Weird 4age idle problem

[Otaku]

My Smallport 4age has just started doing the weirdest thing.
Started up the car last night, and it started to idle at 2,500rpm usually it only idles at 2000rpm when its cold. After I drove down the street for abit the revs started to go up and down, up and down, up and down, either when I hold the clutch down or when its in neutral.
After the engine warms up it goes back to normal and idles just below 1000rpm as it use it.
Any suggestions?

[LeeRoy]

Dude, youve either got a rooted coolant temp sensor or your running low on coolant. Both will cause the engine to do the funny idle as water will splsh on it if its low and give it a bouncy temp reading and the engine thinks its cold so bumps the idle then water hits it and it drops. If the sensors rooted it will give a false reading and do the same. Check both and all the best.

- LeeRoy

[3sgte]

It sounds like you are a bit low on coolant.

As the engine warms, the idle speed increases. Idle fuel cut occurs.
Eventually warm coolant gets to where it should be going and causes the idle speed to drop via the idle control valve.

If you are on the throttle, the idle contact in the TPS opens, causing the cycle (of fuel cut) to stop.

First check is coolant level/leaks.
Second might be idle speed/control.

[Otaku]

Yeah, just checked seem to be abit low on coolant, will change it tommorow, see how I go.

[wth03]

if not check the throttle bodies return spring
sometime the spring is being old which lead to loss the tension of it
and it counldn't close the throttle perporbly
then the ECU will try to corect the idle by itself
so it happens to idle goes up and down

[GTI-TRD]

hmmm my mate has the exactly the same problem.

I though it was like a trailg-throttle issue too, but that doesnt explain why its only when the car is cold. My other thought was a cold start injector issue.

I will tell him to check coolant level& let you know how I get on too.

cheers for info guysl id + ve rep if I could

[skaney]

Ive got a similar problem, but my car only hunts at idle when the engine is warm, its fine when its cold.
It usta do it a little bit before I had high-duration cams, but now is worse with the cams. I was told it may be a leak in the throttle body. I would say its a sensor somewhere.. havent bothered to fix it as it doesnt annoy me too much. But if its a simple fix I will have a go.

[Otaku]

Cars fine now, its was just low on coolant. Theres still a little abit of water leaking from somewhere, but maybe I just filled it up to much.
Thanks for the help!