idle bounce on start up and when I depower

[Jack m]

Hey guys. It says it in the heading. I've got a 91 3vze engine and when I start it up it has trouble starting sometimes and other times it starts fine. But once started the idle bounces between 1000rpm - 500rpm. I'm not sure if its an ecu issue or not. Keep in mind it only does this idle bounce once warm. On cold start it is fine.
Any help is greatly appreciated.
Cheers
Jack

 

[Jack m]

Can anyone help? Urgent. Some more info. When I come to a stop it idle bounces as well but not when the engine is still cold

 

[92-SR5]

Vacuum leak?

 

[Jack m]

Surly if it was a vaccum leak it would still idle bounce when cold. But when its cold it runs fine. I will check tho

 

[KidVermicious]

Surly if it was a vaccum leak it would still idle bounce when cold. But when its cold it runs fine. I will check tho

Unless your warm engine is heating up and expanding a hose.

 

[Jack m]

Yeah most likely. Il have a look tomorrow.

 

[nicnmike]

Have you checked your coolant level?

 

[Jack m]

Yeah checked that yesterday and its filled up and a good colour

 

[nicnmike]

Have you taken the throttle body off and cleaned the coolant bypass? Sometimes that will clog and make your idle surge.

 

[Jack m]

Have you taken the throttle body off and cleaned the coolant bypass? Sometimes that will clog and make your idle surge.

Yeah I have read a bit about that and how people have used seafoam to clean it out. I'm yet to take it off tho

 

[nicnmike]

Yeah I have read a bit about that and how people have used seafoam to clean it out. I'm yet to take it off tho

I forgot about the seafoam. I did that too. Not sure if it helped, but it didn't seem to hurt. I may have been the combination of all the procedures that eventually got my idle back to where it needed to be.