Cant Work Out Why My Car Has A Low Idle And Stalling On Hot Starts

[Gerg_R31]

cold days it is fine, but if i drive somewhere say to the shops, it reaches operating temperature then come back 5 minutes later it acts up, or just on hot days.

ill start it, it will idle low when i accelerate it will sound like its running on 3 cylinders and pisses out black smoke, if its doing this in stop go traffic it will run like shit stall & piss out black smoke

i know the black smoke means un burnt fuel

anyways the cars history

r31 skyline, rb30e,

2 years ago reconditioned the head at my work shop, had cam reground, raised to compression from 9:1 to 9.6:1, stock computer

year ago converted it to manual,

since the manual conversion its had issues, replaced start motor, alternator, all new belts, 2 afm (1 new), new bosch coil, new thermostat, radiator cap, radiator hoses, 2 dizzies (1 was out of a vl and was told the wiring is slightly different to the nissan)

every 3 months/5000kms i change oil and filter, every 6 months 10,000kms i change oil, oil filter, spark plug leads and spark plugs, every year 20,000kms new fuel filter, air filter etc

i have changed just about every sensor, bought all genuine, sprayed 2 cans of carby/ throttle body cleaner, AAC is clean and carbon free, had injectors cleaned

i replaced the reground cam with a standard cam

ive had numerous mechanics look at it and its either not been an issue when they had it, or they couldnt find anything

im starting to think maybe a cylinder or to has excesive clearance or the rings are on their way out, but it doesnt use any oil

any1 got ideas?

[Gerg_R31]

no one has any ideas?

[Moodles2]

Not familiar at all with RB30s so this might not be any help at all to you, dodgy ignitor modules malfunction when they get hot, though usually it results in misfiring, might be worth also finding a better ground for the ignitors ground wire.

[blind_elk]

For the RB20 (yes, I know you have a 30E, but I don't have the manual for a 30E), difficult hot starts can be caused by faulty temp sensor, or fuel pressure.

Since you've replaced the engine temp sensor, maybe try removing the vacuum line from the FPR to get more fuel pressure.

And if the engine can't spin fast enough, due to faulty / dying battery.

[Gerg_R31]

the ignitor module, being dizzy set up im sure u mean the single coil, which was replaced

fuel pressure regulator... might give that ago will keep you all updated

[blind_elk]

I'm pretty sure they have an ignitor module - little black box on the side of the dizzy body.

[Gerg_R31]

I'm pretty sure they have an ignitor module - little black box on the side of the dizzy body.

solved,

my thermo fan that came with the car didnt work so i wired up my own thermo fan, found out the sensor that tells the computer that the thermo fan needs to come on was confusing the computer, ust so i just disconnected that switch

thanks everyone for their help and suggestions