my car will not idle below 1500rpm!!! help

[Pur Pony]

I have an icon twin turbo car with a 306. Over the winter I removed the smog equipment and egr. Changed some vacuum lines around along with some wiring.

Now the car will not idle down. It idles at 1500 rpms until right when you let the clutch out it drops to 800rpms. I am using a tweecer and its set to idle at 800rpms. Once I am out driving the car around and I let off the gas in gear moving the car hangs at 2000rpm.

I did have the battery disconnected and my IAC sensor off. A friend said I need to drive the car for a while for the IAC to relearn?? I have done this and it doesnt seem to work.

anyone else have any ideas? I thought maybe a vacuum leak but would a vacuum leak cause a steady high idle or a surging idle?

thanks for any help!!!

 

[jrichker]

Vacuum leaks usually cause a high idle.

 

[Pur Pony]

I just changed every vacuum line on the car and its still doing it!

 

[jrichker]

Connect a vacuum gauge & see what you get for readings.

 

[DW5.0L]

What about the TPS being out of adjustment? That can cause a high idle.

 

[jrichker]

What about the TPS being out of adjustment? That can cause a high idle.

Good point. Here's a TPS adjustment proceedure.

Try this... Currently there is some dispute about setting it at .99 volts but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a Digital Voltmeter (DVM) to do the job.

The Orange/White wire is the VREF 5 volts from the computer. You use the Dark Green/Lt green wire (TPS signal) and the Black/White wire (TPS ground) to set the TPS

Here’s a TPS tip I got from NoGo50

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better.

(copied from MustangMax, Glendale AZ)

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

3. Always reset the computer whenever you adjust the TPS or clean/change any sensors. I just pull the battery lead for 10 minutes.

4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the computer and start it up. The key is to adjust the TPS voltage and reset the computer whenever the idle screw is changed.