i have an 85gt 4 speed that has a high idle . anywhere from 1000 - 1400 rpm. it seems like ive tried evrything. my mechanic put it on the diagnostic computer and came back with no codes. he took out the hoses from the manifold ( the main 2 that go out to the brake and other little vacuum thingies on the engine) and covered them , and also blocked off the egr from both sides and still the idle wont settle . i dont know what else it could be. im stumped and dont like the idea of wastin extra money on gas for a bad idle. can ennyone suggest something i might have missed?

thanx
romeo
85gt 4 speed
stock

for now anyhow

IAC?

if thats the valve that is on the throttle body that u screw and unscrew to adjust the amount of air to control the idle, yes , we've tried that too. the idle constantly goes from 1000 to about 13-1500 up and down, not sharp;y but kinda gradually like its searching.

Thats kinda weird that you have no codes if the idle is that high...is the temperature getting to 180 at least when warmed up???? If the computer thinks the engine is still cold that idle is normal, but if it is seeing over 170 it should throw a IAC code because it will be all the way closed trying to bring the idle down...could also be intake manifold gaskets bad, 1 of the three but if everything else is right it should throw a code...

Did you remove the IAC and clean the seat area with carb cleaner or fuel injection solvent?
Did you check for a steady alternator output? Does the ECM show the neutral/park safety switch on or off? Does the throttle blade stop screw look like it was tampered with or perhaps loosened up? Lastly did you do a cylinder leakdown or compression check? All of these factors can influence an unsteady idle condition.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://www.turbochargerpower.com/turbo.htm

alternator is new, mechanic said all sensors were fine, id like to try and replace the man gasket next. hope that helps. ill check the idle screw thingy next too.other than that the car seems to run ok, diesnt seem to make any power until the damn thing is almost at redline tho. maybe i have a 4.10 4 speed.

i knew someone with a fiero with only 30,000 miles and did the same thing you are discribbing, did not throw a code and had no power until like 4000 rpm, also had trouble idleing... after he replaced just about everything in the car (replaced eveything from the fuel pump to the injecter, computer to the coil to the plugs.. had it leakdown/compression tested...) anyways it ended up being a bad 02 sensor. you might want to try that, only like $50 and could be it...

Kyle

Did you unplug the battery?

If not, do it, then relearn the idle. I believe it's start the car and let it warm up to operating temprature, drive the car for 10 miles(or minutes(?)) using gradual acceleration and not keeping a steady speed(vary it up and down).

Just a suggestion if you've tried everything else.

I remember a problem like this being the o-rings on the injectors but I might be wrong.

if it were the o rings on the injectors wouldnt i have a gas leak and smell gas on the manifold?

and what is a good way to tell if the manifold gasket is bad?

A vacuum leak in the intake tract somewhere. On a V6, there's a lot of places it can leak.

[This message has been edited by Scarecrow (edited 06-13-2003).]

Yeah like a craked plastic hose or something. Do this: crank up the car and run water from a hose all over it (not on the distributer or anything) and listen carefully. Have the water on low ans run it all over the intake and around that area where the vacuum hoses are. If you hear
SLLLLLUUUUUUGHHHHHHPPPPPPPPP from anywhere there's your leak !

For the lower intake you can plug up the holes in both valve covers and with engine running if you hear a whistle or the idle comes down you have a bad gasket...