idle screw on the throttle body

[jakesspv6]

So I've been having issues with my idle hanging around 2k rpms after acceleration and have been trying to figure out the problem. I have cleaned the MAF, IAC, and TPS. while I was checking all of the vacuum lines I noticed that the idle screw in the throttle was missing. Maybe it fell out one day and I never noticed, but I believe it is the reason for my hanging idle. I wanted to see if anyone knew the dimensions of the screw or possibly how and where I could get a replacement?

 

[mwolson]

You probably could get a replacement screw from about any junkyard Mustang of a similar vintage, just guessing.

To set it, with the engine idling, you will need to datalog the ISC_Duty_Cycle and VERY SLOWLY turn the screw until the duty cycle is settled at about 30-35%.

 

[1996MysticSnake]

With the car running disconnect the iac and set that screw so the car idles between 625-700. Then you need to adjust the tps so the voltage is close to .98..... Make sure u you use the ground wire going to the tps, if you ground it somewhere on the car you will get a different reading.

Reconnect the IAC, start the car up and let it idle for a while and watch the IAC duty like stated above also ISC integrator should be close to zero or even a little negative

 

[CzchMex]

I don't think a missing throttle screw will cause a hanging idle. Possibly a surging idle. The screw keeps the blade open just enough. No screw means it could close further letting the only air in through the IAC.

I had a horrible hanging idle problem as well and found out it was bad O-rings in the shift of the IMRCs. Not sure if you are deleted at all. But I'm currently fixing that problem. A smoke test or a can of carb cleaner can identify that leak real fast.

Hope this helps if the screw does not

 

[jakesspv6]

I sent my throttle body back to accufab since they told me that would replace the screw and re calibrate it. If the idle doesn't fix I will look into that. thank you.