Mustang Boards - High Idle

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- - High Idle (https://mustangboards.com/modular-4-6l-tech/30932-high-idle.html)

Recently installed an Acufab 70mm throttle body and upper plenum, also a BBK cai on my 2000 GT vert. My problem is that when I let off the gas rpm's hang up at about 1500 for a few seconds and then drops back to about 900. Not sure what low idle should be. I checked for vacuum leaks and loose connections. Any help would be appreciated.

Does this happen when your driving and then you come to a complete stop? or is it when you just rev the engine? What other mods do you have besides the ones you listed? manual or auto?

I have the 5 speed. This happens all the time, when I'm driving or just revving. As soon as you push the clutch in it hangs up at about 1500 rpm's for maybe a minute then drops down to about 900. Only other mod I have is Flowmaster cat-back exhaust.

Ok, sounds like the same issue I had pretty much. Here is what I did to fix my issue.

Back the idle stop screw out till doesn't touch the bell crank arm. Use a 0.010" feeler gauge, tighten until gauge just drags between screw and bell crank arm. Remove feeler gauge. Tighten screw exactly 1 1/2 turns. Start the car and make sure it doesn't stall out.

Next, adjust the TPS so the voltage reads .98 or .99. With the connector attached to the TPS stick a paper clip into the rubber boot on the connector where the middle (+) and bottom (-) wires go into the connector. Set your multimeter to volts. If it is already at .98/.99 you are set. If not loosen the screws and turn the TPS till hit those numbers. If you can't you will need to take the TPS off and enlarge the holes. Make sure the TPS is nice and tight when you are done. Don't want it to move.

Last step. Disconnect the battery and let it site for a little while to reset the computer. Reconnect the battery and start the car but do not touch the gas pedal. Let it idle for about 10 minutes. This will let the car learn it's idle.

After I did this my problem went away. It may not sound like it but this is really easy to do. If you don't want to mess with the throttle that ok but at least check the TPS voltage and reset the computer. I redid my throttle body cause my tuner messed it all up.

Thanks, that sounds easy enough. Will let you know how it turns out.

No problem! Definitely post back with you results.

I used your recipe on my Stang tonight and it took care of my idle problem. It lowered my low idle by 100 rpms and it does'nt hang up any more after revving up and letting off. I did have to enlarge the holes on the tps to get the proper voltage. Thanks for some great advice.:)

Sweet!!! glade it worked for you.

Quote:

Originally Posted by bossman302 (Post 335589)

Excellent tech!

Hey MODS!
Can we get a sticky!

You should get your car Dyno tuned as well. Your air/fual ratio is prolly off.

I got mines tuned after I got basically the same intake stuff you got and the tuner said that it was good that I brought it in for a tune, because the 70mm Throttle body was leaning out my ratio.. (to much air). Alot of people on here say that you dont need a tune unless you get ALOT of aftermarket crap done to your car...but..thats not so true.