Hanging RPMs --> HELP!

viperos · Feb 25, 2004

ok, ever since I tried to raise my idle a few weeks back, I've had hanging RPMs every time I shift... used to be perfect, drop right down... I set all my settings back to how they were, but they still hang there! any advice?

-95GT stock everything except CAI and Pulleys btw...

1105 · Feb 25, 2004

Did you play around with that little screw that holds the throttle body flap open? My dad tightened it down some so more air was getting through and that made my cars idle hang there when I went to shift... hell, I could let off the gas and the car would remain the same speed

viperos · Feb 26, 2004

yeah... I did, but I returned it to where it was before hand, but still hanging RPMs... but yes, I do believe that's what did it for me...

91LX_5L · Feb 26, 2004

I adjusted my idle and it does the EXACT same thing now...I had to adjust my idle because my car tend'd to stall when I cranked the wheel, so I had to put my idle up, I lowerd it almost back to how it was and it hangs pretty bad. In city I dont even have to use the gas in lower rpms, or once I get going in 5th gear I hardly even have to touch the gas its pretty bad.

SO 1105...what did you do exactlly i dont understand, I have a 70mm aftermarket throttle body, and there is the adjuster screw which you can open or close (lets more air in if its open, I guess?)

It goes up like 800rpm when i put in the clutch to shift and if I leave the clutch in, it seems to go back down about 5 seconds after I come to a stop...its weird does yours do this? Try it, put in the clutch and let it hang/jump up and hold the clutch in (going downhill or somthing so u can go a distance) then come to a complete stop with the clutch in and tell me if it stops after a few seconds.

I Have been told to try the air-idle-adjuster kit thing, but I wanna research that more. Test your TPS its probaly that, I hope to get around to that this spring just waiting for nice weahter.

1105 · Feb 26, 2004

viperos, did you adjust your IAC at the same time or just play around with that screw? To change your idle you need to adjust the IAC. Look for a little gray (mines gray) rubber cap right behind your IAC and there will be an allen key screw there, turn that to raise and lower your idle. I think clockwise raises it but I didn't pay much attention to it. Then back that screw that holds the flap oppen so that the screw is just barely touching the flap when its all the way closed.

91LX_5L said:
It goes up like 800rpm when i put in the clutch to shift and if I leave the clutch in, it seems to go back down about 5 seconds after I come to a stop...its weird does yours do this?

I cant say mine has ever done that. When I push my clutch in my RPM goes down almost instantly but hangs around 1200rpm for a few seconds before returning to idle... Why it's doing that I dont know but I havent had time to play around with it lately. Try adjusting your IAC like I said above and see what happens.

zenboy99 · Feb 26, 2004

91LX, I have the exact same problem. rpm's jump up about 800rpm when I push the clutch in. I'm going to try the IAC thing tonight.

91LX_5L · Feb 26, 2004

please tell me how it turned out! thanks

viperos · Feb 26, 2004

well, I think I know what you mean 1105... but pics would sure be nice

-got a digi camera lying around w/ some free time?? anyone? just the IAC, and the screws I need to adjust... thanks a lot...

-this is getting really annoying when I goto shift, and I'm used to the RPMs dropping fast, so I give it gas, so it revs up even higher... sounds like a ricer who doesn't know how to drive!!

Black Stampede · Feb 26, 2004

This is very common on our cars.

randomjoker · Feb 26, 2004

Grabbed this off some site.. dont know if it is for our year or what.. but gives u an idea..

Throttle Position Sensor (TPS) Adjustment
Symptoms: high idle, won't idle, dies when throttle is lifter when slowing down, surging idle speed

1. First bring the engine up to normal operating temperature.
2. Turn the engine off and unplug the Idle Air Control (IAC). This is located on the backside of the Throttle Body near the firewall. This device is a round cylinder approximately 5 inches long with a (2) bolt flange and 3 wire male / female plug connector (see pic).
3. Start engine and using a screwdriver adjust the base idle to 700 – 800 RPM using the screw on the throttle body (see pic)

4. Locate the Throttle Position Sensor (TPS) on the Throttle Body. This is also located on the backside of the Throttle Body near the firewall. This is a black plastic device with (2) screws that allows adjustment and (3) wire male / female connector (see pic above). Connect the voltmeter to the TPS and ground. The wire should be either black with a green stripe or green with a black stripe.
5. Using the small Phillips screwdriver adjust the TPS output voltage to approximately 1.0 volts. Most turbo tuners find that setting your voltage to around .90 - .95 volts works best. I set mine around .94 volts.
6. Turn off the engine.
7. With the engine off and the voltmeter still connected move the throttle linkage slowly from idle position to wide open and back to idle, look for a steady increase and then decrease in voltage without any voids or dead spots. Any voids or dead spots would indicate a faulty TPS. If you find a dead spot you need to replace the TPS.
8. Plug in the IAC.
9. Start the engine. The engine’s idle speed should settle in around 1000 RPM. If it settles higher than this, adjust the screw until idle is at 1000 RPM.
10. Go for a test drive and enjoy the smooth idle.

viperos · Feb 26, 2004

thanks... I'll work on that as soon as I finish my HW school comes first before stang fun

91LX_5L · Feb 29, 2004

did it work?

viperos · Feb 29, 2004

kind of... it hangs at low RPMs now... about 2750 and lower.. but at around 3K RPM... it drops like it used to... so racing won't be a problem, just driving around town... I'll keep dinkering around w/ it... I'll let you know if I solved or discovered any secrets in the process

randomjoker · Mar 1, 2004

alright.. glad to hear it helped some!

viperos · Mar 1, 2004

well, I messed a bit more w/ it... and now it hanges if I give it any gas, but if I just let off w/o gas, it drops right down... I would like to just take it somewhere and have them toy around w/ it... I'm beginning to loose my patience w/ it, which is never a good thing w/ me and my car

bjl95mustang · Mar 1, 2004

I've been trying to fix this hanging problem for a while. I thinks it's is something with the iac. At one point I had my car set to where it would idle about 800 with the iac unpluged and I had an idle adjuster plate fom ford. The car ran fine and didn't have a hanging idle or anything like that. But then after I ran it with the iac unpluged for 3 months then it started to not let me shift into gear with out it dying. I have done the whole set the idle with the iac ingluged and stuff like that and it seems that for some reason the iac is not closing fast enough or sticking and that is whats causing the hanging in the rpm's. And besides the connector being different what is the difference of the 94-95 iac compared to the fox iac?

viperos · Mar 1, 2004

btw, I never touched the IAC to begin with... only that little upside-down screw next to the TB... where the throttle cable hooks up... (or, I should say, my dad screwed around w/ it (no punn intended ))

rio95 · Mar 1, 2004

mess with the screw on the plate until the hanging goes away. trust me, that is the problem. i made this same mistake.

viperos · Mar 2, 2004

I've put it back exactly where it was though, and still problems... I even tried 1/4 turns both directions...

bjl95mustang · Mar 2, 2004

Ok I messed with my car tonight and I unpluged the iac then I set the idle to about 700-800 rpm's. I didn't plug the iac back in and it ran fine no hanging idle or anything. I know on my car the hanging idle has something to do with the iac but i'm not shure how to fix it yet. I Can't afford to spend $70 on a new iac right now so it's hard for me to try a new one. I have one that came with my explorer intake I wonder if I splice the connector if It will work?

Hanging RPMs --> HELP!

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