hELLO, i am new to the boards. I have a 91 firebird 305 tbi with a very rough idle. I changed the iac motor last nite and tried to adjust according to the procedure i found on here. Now the car wont idle below 1200 rom in drive and the idle screw is completely off the throttle shaft.
Any help would be greatly appreciated.

 

Welcome to the baords. There are many things that are causing your symptoms. You could have burnt plug wires, bad coil, bad TPS, clogged fuel filter, or bad plugs. How long has the car gone before its last tune up?

 

car was just tuned up shifty, still had a rough idle in closed loop so i changed the iac now i cant get it to idle below 1100 rpm in park and about 800 rpm in drive.
thanks for the reply.

 

shouldn't the stop screw hold the throttle plates slightly open ? i look for a tps voltage of about .5 fully closed.

 

Could be the initial timing was set incorrectly. Did you disconnect the timing control connecter link between the comp. and dist? When I bought my car, it ran like that. I checked it before I disconnected it and it was right on! I disconnected it like you should and it was 28* retarded. Poor comp. was trying to compensate for that and was screwing everthing up! Before I reset it, I was only getting 150mi to a tank of gas. after, 300+.
It could be too far advanced also!