Rough Idle And Constant Missfire From 5th Cyl

[VXSS]

Hi all

Hoping someone can please give some ideas on this problem,

Drove my car last night turned it off after it cooled down, then went to turn it back on after a while noticed the car was running really rough and shaking and sounding like a wrx however i unplugged the coild and put it back in then it ran fine next morning on the way to work car ran fine until i got to service station turned car off and then back on and problem was there again

tested the coil packs no 5 was not getting any response when unplugged replaced that coil pack with a new one turned car back on problem still there went and baught a new spark plug installed the plug problem still there...

was advised that the o2 sensor needs to be replaced could this affect this? has anyone got any ideas ?

[VXSS]

bump!! need help asap as mechanics are gonna cost a fortune lol

have taken car to my local performance shop, coils were changed electrical test was done, compression test was done car came back with the result of full compression

they are going to test the ecu next does anyone have any info on this problem lol

[White GTS-T]

Either cylinder 5 injector or coil pack harness/loom.

[cainer33]

Either cylinder 5 injector or coil pack harness/loom.

simple troubleshooting principles apply here

-swap the coil pack from another cylinder, if it still misfired on 5th its not the coil pack, its what is driving the coil pack. You might find there is a broken wire in the loom.

the o2 sensor won't cause a car to miss on a cylinder. an o2 sensor will cause poor fuel economy, most skylines would have stuffed o2 sensors anyway, the people who drive skylines these days aren't exactly rolling in the money and won't spend it unless they have to. as i found out after i bought my one.

[Race__24]

Yeah, look at the harness. Give it a wiggle while the car is idleing

[Bluebird_TRX]

I'm currently having a similar problem - but yours could be the heat soak immediately after the engine is shut down. Mine is after the car is warmed up. My current guess is the power transistor being heat stressed and damaged. I haven't played with the coil packs wiring loom yet, but its odd that your car should be failing only after restarting it and not though normal driving bumps and vibration, so I'd rule that out - simple continuity test on that part of the looms will prove it damaged or not. Harder to test a power transistor if its cooled sufficiently to work again after its removed for testing.

Edited August 6, 2009 by Bluebird_TRX

[VXSS]

all good 500 $$ later ecu needed to be rewired as whoever installed the apexi boost controller dodged up the wires turned out half the wires were loose and pins were broken had to get it all re wired runs like a dream now thanks for anyone who got back to my post