3sge idling issue st206 Curren

[edwagon]

Ive just bought an st206 with the 3sge engine, and it doesn;t like idling when its warm.
At hot idle, it'll sit happily on 900rpm for 30sec or so, then drop down to 800 and sit there fine, but after another few seconds it'll drop down around 500-600rpm and only just run, until it either dies, or the ecu catches it with a great big rev up to 1100rpm or so, and then repeats the cycle.

I have replaced the plugs and given the throttle body a clean, and it has improved the general running of the car alot, but the idle issue remains.
It is also a little better with the aircon on, but still does it.

Is there anything that commonly goes wrong with these? The IACs known to be weak? (the greenish box under the throttle body)

Any suggestions?

[FXGTV]

Maybe you're AFM is poked. I know when mine died it couldn't hold the idle for very long, like you're describing.

[edwagon]

Cheers for the suggestion - I'm pretty sure mine is just a map tho, not afm. Shoulda mentioned that!

[RunningRich]

Your idle speed controller may be a bit sticky. One thing you can do without being too invasive is find the ISC on the throttle body and loosen the two screws slightly that hold the spring holder in place. This allows to to turn the ISC spring slightly and from memory will chance the twist in the spring, hence changing how much the ISC is open. If this is dramatically wrong you get a bad idle.

It isn't hard to remove th throttle body and ISC to give them a proper clean. Also check the electromagnet on the ISC to make sure it isn't cracked to allow moisture in. They can short out and cause the vital smoke to escape from the ECU.

[Jazza]

You got the right plugs? I know repco commonly try and sell me different plugs to what i ask for telling me they are the same (when theyre not).

[KinLoud]

I might have a complete ST206 3sge throttle body lying around somewhere...
If I can find it you can borrow it to see if that solves the problem.

Ken
Auck
021 408 863

[ROBODISCO_20v]

Could also be the EFI water temp sensor thats faulty. It's a pretty common problem on Nissan's. Causes the idle to do strange things like you've described.

http://www.toyodiy.com/parts/p_J_1996_TOYOTA_CURREN_ST206-DCMVF_8404_2211.html

[KinLoud]

Can't find the throttle body...
Must be in my pile of junk in Hamilton. Will look for it when I get down there next. Sorry

Ken
Auck
021 408 863

[edwagon]

Awesome - thanks Ken!

I'll pull the TB off over the weekend and see if I can see anything obvious, otherwise will just replace it