Rb26 - Rough Idle And Stalling On A Warm Day

[Jenius]

I've been reading through a bunch of threads with similar issues yet nothing that directly relates so far.

If have a BNR32 GT-R and it's been a long cold winter here in Melbourne and the car felt like it was running fine and smooth the whole time. As there's been few warm days recently its been causing the car the run with rough idles and almost stalling at times. It will only happen if its on a warm day of more than 20 degrees.

I've also noticed that the engine check light will flash at times and then be ok again but other than that car will boost ok and give off consistent power.

So far I've read that it could be one of the vacuum lines in the plenum or the timing itself. My guess is that it could be the AFM's or sparkplugs. I am running stock AFM's with an ARC Airbox.

I also took it to be Dyno tested to see if the issue could be replicated but they found nothing aside from it running slightly hotter than usual after load. I am running an aftermarket radiator as well. However it was fairly cold day so it may have been easily spotted.

Was wondering if anyone else has had experiences with this and any suggestions would be appreciated!

[Moodles2]

Anytime the engine light flashes, the ECU will store that error code until you either clear it via CONSULT or disconnect the battery. Either read the error flashes from the ECU, or get yourself a CONSULT cable or one of these: http://ecutalk.com/consultlcd.aspx and grab that error code.

When were the spark plugs last changed, and what type are they (copper, platinum, iridium etc).

Can you hear any hissing (vacuum) in the enginebay while idling?

If you spray something with alcohol (wd40, brake cleaner, aerostart etc) around the intake manifold, ITB's, vacuum hoses does the RPM (engine changing note) temporarily rise?

Things that go wrong when hot but work fine cold, generally don't rule out the coilpack ignitor or the crank angle sensor. Until you get that error code, it's all guesswork and you might even be on the wrong track.

[Jenius]

Thanks for the suggestions there. I'll go down the CONSULT route for now and see what its telling me first.

Sparkplugs I'm running are just NGK Platinums but I don't remember the gapping of it. But they are almost 2 years old now so may need to pull them and check. I changed the coilpacks a few years ago to Splitfires so I somehow doubt that would be it. :-/

Can't hear any hissing or vacuum leaks so far but will check further there but I haven't tried the WD40 with the intake manifold yet but if RPM rises for a bit is that a good sign?

[Moodles2]

If RPM rises it's a bad sign, means the alcohol is leaking into the air intake and the engine is burning it

[AngryRB]

thats the sort of thing that was happening when i had a intake manifold leak, was fine til it was at operating temp, got worse every day

the leak makes it run lean and thats what makes it rough and stall, but the opposite happened on full throttle, id get some big black clouds out the back, fill up half the street ..also seeing boost but not feeling the power for a few seconds cause it was blowing out the manifold... any of that happening?

Edited September 19, 2012 by SliverS2

[Jenius]

Manifold leak I'm still investigating as it seems to run ok 90% of the time.

Since its been getting warmer recently I've noticed it happening more often and I can sort of replicate it if I deliberately try to stall it where it will take over and try to keep the revs up. It will then start 'hunting' for up to 10-15 minutes afterwards.

Cruising along at constant speed it will feel erratic during that time.

I'm starting to count on the AFM's needing replacement in this case.