Discuss 1991 Mustang gt idle air control problems on AllFordMustangs.com, the place for Mustang enthusiasts.
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Im having problems controlling my idle. I've taken apart the iac, cleaned it and put it back together. seems to have made matters worst. It now idles higher and is very irratic. I've also messed around with the tps sensor. havent been able to get that .98 -.99 reading. any help would be great.
i thought maybe it would be the iac. i tap it with a screwdriver and it seems to settle down for a few seconds, then starts to act up again. another thing i did was drive the car about 20 miles in stop and go traffic and didnt feel a difference. wierd right.
Do an IAC search on this site...there is a specific order Ford recommends regarding timing, TPS, unplugging the IAC, disconnecting neg battery cable and so on. Worked well for me..if you cant find it, let me know and Ill dig through my print outs.
1988 GT Vert 70K
BBK Fender Cold Air, Ford E303, Cobra Intakes, Kirban Adj Fuel Reg, FRPP 65mm TB, 19# Explorer injectors, MAF Conversion, TF Valve Springs, BBK Equal Length Shorty's, KYB's all around, Magnaflow 2.5 high flow cats H pipe, American Thunder's, 3.73's, Speedo gear, AOD w/Performance Automatic street/strip valve body, Overdrive A+ Super Servo, 2-3 Accumulator upgrade, Urethane motor and tranny mounts, Smog, EGR and A/C delete
It could be the TPS, you could check it to see if it's operating right. You pierce the black and green wires and connect a digital voltmeter, and then turn the key on. Slowly open up the throttle and watch the voltage, if it isn't a steady increase or if it drops AT ALL, or even goes to zero, it needs to be replaced.
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ok, so i tryed it and the numbers were high 2.34. the lowest i got it to was 1.35. i ended up taking out the tps and making the holes bigger so i could move the sensor around more. it worked i got the numbers down to 1.02. now should i disconnect the battery for 1/2 an hour so the computer erases its memory. when i started the car it seemed fine. true test will be tomorrow when i drive it to work.
ok, now the car is idling at a constant 2000 rpm. i dont know what else to try. should i take apart the throttle body and clean it. should i replace the tps, should i replace the iac. any advice would be helpful at this point. thanks
well you could try disconecting the tps then it should just revert the the computers pre-determined settings.. did it just start acting up out of the blue? also have you messed with the screw that sets the idle? also im guessing you have a mass airflow car so if u had anykinda vacume leak it would idle high do you hear a hiss when its runing? take carb and choke cleaner and lightly spray around ur t/b intake and vacume lines if u hear the idle slightly change at all that would signify a leak.. just something to try
well here it goes. i bought a new tps sensor replaced that. took out the iac again cleaned it and took apart the throttle body and cleaned that as well. put it all together, reset idle with screw on side of throttle body. i disconnected the battery for 1/2 hour, restarted car let it run in driveway for 20 mins. i drove it to work this morning, didnt beat on her. all seems good for now. lets give it a few days.
everybody thanks for the info. you're all very helpful. greatly appreciated.