95 GTS "jumps" between shifts, Searched. Could use some help.

hondarocks61 · Jul 8, 2012

Hey there stang owners, Im having some trouble. I searched quite a bit for information on this subject and even though I found alot of info, Iv tried a few things and Im still not quite sure. My 1995 gts jumps about 200rpm between shifts. I cleaned my aic valve, reset computer, nothing. Then I noticed the previous owner (hack

) had grabbed the idle stud with PLIERS and destroyed the threads...I worked the old stud out and put a bolt in its place, so that the idle screw can now be adjusted easily. The previous owner had obviously messed with it and had it set all the way down (highest idle the threads had to offer.) This tells me he had this problem before and made a half ass attempt to fix it. If I unplug the iac with the idle screw set to run at 650 the car will stall. so im assuming that That part is fine. So... My questions are...

1. The idle AIR screw was all the way in (0 turns out), wtf? what SHOULD it be set at?

2. How SHOULD the IDLE screw be set? Iv heard everything from "its factory set, dont touch it". to "two and a half turns".

3. http://www.muscularmustangs.com/iac.php < I was reading this, and honestly, The tps wire colors arn't the same as mine? Mine are A grey wire, A grey with a red stripe, and a brown with a grey stripe. which is which?! I cant really test the tps if I don't know which wires to poke at!

4. How is the blade on the throttle supposed to hook onto the tps?

If I set the idle with the idle screw and unplug the aic the car doesn't "jump" between shifts...

I REALLY appreciate some help on this guys, I love this car and i want it to be as good as i can get it!

CC'S95GT · Jul 8, 2012

Search "hanging idle"
Also do a search on "base idle reset" Follow it to the letter.
Do you have an OHM meter. to test the TPS. Analog would be better but a digital will work.
Unplug the TPS and connect the ohm meter to any 2 of the 3 connectors. Very slowly turn the TPS and watch the resistance increase. Look for any jumps in the resistance especially in the begining. If you find any replace the TPS.
Because of the age of our cars, the TPS will start getting a dead spot and causing idle issues because it's sending the wrong signals to the computer.

hondarocks61 · Jul 8, 2012

I will try that! Any idea which tps sensor my car takes? Advanced had two different ones?

CC'S95GT · Jul 9, 2012

no idea. i'd write the numbers down from the TPS and take it with me to get the replacement.

hondarocks61 · Jul 9, 2012

I have an aftermarket unit. its a cts? any the factory numbers are "fisfaa" and "f2sfca" I honestly have no idea of telling which is which....

CC'S95GT · Jul 9, 2012

did you test it?

hondarocks61 · Jul 9, 2012

At closed throttle i have one volt. All the way open is 4.69. No dead spots.

toyman · Jul 9, 2012

The TPS should be good with those readings. As to the air bypass screw on the TB it's nornally open about 1 1/2 turns. It's just to tweek the idle. The throttle stop screw shouldn't need to be touched. It's purpose is to prevent the throttle valve from closing to the point where the valve may jam in the bore. Also, adjusting this screw affects the TPS voltage. If you follow to the letter the idle reset procedure you should be fine.

hondarocks61 · Jul 10, 2012

followed this: http://www.mustangspecialties.net/mustang-idle-set-up.html

This one takes the idle air screw into account, which I obviously have no baseline setting for because the previous owner turned it all the way in. Idle at 1.00v still, adjusted exactly by the steps, idles just fine, still revs between shifts. I even cleaned the IAC AGAIN. No change. Am i missing something here?..... On a side note I did spray carb cleaner around looking for leaks and came up with nothing. My head hurts.

ttocs · Jul 10, 2012

what mods do you have on the motor? The rpm's jumping while shifting isn't out of place that is just how the IAC works. You can make a restrictor plate.

hondarocks61 · Jul 10, 2012

lol. Cold air. cat back. MSD ignition stuff. It MAY have a mild cam... sounds a bit lumpy. I was actually planning on making a restrictor plate tonight....