cylinders 4 and 3 wont fire

[gsx90dsm]

While i was driving it started to studder around 5000 rpms so i let off and tried it again and then it sounded like a backfire and i lost all my boost. stopped looked under the hood there was oil all over first thing i thought was i blew the head gasket then i saw that the turbo piping off the end coming from the fmic was disconnected so i reconnected and i towed it to my garage there i started it up and it was only running on 1 and 2 cylinders i changed all plugs and wires there sparking fine got a compression test all the compression is fine and the injectors are supplying fuel. Dont know what to do next.

 

[Old Mitsu Tech]

OK, you can rule out the coils as this is a waste spark system. 1and 3 are together and 2 and 4 are together. Try squirting some carb spray into the intake while the engine is idling/missing. Does it try to pick up? Is this associated with idling or full range of rpm's?
Check your injectors at the bat + side. Then hook your test light to the bat+ side and check the injector drive circuit. If you have proper compression, proper fuel/air and spark at the right time it will run. We need to eliminate all of these as possibilities. Give us a rundown of exactly what you have and don't have.

Let us know and good luck

 

[BlueTurboSpyder]

Hi. First thing I would do is check for other boost leaks that may have sprung up when the incedent happened. Also, pull your intake pipe off and check whether your compressor wheel inside your turbo spins freely. If you find and fix all boost leaks and your turbo spins freely that should fix your problem given that you alreadly checked for fuel, spark, and compression. GOOD LUCK!

 

[Talesin]

My instinct would be to check your CAS. Had a 2/3 misfire on start a while back, sounded like a popcorn popper and would die after a few seconds (if it caught 1/4 at all). Might also check to make sure your power transistor connector didn't come loose; read another thread where that was the culprit.

 

[gsx90dsm]

OK, you can rule out the coils as this is a waste spark system. 1and 3 are together and 2 and 4 are together. Try squirting some carb spray into the intake while the engine is idling/missing. Does it try to pick up? Is this associated with idling or full range of rpm's?
Check your injectors at the bat + side. Then hook your test light to the bat+ side and check the injector drive circuit. If you have proper compression, proper fuel/air and spark at the right time it will run. We need to eliminate all of these as possibilities. Give us a rundown of exactly what you have and don't have.

Let us know and good luck

It is missing at full range i have checked the injector drive circuit. I will try the carb spray tonite.

780cc injectors
JE Pistons
Eagle Rods
Supra Fuel Pump
B&M Fuel Regulator
FMIC
20g Turbo at 22lbs
Apexi Super AFC
Greddy Type S BOV
External Wastegate
2900 ACT Clutch
HKS Cam Gears

 

[gsx90dsm]

didnt get a chance to try the spray last night because of a dead battery couldnt get it jumped will get a new battery tomorrow and try it then

 

[huafist]

My vote is for CAS as well. Went through this recently with my AWD. 3 & 4 weren't firing. Replaced the CAS, and everything was fine again.

 

[Old Mitsu Tech]

The CAS does tell it when to fire. And as electronics on these are more than a couple of years old, you would be wise to include that in your list of things to look at.

I mostly see them in a no start capacity, but any thing is possible.

Good call guys.

 

[huafist]

The CAS does tell it when to fire. And as electronics on these are more than a couple of years old, you would be wise to include that in your list of things to look at.

I mostly see them in a no start capacity, but any thing is possible.

Good call guys.

When my CAS shit the bed it did exactly what the original poster is describing - cylinders 3 & 4 were as dead as Mike Meyers' career. For some reason it didn't throw a CEL either - I'm inclined to believe it was a mechanical failure in the CAS and the electronics were stil functioning normally, thus not throwing a CEL.

 

[gsx90dsm]

Just changed the cas out yesterday and she runs. thanks a lot for the help.

 

[4g63t]

Your welcome for the CAS buddy now we get to go make some money racin fools

 

[gsx90dsm]

yeah thanks a lot for that even though its starting to act up again

 

[4g63t]

How so? what is the beest doing now?

 

[gsx90dsm]

1st gear bogs down and the only way it will move is if you ride the clutch and it just grinds when you try to get it into reverse so naturally im lost