Idle problem
 

Ok fellas please dont get mad if you've seen this thread hundreds of times. I have a '86 Stang w/ gt40 heads, Cobra intake and plenum, E303 cam, MSD 6AL, Edelbrock 70mm throttle body, and it is speed density. Here's my problem.......... My car idles at around 1600 rpm's. I've adjusted the screw on the throttle body and it did absolutley nothing. I know for sure I have no vacuum leaks. How in the hell do you set the idle??? this is truly frustrating and annoying. I have read so many threads bout there must be a vacuum leak BUT trust me I do not have a vacuum leak. What are the ways that you can adjust the idle? Please please somebody help me or guide me in the right direction. Thanks in advance.........

Did you check your TPS voltage?

No I haven't and not to sound stupid but I dont know how, I've seen things here and there bout it but not the full procedure. Im a newbie when it comes to fuel injection cars. Your help will be appreciated.

Ill give it a shot...
First u need to get a multi meter
then turn the iginition on but do not start the car. Then your going to take and find the wiring harness for the tps. Once you find it your going back probe the black probe with the black wire. Then your going to take the red probe and back probe the green wire. You should get a reading anywhere from what i heard of .70v and 1.0v u want it right around .95 and you should be fine. Your going to loosen the two screws on the top of the tps sensor and the turn the tps sensor until u get the reading you want. You may have to enlongate the holes or (make them bigger) If you r not getting a reading there you are going to keep the black back probed to the black wire and touch the red to the orange. If you dont have 5volts there then you have a break in the line somewhere or a fried ecu.. If your wondering why i know this i went through the same bs for a month, i was so angry and then pkrwud saved the day... so i owe my knowledge to pkwud.

my problem was broken wire due to fords wiring setup. The wire broke right where the tps sensor orange wire meets the egr valve harness


hopes this helps later..
oh i also had a lower intake gasket leak that i didnt notice...

thanks bro..........It should def get me on the way.

Ok I got it at .95 but it still tachs at 1600 rpm's what now?? Now Im confused again.

my car did that, and i replaced the tps and it fixed it, but with .95 on it, it should'nt be bad, im stumped.....

Damn its a brand new throttle body w/tps on it to..........Now its starting to worry me. Im resetting the ecu hopefully it will help it.

only one other thing even though you said you dont have a vaccum leak... didd you check the intake gasket the one inbetween the heads and lower intake. Mine stumped me.. no sound or sense of it sucking air but then noticed when it was raining and i was working on my car. Some water leaked right where it meets the heads and it started bubbling. If it wasnt for me being so stupid to set the timing on my car in the rain i would of never noticed

later

Dude I know your problem. My ride used to be speed density. I had the same problem. You have come to the end of your ECM's capabilities. In other words you have done the max that you can do with speed density. It's time to upgrade to mass air. Sorry to tell ya. Good Luck.

i beg to differ look at my mods raptor

Nope Mass Air is not the answer, problem is in cali if I upgrade to mass air my proble is I cant smog it. I got my problem fixed it was the damn idle air sensor. What really gets me is that I had just gotten it back from my mech and he said it was fine...... Fine taching at 1800rpm's ......? GO figure luckily I kept asking enough questions on how to adjust the Idle. Got the fix for free so I cant complain all in all. Thanks for everyone that had an Idea or 2.

Gho$t

gho$t, now that you have the high idle fixed, what you need to do is get the car hot, shut ngine off, disconnect IAC, then set base idle with the idle screw. Then check the TPS after you have the idle you want. Turning the idle screw will change the tps voltage. Then plug everything back in and you are good to go.

You could try cleaning out your Idle air Control valve (Inlet air control valve...same thing). Alot of times carbon will build up inside them and they will stick causing either too much air to be let into the engine or too little. One will cause a low idle, and stalling, the other will cause a high idle. A IAC valve gasket and o-ring will cost less than $5 so it's worth a try. Another trick you could do is try tapping lightly on it with a hammer, you'd be amazed and what a little smack with a blunt instrument can do sometimes :D. Unfortunately because of the design the IAC valve sucks in alot of PCV gasses that stick to the valve and then harden on the shaft causing it to stick. Carb cleaner works great to clean them out.
Good luck,