4AGE Idle surging

[Dragger_Dan]

A problem I have heard is fairly common... A bluetop 4AGE suging at idle. The engine runs fine everywhere else, no problems while revving, just surges at idle. When in drive (auto AW11) it does not surge with no revs on. Anybody had this before? What is the first place to look? Have replaced most of the vacuum lines to no avail. Any help would be great.

[pc]

I've had this before and it was in 2 cars that had water (coolant) problems. i.e blocked radiator and leaking pipes etc. I think it is something to do with a temperature sensor getting erratic readings from cold and then hot water... but this has just been my guess. once the coolent problems were sorted the cars idled properly.

[Dragger_Dan]

Thanks dude, I will have a look at that. I did replace a decayed bottom hose on the car, so I may need to bleed the system again. Any other suggestions?

[85AW20v]

Take the throttle body off and clean it all out. They clog up a bit and the bypass doesn't work correctly. Make sure the 2 small coolant lines are clear as well. Quite often it is air in the system that causes the erratic idle as well. If you can, when bleeding the system, jack the back of the car up to make sure all the air comes to one of the 3 bleed points. There's one on the left side of the radiator, one where the heater pipes come through the firewall and the last one on the thermostat housing above the gearbox.

[Stealer Of Souls]

In my one the cold compensation bit of the throttle body had died... still dead to this day. Getting another one soon.
Problem being, the throttle bodies are sealed, you can replace just that bit...
That was my problem.