99REDGT

my idle would bounce from 400-1000rpm only every once in a while, was just being lazy on cleaning the IAC...so today i changed my oil and fuel filter, and it got worse. So no big deal I pull off the IAC and give it a good once over, and now it is even worse. It will hold a steady idle for 20-30 seconds (sometimes longer, sometimes just for a 4-5 seconds) then jumps up to 1000-1100 and then drops to 300-400 like its gonna die, but it doesnt, it will go back to normal idle, then jump again. Is my IAC shot ya think?? Or could it be something else?

Dan04COBRA

Sounds like IAC to me.

It could also be your TPS, but I would save that for last. It's most likely the IAC.

98GTstang

Check engine light come on? Sounds like the problem i just went through last week with my mustang, idle bounced from 400 to about 1100 sometimes and died easy in the cold morning. and if thats the case, its probably the TPS (throttle posistion sensor)

Aixtreme89

Have you checked the voltage at your TPS? it should be between .96-.99 volts. Heres how to do it. Take two paper clips and straighten them out. Then where the plug goes into the TPS, you need to stick one of those paper clips in the back of the connector along side the wire, into the connector. Then stick the other paper clip in the middle spot. Then run your engine at idle, and stick a Digital Volt Ohm Meter, on each of those paper clips and read the voltage. If its to high or low, correct it by loosening the TPS and turning it either clockwise to raise it or counter-clockwise to lower it. Mine was set between 1.15-1.25 with my Accufab 75mm Throttle body thats wht I was having my idle hanging kinda like yours does. So I had to drill out the sleeves of the TPS with a 1/4" bit and it gave it more ability to turn and I finally got it in range, now I am at .96 volts worked wonders on my car!!! Plus mess with the throttle blade stop if you have a aftermarket peice, it will help tune it that way too.

98GTstang

yeah do what aix said, try clearning your throttle plates and all that good stuff while ur at it. a new tps is only like 30 bucks

99REDGT

no check engine light, I didn't think about the TPS...but no it does not die, just acts like it wants to. This is kinda funny too...I just went down to the store to grab a sixxer...and if I am rolling and put my foot on the clutch it will not drop below 1100rpms, it will stay steady @ 1100 until I come to a complete stop then it come down to 400 and start bouncing again. I rolled for well over 1/2 mile and it stuck right there till I hit the stopsign.. I think I might have to perform an exsorcism!

Aixtreme89

mine still does something like that. When I am driving and let off the gas it will hoover at like 1100rpm for a few seconds then drop to 750rpm. I am thinking my problem still is either the PCV valve or EGR valve, and/or AGR regulator. The TPS helped my car when it was sticking at 2500rpm and then dropped slowly after a few seconds. But you should still check your voltage at the TPS so you can exclude or find your problem.

99REDGT

i dont have a meter...but I dont have anything to do tommorrow so Ill buy a new IAC & TPS and see if that does it.

bobjenkins

PCV? EGR? AGR? IAC?

too many acronims!!!!

boss281

+1 no idea what they r talking about....