High idle - 86 2.9l

[JohnG]

Gang, new problem this morning. High idle will not drop to normal after warm. Stays at about 2000 rpm.
Pulled codes and got code 32. EGR not responding.
Disconnected the IAC valve and had no change.

What I did the night before… Looked at the air filter. Sprayed some soapy water on the pass side valve cover to look for an oil leak and a possible leaking injector.

Ideas for where to start troubleshooting?
(I tried searching but “code 32” brings few results as it won’t find two letter searches)
Thanks!

 

[franklin2]

Try disconnecting the line to the EGR valve. Possibly it's leaking an letting excess air in? What can happen also, the foam filter in the EGR vacuum valve can get clogged, and then the EGR valve will not release properly. Pull the plastic hat off the EGR vacuum valve over on the pass side inner fender. You will find a foam filter under there, make sure it's clean.

 

[JohnG]

Thanks Franklin2. I’ll start there.

 

[JohnG]

EGR valve checks out ok. I’m going to swap out the EGR pressure sensor since I have a warranty on it.

 

[Uncle Gump]

Sure sounds like a vacuum leak to me...

 

[JohnG]

Strangely. I got the idle to settle down after I cleared the computer. But sprayed throttle body cleaner in the intake it shot up to 2k again and didn’t go back down.

 

[franklin2]

Sticky IAC? You unplugged it but all it has is a spring to push it back shut. Maybe you can take it out and clean it off.

 

[JohnG]

I give that a try. Thanks.

I did start pulling/pluging vacuum hoses to see if I could isolate which vacuum hose might be leaking and the one that had the biggest effect of dropping the idle was the MAP sensor. Is it possible that it could be leaking internally? If it was that would I be getting a code for that?

 

[gaz]

JohnG,

Anytime I get a high idle, I don't check the vacuum lines, I just replace them all and ensure that they all have good clamps on each end. They are very inexpensive and this will either resolve the problem or lead me to the real problem.

To clean the IAC, just be careful. Once the components of it are clean it should have the correct movement.

Just evaluate, inspect and carefully handle each component of interest. You will isolate the culprit.

 

[franklin2]

I give that a try. Thanks.

I did start pulling/pluging vacuum hoses to see if I could isolate which vacuum hose might be leaking and the one that had the biggest effect of dropping the idle was the MAP sensor. Is it possible that it could be leaking internally? If it was that would I be getting a code for that?

MAP sensor is a tricky one, since it's what the computer uses to measure the vacuum of the engine. So it's going to have a large affect on how it runs if all of a sudden the MAP is not sending the proper signal back on the wires to the computer.

 

[ecgreen]

Sure sounds like a vacuum leak to me...

Doesn't cost much to just replace all Vac hoses.

 

[JohnG]

Thanks all for the help. I’m still looking.

I replaced most of the hoses last year but certainly can again.

Tell me this. There are vacuum hoses going to the housing under the air filter. What do they do? Could it be leaking inside there?

 

[franklin2]

That thing under the air filter is a vacuum reservoir. It stores vacuum for the controls so when you are pulling a long hill the controls still have some vacuum to work with.