i could use some help! i have a 90 n/a.the car will idle at start up 2000and 2500rpm.
i have the idle screw backed off all the way(it wont go back anymore)i have adjusted the tps with the 2 lights and the multimeter ,no help.change the bac for a known working bac.tried adjusting bac screw on both, no help. changed gasket on injectors (all 4) because they looked bad,no help performed full tune up several times(everything oil,plugs, wires & all filters). checked all vac hoses it looked like none were leaking (even used snoop(leak detector) to confirm no vac leaks). now after driving with a/c on for 30 to 40 minutes idle will drop to a range of 600 to 1500 rpm but no always ,most of the time.
while in the 600 to 1500range if i turn off the a/c the car will turn off 1/2 the time other times it feels like it will turn off so i keep the idle up to 1000 to maintain the engine.
i have read thru various threads and have not found anything that helped.

thanks
Al

 

I hope you do know your car has a cold start assist. Same with my 90 GXL.
When engine is cold it will idle around 3000 then get lower and lower as the engine warms up.. After engine is fully warmed up it should hold a steady idle around 750.

 

Yeah, it idles high due to the cold start assist. The reason it dies when the a/c (which raises the idle) isn't on is because you've done all that other stuff to lower the idle. put everything back to normal and see if it idles well once it warms up.

 

the car is warmed up i would drive the car 30 to 40 minutes thats an average of 45 to 50 miles. the car will not come down at the beginning sometimes after this drive i mentioned (did i mention sometimes). according to many of the threads i have read and my own research the car is where it should be. i am open for any other suggestions.
thanks
Al

 

can anyone out there help i am open to any suggestions.
thanks

 

Well, by the idle screw, I assume your talking about the one on the top of the TB area, correct?

The first thing I would do is scan for codes. A bad thermosensor tends to wreak havoc on S5 cars.

 

i seemed to have the exact same problem a few years back.it was a simple fix and is quite common to the 7. the tube/hole that the antifreeze flows thru to the thermowax coil is probably plugged. the thermo wax will not melt without the hot coolant getting thru to it but it will melt from engine heat when the engine is very wam.it was a quick and painless fix, cost me about $150. no parts just labor. intake manifold has to come off to get at it, i think.

 

j-rat
yes thats what i mean, the screw on top of the tb. i will look up how to extract the codes and check out the thermosenor.
on a personal note i just changed the neck that houses the thermostat it looked ok. but in any case i was unable to change the thermostat due to time constraints.

 

1fastrx7
what is a thermowax coil? can you send me some info on this since i have no idea what you are talking about? i would like to research this .
thanks