Well from a cold start my 86 GT with 188,000 kms on it (117,000 miles) idles at about 2000 and keeps it steady until it starts to warm up to normal operating temp. Once it gets to normal temp is idles between 1100 and 900 rpm. The intake gaskets are new, and im working on fixing the EGR, but when it's running it sounds like it starts choking itself and the sounds like somone slightly taps the throttle to get it back up to 1000 rpm or more, and it continuously does this and it sounds like its going to stall but it never does. Anyone have any ideas? Pics would be good of where and what to clean and what else to check out.

Thanks

sounds like it needs a tune up. fresh plugs, wires, cap, rotor, etc. it shouldnt "chug" at 900 RPM. also, if its never been done, new MAT & CTS sensors (Manifold Absolute Temp & Coolant Temp Sensor) help ALOT - also, any other original sensors would be good to replace - like the MAP, and the O2 should be replaced regulalrly, so if you havent, defeintly replace this one. the feeling of someone tapping the throttle is the stall saver kicking in. cleaning the IAC is pretty easy - take off the rubber snorkle between the throttle body & air cleaner housing, you'll see a little 1/4" hole on the throttle body. this is the IAC hole. shoot some throttle body cleaner down in there. the car will want to stall, so you may have to goose the throttle a bit. try to hit the throttle as little as possible, forcing the cleaner down the little hole.

anyways, replace the MAT & CTS, and the O2 if its more than 3 years old.

the thing is that it has gotten a complete tune up either then the sensor, all bosch ultra premium wires,cap,rotor, and ac delco plugs, i thought that the iac is the sensor beside the tps? the one that has a hex shape for a wrench to grip it

yes, the IAC is that hex thing you describe. it is NOT a sensor, it is a solenoid, that opens & closes the air passage thru that 1/4" hole in the throttle body - a controlled vacuum leak, basicly, to give the mtoro enough just air to idle, with the throttle plate closed. spraying the cleaner down the hole cleanes the actual valve surfaces. if you repace the IAC, you remove that hex thing, and you'll see what I mean. the MAT sensor is the one in the air filter can, the CTS sensor is the one on the intake manifold, sticking out horizontanly towards the pulleys.

ok, how much are all these sensors?

CTS & MAT are $20-$25 each, O2 is $35

When your engine is warmed up the IAC is closed. the idle is controlled from the ignition module. when it is warmed up you can disconnect the iac and it will make no difference. Mine does the same thing and I have cleaned and adjusted everything, still the same. so there is one sensor that I have not changed and that is the one under the thermostst housing (ECM temp sensor). this will be next. if you clean the iac make sure you adjust the pintle to one and one eight inch from the pintle end to the gasket on the body.
Don

My 4 cylinder was doing this, so I pulled off the throttle body, and the egr passages were plugged, so I clean them out. Then I cleaned out the iac passage and the iac itself, and it runs great now.

alrighty ill try all that stuff that you guys listed.

I'm having the same problems with idling, did any of these things work for you olaf_fiero27?

quote Originally posted by ka4nkf: When your engine is warmed up the IAC is closed. the idle is controlled from the ignition module. when it is warmed up you can disconnect the iac and it will make no difference. Mine does the same thing and I have cleaned and adjusted everything, still the same. so there is one sensor that I have not changed and that is the one under the thermostst housing (ECM temp sensor). this will be next. if you clean the iac make sure you adjust the pintle to one and one eight inch from the pintle end to the gasket on the body. Don

That is interesting, I had a warm/hot idle problem that was corrected once I cleaned the throttle body and IAC. It would idle at 600-800 rpms and die on occasion.
BUT I think that the IAC was not adjusted correctly, when I removed it was only about an 1 1/32" from the gasket surface to the tip now it is closer to the 1 1/8" recomended.

http://fieroswest.westcoastfiero.com/Tech%20Scene/Idle/Tech012002.htm
http://fieroswest.westcoastfiero.com/Tech%20Scene/Idle/iacadjust.htm
http://fieroswest.westcoastfiero.com/Tech%20Scene/Sensors/TPS/tps.htm
May Help

quote Originally posted by ka4nkf: When your engine is warmed up the IAC is closed. the idle is controlled from the ignition module. when it is warmed up you can disconnect the iac and it will make no difference. Don

Just for clarification.. I thought "from an idling standpoint" that the IAC is open enought to allow an idle of say 800 rpm. If the engine is in a cold start the IAC will open a little more to increase the idle. This message comes from the ATS "air temp sensor - or equivalent". Once warmed up and idling the IAC is still open to maintain the 800 rpm. If you disc the IAC connector "with engine idling" the position of the IAC pintle will stay in that position "open" even while driving down the road.

Reconnect the ATS plug... Now when you shut down the warmed engine via the key, the IAC sets itself open for the next start. Hit the key and engine starts and maintains correct idle without any pedal-work.
Thats how I thought it worked.. but I could be wrong.