My head hurts trying to find out how to adjust idle....

[bassman]

My 93 festina has 275000 k and is getting old... I fix what it needs and today replaced plugs, wires , cap rotor in hopes of my idle issue.
it runs grat but idles rough and dies.. when I go from reverse to drive.

I just want to turn up the idle a few hundred rpm and that would fix it but how do I do it?

thanks.

[crazyrog17]

Could be a gummy or failed IAC solenoid valve. Idle air control.

[TominMO]

Might also have an issue with an old vacuum line. Just turning up the idle might work, but is not addressing the real problem.

[bassman]

where is the IAC ? I have a haynes but we are redoing our home and my shop looks like home depot after a hurricane..

[bassman]

I looked over the vacume lines and pulled on them looking for sracks , sprayed either and no jump in rpm ..

[sketchman]

It has a blue connector on it. There is a hose going from the hard intake pipe just over the valve cover to it and one from it going into the driver's side of the intake manifold where it is also bolted to.

If you can upload a pic, I can trace the lines for you with a neon green line if that would help. Get the driver's side of the engine in the shot.

[FestYboy]

Bassman, if you need to do a base idle adjustment, place your hand on the throttle body inlet. now look about 1" back and 1" to the right of the driver side of the inlet. you should see either a 1/2" round piece of rubber OR a 3/8" hole with a flat tipped screw head at the bottom. if you see the round piece of rubber, pull it out and look for the screw head. back the screw head out 1/2 turn (lefty loosey), and test. then continue to back out in 1/4 turn increments untill idle is ideal (~700 rpm warm).

[denguy]

I tried to adjust my idle with that screw Festyboy mentioned and nothing changed no matter what I did to it. I get the feeling that the computer has something to do with idle.

[sketchman]

Pull the plug on the IAC and see if it still won't let you adjust it. I have no IAC, and the screw works fine for me.

[miami man]

one time i accidently found out my bad iddle problem by dropping a wrench on the wire leading to the the part ththat covers the air filter and it has a plug in . start shaking some wires to see of you have a bad connection or bad wire grounding against engine by accident.

[FestYboy]

I tried to adjust my idle with that screw Festyboy mentioned and nothing changed no matter what I did to it. I get the feeling that the computer has something to do with idle.

nope, the IAC is a stepper motor/thermostatic plunger combo. when the engine is cold, the plunger can be controled (to a point) by the ECU, but once the engine gets above 130 or so, the plunger is supposed to close and the base idle screw takes over for idle speed duty.
Denguy, make sure your engine is up to temp before adjusing the idle speed screw. if the engine speed is too high with the screw all the way in on a warm engine, there's an issue with the IAC plunger (stuck open), or there's a vacuum leak.

[bassman]

I pulled the rubber plug and gave it a 1/4 turn and I am good to go!!

[FestYboy]

good to hear!