Tb42e idle

[Tassie4x4]

I have a tb42e (92 model) with a an auto that has a manual valve body fitted. I would like to decrease the engine idle speed from 800rpm to 600rpm. Currently I can screw the adjustment in at the back of the plenum and it doesn't make a difference. It's as if the ecu is controlling it to 800. Is there a way to change the computer idle speed without using a scan tool? I have disconnected plugs and tried several different variations but had no luck. Your help is appreciated.

[Bloodyaussie]

What is your TPS set at??

[Tassie4x4]

I haven't checked the TPS, but I have cleaned the IAC valve and tested the temp sensor and they were both good. I did find a vacuum leak which has made the idle stable at 800revs. I'll have a read of he manual and check the TPS, and let you know how I go. Thanks for reply.

[Tassie4x4]

Timing was good too.