Uneven idle RPM

[ViR2]

On a cold car my rpm's at idle are 1400, when it hot's up they drop to 900 @ idle. But sometimes after boosting or just driving in city for a longer time they just wont drop to 900 and stay up to 1400rpm's @ idle (like on cold engine). Does any1 know where to start looking for a problem? Vacuum seems to be fine and no code's.

Engine is base stock + hks ssqv and fully rebuilt 2000km ago

 

[mkiiSupraMan18]

Is your throttle linkage letting the TB close all the way? That's the easiest to check, just see if you can push it closed any further.

I'm 100% what does what with these engines electronically, so I can't help you there. :icon_conf

 

[ViR2]

yup it's closing all the way. BTW when i reset ecu idle sits @ 650 (hot engine, at idle) then after some driving it settles at 900 and then it starts all over again.
Any more sugesstions?

 

[johnathan1]

Any codes? I'm thinking either the TPS, or the ECU temp. sensor, and/or wiring to them.

 

[Jayhall]

Check your codes, my AFM went and my car was all wacky at idle

 

[mkiiSupraMan18]

Would a leaking BOV do that?

 

[trydrew]

Would a leaking BOV do that?

Shouldn't.

 

[Big Wang Bandit]

My car has a simmilar dielemma. Im idling at 1000RPM... Im gonna check my throttle linkage like now.....

 

[mkiiSupraMan18]

^ lol It happened on mine because it was too short... it was only an idea and an easy check.

 

[ViR2]

mine seems to be okey, but why the hell does it idle some times at 900rpm's and some times at 1400rpm's (like on cold engine)?

 

[koulee]

mine seems to be okey, but why the hell does it idle some times at 900rpm's and some times at 1400rpm's (like on cold engine)?

If its a dead cold start, thats what the engine will do: raise the revs up for a short period of time. But it should drop back down to 650-700 when hot.

 

[boost fiend]

how is the cold start injector? tb spring still ok?

 

[ViR2]

koulee: I was talking about hot engine, when it's cold and it warms up it act's just like it should, but after driving it starts to go crazy

Yep TB springs are new. How to check cold start injector?

 

[supra90mkiii]

fauly/bad coolant temp sensor?

it could be messing up and telling the ecm that the engine is cold... causing it to go into "cold engine mode"....eh? ...just a thought.

 

[ViR2]

I was thinking about it earlyer so i've replaced it today, but still the same.
I've driven it hard for about 5miles and my idle is @ 1400again

 

[johnathan1]

Check your codes!!!!!

 

[ViR2]

no codes, after reseting ecu again my idle is sitting normal at 650, then i drove it ~2miles @ redline boosting, and yet again idle is at 1400 :icon_evil
This car and it's behavior is weird :joshers:

 

[johnathan1]

What was max boost psi? You may want to check for boost leaks, check your TPS, and your ISC, and all related wiring, and I bet you'll find the problem.

 

[ViR2]

Boost, well, i dont know it in PSI's (i have euro supra) but its stock.
What procedures should i check TPS and ISC by? Or just the wiring?

 

[suprashy]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&Page=100