Idle problems. PLEASE HELP
 

I just got my car running today with the new short block. The problem I have is when I give the car a little gas the idle stays high and then sloowwwlyyy comes back down. Also when I am driving the car it rev's up to about 2200-2800 and stays there even if I put the car in neutral and just coast. Then when the car comes to a complete stop the idle comes back down slowly?? It is a 5 speed car. Also when I disconnect the Idle thing (forgot the name of the sensor) the car seems very responsive and rev's quickly and come RIGHT back down instantly? Is there something I need to add? Can you run with the sensor unplugged? This is very annoying. Its like having your cruise control on all the time. PLEASE HELP ME!!!! Also the car seems to be pulling hard as Hell. Thanks



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1994 Mustang D.S.S. pro bullet 306, TFS heads, cobra Intake, 24lb inj, E-303 cam, 70mm throttle body, 75mm maf, 93 computer conversion, 3:73 rear, Kenny Brown subframe connectors, Eibach drag springs, Megabite jr's, Long tube headers, off road exhaust, 2 chamber flow masters...

It's gonna idle high when it's cold. That's normal. What's not normal is 2200-2800. Putting the car in neutral and coasting shouldn't change anything. As long as the drive shaft is turning and the sensor on the tranny senses it, it will keep the idle high until the driveshaft stops turning. This is what keeps your car from stalling when you slam on the brakes.

What thing are you disconnecting? The sensor on your tranny or the plug going to the IAC? If it's the latter and the car runs bettter without it, that probably means you have your idle adjustment screw turned in too much.

You should unscrew it until you can fit a .010" feeler gauge between the adjustment screw and the stop plate.

Turn the screw until the gauge gives you a little (very little) resistance to pull it out.

Turn the screw another 1 1/4 turns.

Reset computer procedure
Disconnect the negative battery cable for 10 minutes and then reconnect it.

Turn off all of your accessories and start the engine. Let it idle for 10 minutes and then shut it off.

Turn on all of your accessories and start the engine. Let it idle for another 10 minutes.

Go for a drive and see how it runs.

If this doesn't work, get yourself a multimeter that has a digital tach. Hook it up and start the engine.

Disconnect the IAC.

Turn the adjustment screen in or out until you are idling at about 700 rpms.

Plug the IAC back in and then do the reset computer procedure.

Get back to us with the results.

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351W 89 Mustang GT Convertible

There is an allen screw on your IAC valve at the top. Turn the clockwise to decrease your idle if the previous post doesn't help. I've been messing with mine a bit and it's perfect at 900 or so, but it is better to have your tps set at about .98 first, then adjust that. I've messed with my idle screw a bit, so my tps might be off a little.

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Clint L.
White 95 Cobra #3637
58cc GT40X heads with mild porting, Crane 2031 cam, FRPP 65 TB, 1.7s, Cobra intake, homeade cold air, 155lph, pullies, Tokico Illuminas, C springs, GW lower control arms, Steeda CC plates, aluminum driveshaft, Steeda quadrant, MSD6A, Mac shorties, off road hpipe, 2 1/2 ultra flows w/ dumps, R hood, Euro clear corners, stock 3.08s
13.61 @ 104.7 w/ 2.22

what if when you disconnect the IAB the car dies? OR it will not start with it disconnected?

That would indicate that the IAB is working since it makes a difference as to how your engine runs (or in your case, doesn't run).

It may be different with the 95 as to how to adjust the idle. What you may want to do is turn the adjustment screw in with the IAC disconnected until you can get it to barely idle then hook up the IAC and reset your computer.

Remember that when you set your idle you will be changing the throttle position so you also have to set your TPS at the same time.

Saltmaker, were you able to fix your problem or do you still have it?

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351W 89 Mustang GT Convertible

Salt maker. Had the same problem. Seems the connector on the idle speed motor gets corroded. I got a replacement connector from parts store, cut the old one off, twisted the wires to the new connector, electrcal taped them and the problem ended. Good Luck!

Re: Idle problems. PLEASE HELP
 

what is iab?

Re: Idle problems. PLEASE HELP
 

IAB = Idle Air Bypass. It's the valve on the back the throttle body.

Re: Idle problems. PLEASE HELP
 

Thanks, Mr. Flyer.