I have an 85 park ave.,replaced plugs, dist. cap.,rotor button, wires, vacum lines, os & maf sensors.
Service engine light went off.
cooling system circulateing good, rough idle smoothed out.
But idle remains faster than normal, and after dark a glow can be noticed on the front, & rear exhaust manifolds.
When checking the EGR valve, car stumbles a little & then idles down. But when released, idle speeds up again.
What could be going on. Motor seems good & solid for 107.000 mi.

Sounds like it might have a vacuum leak somewhere.

have replaced vacuum lines known!

Check your timing first of all, because you didn't mention that you did that.

Secondly, if your vehicle is carburated, then your carb could need a rebuild, one of the gaskets might be leaking gas into the intake. The choke could be sticking, or the throttle return spring could be worn out and not closing the butterfly valves all the way.

That should give you a place to start!


Good luck,
Ben

thanx 4 the re-plies.
not carburated, multi-port fuel inj.
not saying it's not the timing but it starts & shuts off pretty easy.
could the throtle position sensor be out of adjustment ? or bad ?

If the engine is fuel injected, you must have a diagnostic system. If this is the case, the check engine light would come on if your TPS was bad.

Take off the breather hose to the throttle body and look at the butterfly valve, it should be almost closed, at maybe a 20 degree tilt. if not then something is preventing it from closing, either your idle stop screw, or the actual throttle linkage. The throttle cable could be partially seized, or the idle screw is in too far, if it's adjustable.

If you can, hook up a tachometer to the car to see just how much faster than normal the engine is idling. If it's under 1000 rpm in park, then don't worry about it.

Aside from that, it's hard to determine what the cause is without actually being there.

Good luck!!

thanx again 4 all the help.
adjusting idle screw seems 2 work.
have an 87 park ave. that has no adjustment, & just assumed the 85 was the same.

i would agree with bill, sound like a vacuum leak. check around intake, injectors, egr valve....anywhere vacuum can leak.

i thought the idle screw was ok. but now the car seems to be ( hunting ).
then once up to operating temp. run 4 a bit smooth, then rough, then smooth in a cycle , & sometimes will die.
but starts back easy. i realy need 2 get this car on the road.
please help!