1991 N/A

I took the UIM off to rebuild the OMP lines and now my idle sits steady at right around 3000 rpm.

The coolant system also appeared to be air locked since the upper rad hose, and coolant hoses going to the TB get hard once the engine heats up. I tried burping the coolant system and no air came out. Can the AWS cause a high idle if the coolant isn't flowing properly?

Also the downpipe is getting cherry red. Lack of coolant flow?

• I've checked the throttle cable and cruise cable they are fine.
• I cleaned the UIM/LIM surface and put in a new gasket.
• I sprayed water all around the UIM to check for vacuum and air leaks.

I plan on draining the coolant and just refilling it. My thinking is that when I took the 4 coolant hoses off to get the UIM off I introduced air into the system I can't burp out.

 

Probably a vacuum leak causing the high idle. Why would water be an ideal way to check vacuum leaks? Buy some carb cleaner instead. At home it can be a pain sometimes to find a vacuum leak, glad i have a smoke machine to make short time of it.
Under 15psi of pressure the upper hose will be stiff when hot, but yes make sure it's bleed properly.

 

I'll try carb cleaner. A spray bottle with water was just what I had available and I figured it would lower my idle rather then raise it. I didn't want to use something that raised the idle since it was already 3k+ and the engine was cold.

I went through the vacuum diagram and traced it in MS paint to add some color I'll recheck all the vacuum connections.

I also have a electrical connector coming out of the harness between the water pump and UIM. I can't find what it plugs into. It has a single wire going to it which is black with a white strip the connector is grey. My BAC, secondary injectors, TPS, OMP are all plugged in.

 

I figured out what was wrong and the car idles great at 750 rpm now. Turns out my TPS was way out of adjustment it was reading 4 Kohms at idle. I got it down to 1.2 Kohms and it runs great now.

I also replaced about 85% of the vacuum lines and took off the UIM again and replaced all the vacuum lines under it. The TPS adjustment is what fixed the idle though.