Missfire On Cold Mornings When Car Is Warming Up

[UNR33L]

My friends car missfires on cold starts when warming up, but once warm it only does it every now and then, also when turning left and putting foot down a little bit it will sometimes missfire as well. Engine is a RB25DE.

When cold start in cold mornings say foot is down 5% it wont do it but when at 25-75% it will just stutter, also idle at lights when stopped makes his car sound like it has lumpy cams and vibrates a bit? oh and the car is just generally slow when under these effects.

Any ideas? I thought it could just be spark plugs but not sure. (could be condensation in mornings or something?)

Thanks in advanced.

[SLEEPR85]

Checked coilpacks? Do a search on missfire and more often than not coilpacks are the problem. Before i put my splitfires in i had the same problem, idled rough as f@#k - sounded like a rotary. Coilpacks fixed this issue for me.

[UNR33L]

ah ok will do cheers mate, proably not AFM related because its not all the time?

[R3N3]

check the spark plugs as well, my 25det was miss-firing a bit, i changed the plugs and re-gapped them to .8 and it was all good, only cost me $12. also, if you have a series 2, check the coil packs, they are prone to forming hairline cracks which the spark jumps from. if they are bung, try repairing them before buying new ones, theres some good threads on how to repair them on here.

[RANDY]

Agreed to coilpacks as a suspect.

Mine did very much the same thing, but since I put splitfires in it's been perfect. 1.1mm gapping on iridiums for the last 3 years and it doesn't miss a beat.

Possibly even the knockoff red and yellow "jacket" coilpacks would be fine too?

[fib]

I have the exact same problem with misfires on cold start. Car idles a bit rough also when it's cold but on warmer mornings this does not happen.

I have new splitfire coilpacks and new platinum plugs and also second hand r34 gtr AFMs, this has reduced the misfires but I can still feel it. Like others once the car warms up it's fine.

Might be a plug gap problem? If so then should I get some copper NGKs and get them gapped to 0.8mm?

[R3N3]

I have the exact same problem with misfires on cold start. Car idles a bit rough also when it's cold but on warmer mornings this does not happen.

I have new splitfire coilpacks and new platinum plugs and also second hand r34 gtr AFMs, this has reduced the misfires but I can still feel it. Like others once the car warms up it's fine.

Might be a plug gap problem? If so then should I get some copper NGKs and get them gapped to 0.8mm?

yeah id start with the plug gap, its easy to do yourself, and will take under an hour. then work from there