car searches for idle

[4g63swap]

heres the problem:

car searches for idle between 1000 rpm and 2000 rpm goes up then down and reapeats.

things that I have checked:

vaccum hoses
boost leak
isc is blocked off
and according to my afc II the tps is at 0% when just Idling

what else should I look for?


thanks
Chris

 

[urcnjoe]

A small hair line crack in your exhaust manifold, or maybe a dirty throttle body. There is a large list of things to check for idle surge, just type in idle surge in the search engine and they will come up. Good luck, it is frustrating trying to figure it out.

 

[zippyshoe]

A couple other items you could investigate:

- The throttle position sensor on 2g's contains an idle switch which should be in the closed position when idling (foot removed from the accelerator) and should be open otherwise. The state of this switch signals to the ECU whether or not you are idling. You may want to verify this switch is functioning properly.

- Check the tension of the throttle cable. There should be at least a small bit of slack on this cable to ensure that the throttle plate closes fully at idle. The fact that your TPS is at 0% at idle leads me to believe that the throttle plate is fully closing, but it wouldn't hurt to double-check.

- Maybe run another boost leak test and focus on any possible leaks after the throttle plate (throttle body shaft seals, throttle body gasket, intake manifold gasket, fuel injector seals, etc.) Any leaks in this area would allow air to enter the cylinders when the throttle plate is closed.

Hope this helps you.

 

[ddavisaf]

ISC is blocked off? It shouldn't be blocked off. EGR, sure. But not your ISC.
http://dmtalon.v8eaters.com/ISC.html
Test it. Thoes buggers tend to be the main cause of idle surge.

http://www.dsm.org/how-tos/tttt/tttt3.html Idle Surge FAQ