When the car is cold and you start it up the RPMs should go somewhere around 1800 and then drop slowly as the car heats up until RPMS goes up to normal. Around 700-800

Thats how my car used to be.

 

Now it goes up to 1800 and then drops down immidiately. Sometimes it stays up to 600 and sometimes it shuts down.

 

When it gets hot its fine.

 

What might be the problem?

I've a similar problem, when you start her in the morning the revs are erratic constantly moving up and down between 1800 and 600 then after 2 mins all ok? However, this morning she wouldnt start though did after about 5 attempts then died, started ok again but also died though on the third attempt, she fired but the revs where up and down.... Whats going on. Only recent mods was an apexi induction but thats been on a few months before this prob started though I've also fitted an ALC but cant see how this will affect the revs etc as been OK until 2 weeks ago but have noticed the throttle response can be a bit hesitant when kick down occurs.

 

All help please

Check the temp senso rconnection for dirt - It may also be failing and giving the ECU the wrong readings.

Originally posted by Bilky

Check the temp senso rconnection for dirt - It may also be failing and giving the ECU the wrong readings.

 

Cheers Bilky, had a look and pretty well corroded so quick clean and I'll find out in the morning... Noticed on Andy's site theres a few links to erratic idle etc so guess if all else fails I'll have to work through the list which includes temp sensor..

 

Shane

Originally posted by Bilky

Check the temp senso rconnection for dirt - It may also be failing and giving the ECU the wrong readings.

 

I have replaced the entire EFI harness and I also put a new Coolant tempreture sensor. Still I have same problem.

 

My problem is not erratic idle. It starts but it doesnt keep the RPS's high enough to get the car warm up. It goes immidiately down and sometimes it dies.

 

I suspect Air Regulator valve, or TPS, or MAS. But if anybody knows anything more I would like to hear.

I would suspect what used to be called on my Opel Manta as the Auxilliary Air Valve - AAV - it allows more air into the engine on cold startup bu then the ECU sends a signal to it to close when up to temp - We do have one on the Z but I cant remember the exact name for it. Someone might help out on its official name. The car would start but not run consistantly until it was warm, cutting out a lot.

IVE HAD THE SAME THING NOT AS BAD AS YOU GUY. THE REVS GO HIGH AND LOW ABOUT 3-5 TIMES AND THEN ITS FINE GOT SOME DAMP START SPRAY AND COVERED THE ENGINE BAY IN IT AND NOW IS FINE JAP CARS ARE PRONE TO COLD AND DAMP WETHER MY OLD GTI-R HAD THE SME PROPLEM WAS FINE IN THE GARAGE ALL WINTER BUT SOLD HOUSE AND NOW NO GARAGE AND HATED THE COLD

Was hoping it was just cold, tried Bilkys suggestion and a lot better this morning..

 

Cheers