mark's91-XJ

1988 4.0L
most of the time it will idle high when i start it, then come down to an idle but uneven rpms, i repleced the icm and cleaned the TB no change. any ideas?

Caish

When you cleaned the RB did you make sure the idle speed motor was cleaned up too?

mark's91-XJ

i replaced the ism no change help

Caish

Ok might be a vacuum leak, use some starting fluid and start spraying around the intake and the vacuum lines looking for a change in engine sound. You can use brake cleaner, or carb cleaner too.

mark's91-XJ

i did that and i didnt notice any change , all the lines seem to be in good condition, but im with you on that one i just cant find the leak, how much of a change would the motor make?

Caish

If there is a leak the fluid would slow the leak down and it should settle into a normal idle till the fluid evaps. One thing I would try, is pull the throttle body off again, and use grease on the gasket to make sure its got a good seal.

How is the voltages? ISM and throttle Position sensor.
How is the grounds on the right side of the engine?

mark's91-XJ

i havent checked but i will when its light, anything else ?