gettin a log of it I bet BYT might beable to help u out

 

already changed plugs....byt said he thought it could be a o2 sensor but i dont think it would intermitently make only 2 cylinders miss like its doing

 

Did u move the injectors?

 

no not yet..........it is my dd and i need a week off to be able to pull off the intake to swap around the injectors