iac or tps

96gtstang · 03-26-2008, 11:26 AM

my car is a 99 gt 5 speed- lately when getting off the highway or anytime im holding a certain speed/rpm for long period of time then take the car out of gear to slow down or whatever it revs up and stays up until i shut the car off and restart it. for example today i was goin down the highway at 2k rpm get to off ramp take it out of gear and the car just shoots up to 3k rpm and sticks, i reved it and it just stuck at the higher rpm i just reved to so i had to shut it off and restart, it just kept doing it the whole drive home and seems to be getting worse. I used to have this problem once every couple weeks but lately its more an more frequent. Im thinking its either the Throttle position sensor or the idle air control? what do you guys think

96blackgt54 · 03-26-2008, 02:44 PM

Go out and get it to do what it's doing and unplug one of them and note the diffrence.
To me it sounds like a TPS. I've had the same problem with other cars and turned out to be the TPS.

96gtstang · 03-26-2008, 09:41 PM

yea im thinking its the tps as well but the reason i also have afeeling it could be the iac is because its like somthing is getting stuck open which makes the car want to just stay reved up with extra air and fuel, im thinking the valve on the iac might be stuck? anybody else got an idea

thebeastum · 03-26-2008, 10:39 PM

tps more than likely. when an iac motor goes bad it shuts of the motor.

00whtgt · 03-27-2008, 07:25 AM

Sounds like the tps. I had my IAC screwing up and it would do the opposite, drop to real low rpm's and sometimes stall the car out.

Scott

*Randy Stinchcomb* · 03-27-2008, 08:03 AM

sounds like an IAC problem, thrttl cable sticking (which there was a TSB about the thrttle cable hanging-up at the carpet) or a vac leak........just an FYI: the TPS's used on the Modular cars since 1994 has been one of THE Most Trouble-Free TPS's ever used by FoMoCo, so I doubt your problem lies wth it....stock thrttlbdy or aftermarket?

B-rett · 03-27-2008, 08:37 AM

Quote:

Originally Posted by 00whtgt

Sounds like the tps. I had my IAC screwing up and it would do the opposite, drop to real low rpm's and sometimes stall the car out.

Scott

hmm this seems to happen to my car pretty often when coming to stop or putting car in neutral....I thought it was a tune problem....

r3dn3ck · 03-27-2008, 09:12 AM

vacuum leak is also a possibility... listen for whistling sounds.

96gtstang · 03-27-2008, 11:01 AM

i originally thought it was a vaccumn leak but i figured a vaccumn leak would create a consistant problem rather than just once in a while maybe.

can somone get me the link to the TSB on the throttle cable deal or just let me know how to fix it (do you just somhow lube the cable?) and were talking about the cable that runs from the gas pedal to the throttle body not the springs on the throttle body right?

I cleaned the IAC today, if that seems to help i think i will just get a new IAC rather than have to clean this one every couple months or whatever.

00whtgt · 03-27-2008, 05:57 PM

Quote:

Originally Posted by B-rett

hmm this seems to happen to my car pretty often when coming to stop or putting car in neutral....I thought it was a tune problem....

I took mine off and cleaned it with some Throttle Body/Carb cleaner and it has worked like a charm ever since! You might want to try cleaning the MAF as well, the MAF and IAC get carbon build up and especially oil if you're running a K&N filter.

Scott

ponyexpress · 03-27-2008, 07:35 PM

try pushing on the connection on the tps and if that dosent do what your say bout that reving up n shit then try cleaning your throttle body and check where the cable come through the fire wall and mabey put a little dab of grease there

03-26-2008, 11:26 AM	#1 (permalink)
96gtstang Senior Member Join Date: Mar 2006 Location: cleveland, ohio Posts: 470	iac or tps my car is a 99 gt 5 speed- lately when getting off the highway or anytime im holding a certain speed/rpm for long period of time then take the car out of gear to slow down or whatever it revs up and stays up until i shut the car off and restart it. for example today i was goin down the highway at 2k rpm get to off ramp take it out of gear and the car just shoots up to 3k rpm and sticks, i reved it and it just stuck at the higher rpm i just reved to so i had to shut it off and restart, it just kept doing it the whole drive home and seems to be getting worse. I used to have this problem once every couple weeks but lately its more an more frequent. Im thinking its either the Throttle position sensor or the idle air control? what do you guys think

03-26-2008, 10:39 PM	#4 (permalink)
thebeastum Junior Member Join Date: Jul 2006 Location: inverness, fl Posts: 28	tps more than likely. when an iac motor goes bad it shuts of the motor. __________________ pypes x pipe mac cai flowmaster 40 series steeda tri ax mustangworld 70mm throttlebody bbk underdrive pullies

03-27-2008, 07:25 AM	#5 (permalink)
00whtgt Member Join Date: Feb 2008 Posts: 42	Sounds like the tps. I had my IAC screwing up and it would do the opposite, drop to real low rpm's and sometimes stall the car out. Scott __________________ Some Show: 17x9 Black Fr500 245/45 front 275/40 rear Steeda Sidewinder side sticker 3.5" Polished Tips 15% Tint Mach 1 chin spoiler Some Go: Motive 3.90's Steeda Tri-Ax Mac O/R H-pipe Flowmaster Catback Steeda Full Length Subframes

03-27-2008, 08:03 AM	#6 (permalink)
Randy Stinchcomb Super Moderator Join Date: Aug 2005 Location: Randallstown, Md Posts: 2,741	sounds like an IAC problem, thrttl cable sticking (which there was a TSB about the thrttle cable hanging-up at the carpet) or a vac leak........just an FYI: the TPS's used on the Modular cars since 1994 has been one of THE Most Trouble-Free TPS's ever used by FoMoCo, so I doubt your problem lies wth it....stock thrttlbdy or aftermarket? __________________ Randy Stinchcomb contact info: Liberty Ford of Baltimore 410-655-2000 parts ext 5618 like to fish visit us at www.sportfisherman.com need fishing tackle www.binnacletackle.com Last edited by Randy Stinchcomb : 03-27-2008 at 08:06 AM.

03-27-2008, 09:12 AM	#8 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,008	vacuum leak is also a possibility... listen for whistling sounds. __________________ Built 5.5L 2v and Maximum Motorsports Max Grip box. www.squarerootofone.com My CarDomain Page

03-26-2008, 02:44 PM	#2 (permalink)
96blackgt54 Senior Member Join Date: Aug 2007 Location: Lawrenceburg,KY Posts: 154	Go out and get it to do what it's doing and unplug one of them and note the diffrence. To me it sounds like a TPS. I've had the same problem with other cars and turned out to be the TPS.

03-26-2008, 09:41 PM	#3 (permalink)
96gtstang Senior Member Join Date: Mar 2006 Location: cleveland, ohio Posts: 470	yea im thinking its the tps as well but the reason i also have afeeling it could be the iac is because its like somthing is getting stuck open which makes the car want to just stay reved up with extra air and fuel, im thinking the valve on the iac might be stuck? anybody else got an idea

03-27-2008, 11:01 AM	#9 (permalink)
96gtstang Senior Member Join Date: Mar 2006 Location: cleveland, ohio Posts: 470	i originally thought it was a vaccumn leak but i figured a vaccumn leak would create a consistant problem rather than just once in a while maybe. can somone get me the link to the TSB on the throttle cable deal or just let me know how to fix it (do you just somhow lube the cable?) and were talking about the cable that runs from the gas pedal to the throttle body not the springs on the throttle body right? I cleaned the IAC today, if that seems to help i think i will just get a new IAC rather than have to clean this one every couple months or whatever.

03-27-2008, 07:35 PM	#11 (permalink)
ponyexpress Member Join Date: Nov 2007 Posts: 50	try pushing on the connection on the tps and if that dosent do what your say bout that reving up n shit then try cleaning your throttle body and check where the cable come through the fire wall and mabey put a little dab of grease there __________________

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