Idle Too High

terribleonexx88 · October 14th, 2006, 06:40 PM

88 mustang lx 5-speed. it idles at 1500rpm the i was told from many sources its the idle air control unit. i just bought one at pepboys and put it on it still idles at 1500rpm but when i unplug the electrical connecter attached to the unit it idles right at a grand. somebody help me.

thanks
nick

Screemin3o2 · October 14th, 2006, 07:32 PM

put a t/b or anything on it lately? Check your idle screw. The service data calls for my year to idle at 680RPM

terribleonexx88 · October 14th, 2006, 08:55 PM

nope everything is stock as far as i know but its weird when i unplug the connecter it goes down to 1000 also some of the vaccum lines are half assed could that do anything to the idle?

nick

TENGRAM · October 14th, 2006, 09:01 PM

Originally Posted by terribleonexx88

nope everything is stock as far as i know but its weird when i unplug the connecter it goes down to 1000 also some of the vaccum lines are half assed could that do anything to the idle?

nick

if the vacuum lines are leaking, yes it'll cause your idle to be too high and often will cause a lopey idle, but i agree with Screemin3o2 that you probably just need to adjust your idle screw on the TB. idle with the IAC unplugged should be ~650-700

terribleonexx88 · October 14th, 2006, 09:31 PM

thanks guys ill check it out 2morro

nick

Screemin3o2 · October 14th, 2006, 09:48 PM

did this all of the sudden start doing this?

terribleonexx88 · October 14th, 2006, 10:18 PM

ive only had the car for about two weeks but seller told me about the idle issue it before i bought it. when i got the car the idle went up and down unless the iac was disconnected but i noticed the coolant lines to the egr were bypassed with a copper tube(the gasket needed to be replaced so the former owner bypassed it instead of replacing the gasket) so i reconnected the two lines(and put a new gasket in). the idle was now steady, but at 1500rpm.

matrixpuba · October 14th, 2006, 10:29 PM

did you check tps voltage at idle? what is it?

terribleonexx88 · October 14th, 2006, 11:48 PM

no i didnt check that, what should it read

TENGRAM · October 15th, 2006, 12:03 AM

Originally Posted by terribleonexx88

no i didnt check that, what should it read

technically .49-1.20vdc. to be safe i would make sure its between .80-1.00vdc

internet myth will say .98vdc, but its BS, since the ecm "zeros" out the base (closed TB) voltage at start-up and change representing part-throttle and WOT is determined by an amount added to that base, rather than a pre-determined voltage.

i just woke up, so that may not be too clear, for more info check out This Article on EEC mythology.
specifically post #2 (mythology case #1)

terribleonexx88 · October 15th, 2006, 12:14 AM

nothing ever has a simple solution ....

TENGRAM · October 15th, 2006, 12:43 AM

Originally Posted by terribleonexx88

nothing ever has a simple solution ....

your not kidding...believe me i've done alot of experimenting with it, just make sure it is between .80 volts and 1.0 volts and it will be perfect. the voltage should be checked between the green and black wires, and can be checked with the key on (where you hear the fuel pump prime) and engine off.

shadowgames81 · October 15th, 2006, 12:45 AM

I had the same problem problem on my 91 and I was told bout a spacer between the aic and throttle body and I put it on and fixed all my probs not sure if its gonna help but it was like 9 bux s it was a cheap fix no hurt to try

terribleonexx88 · October 15th, 2006, 12:58 AM

how thick of a spacer?

Bill · October 15th, 2006, 01:07 AM

i need to get a new TPS tomorrow. im getting a code 63. saying TPS below .6 volts. piece broke that tells the computer how much gas your giving. and im getting a code 98 because of it. PCM running in Failure Effects Management Mode

TENGRAM · October 15th, 2006, 01:18 AM

Originally Posted by Bill

i need to get a new TPS tomorrow. im getting a code 63. saying TPS below .6 volts. piece broke that tells the computer how much gas your giving. and im getting a code 98 because of it. PCM running in Failure Effects Management Mode

BTDT, runs like ass in limp mode don't it? let us know if the new TPS doesn't fix it, we'll see what we can do

shadowgames81 · October 15th, 2006, 01:54 AM

it was like a 1/4 in spacer an I actually bought it from the ford shop here in NN, VA an it stopped my idle probs and cost like 9 or 10 bux. not sure what they called it prolly somethin simple like iac spacer. my boy made one from alum himself and shaped an drilled holes and seemed 2 fix his idle probs 2 man

91GRNGT · October 15th, 2006, 11:42 AM

there is a spacer??? my idle is constant at 850 or maybe 900, is this too much?? I figured it wasn't past a g so why not lol

TENGRAM · October 15th, 2006, 01:24 PM

Originally Posted by 91GRNGT

there is a spacer??? my idle is constant at 850 or maybe 900, is this too much?? I figured it wasn't past a g so why not lol

technically, idle should be 650-700rpm, but if your idle is steady i wouldn't mess with it.

91GRNGT · October 15th, 2006, 01:34 PM

yes my idle is steady, Some times I guess it does do 700 it is a nice idle though.. wont mess with that..

October 14th, 2006, 08:55 PM	#3
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	nope everything is stock as far as i know but its weird when i unplug the connecter it goes down to 1000 also some of the vaccum lines are half assed could that do anything to the idle? nick __________________ 85 svo. work in progress

October 14th, 2006, 09:31 PM	#5
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	thanks guys ill check it out 2morro nick __________________ 85 svo. work in progress

October 14th, 2006, 09:48 PM	#6
Screemin3o2 Enthusiast Join Date: Jun 2006 Location: Knoxville, TN Posts: 616 iTrader: 0 reviews	did this all of the sudden start doing this? __________________ 95 Mustang GT Slow Bolt On Car www.steelcitystangs.com

October 14th, 2006, 10:18 PM	#7
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	ive only had the car for about two weeks but seller told me about the idle issue it before i bought it. when i got the car the idle went up and down unless the iac was disconnected but i noticed the coolant lines to the egr were bypassed with a copper tube(the gasket needed to be replaced so the former owner bypassed it instead of replacing the gasket) so i reconnected the two lines(and put a new gasket in). the idle was now steady, but at 1500rpm. __________________ 85 svo. work in progress

October 14th, 2006, 10:29 PM	#8
matrixpuba Hardcore Enthusiast Join Date: Sep 2006 Location: tennessee Posts: 2,364 iTrader: 0 reviews	did you check tps voltage at idle? what is it? __________________

October 14th, 2006, 06:40 PM	#1
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	Idle Too High 88 mustang lx 5-speed. it idles at 1500rpm the i was told from many sources its the idle air control unit. i just bought one at pepboys and put it on it still idles at 1500rpm but when i unplug the electrical connecter attached to the unit it idles right at a grand. somebody help me. thanks nick

October 14th, 2006, 07:32 PM	#2
Screemin3o2 Enthusiast Join Date: Jun 2006 Location: Knoxville, TN Posts: 616 iTrader: 0 reviews	put a t/b or anything on it lately? Check your idle screw. The service data calls for my year to idle at 680RPM __________________ 95 Mustang GT Slow Bolt On Car www.steelcitystangs.com

October 14th, 2006, 11:48 PM	#9
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	no i didnt check that, what should it read __________________ 85 svo. work in progress

October 15th, 2006, 12:14 AM	#11
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	nothing ever has a simple solution .... __________________ 85 svo. work in progress

October 15th, 2006, 12:45 AM	#13
shadowgames81 Hardcore Enthusiast 87 Coupe Join Date: Sep 2006 Location: Hampton, VA Posts: 1,220 iTrader: 3 reviews	I had the same problem problem on my 91 and I was told bout a spacer between the aic and throttle body and I put it on and fixed all my probs not sure if its gonna help but it was like 9 bux s it was a cheap fix no hurt to try

October 15th, 2006, 12:58 AM	#14
terribleonexx88 Enthusiast Join Date: Oct 2006 Location: new england Posts: 822 iTrader: 0 reviews	how thick of a spacer? __________________ 85 svo. work in progress

October 15th, 2006, 01:07 AM	#15
Bill Hardcore Enthusiast Join Date: Aug 2005 Posts: 1,327 iTrader: 0 reviews	i need to get a new TPS tomorrow. im getting a code 63. saying TPS below .6 volts. piece broke that tells the computer how much gas your giving. and im getting a code 98 because of it. PCM running in Failure Effects Management Mode __________________ Too often, We lose sight of life's simple pleasures. Remember, when someone annoys you it takes 42 muscles in your face to frown, BUT, it only take 4 muscles to extend your arm and bitch-slap that Mother@#?!&! upside the head!!

October 15th, 2006, 01:54 AM	#17
shadowgames81 Hardcore Enthusiast 87 Coupe Join Date: Sep 2006 Location: Hampton, VA Posts: 1,220 iTrader: 3 reviews	it was like a 1/4 in spacer an I actually bought it from the ford shop here in NN, VA an it stopped my idle probs and cost like 9 or 10 bux. not sure what they called it prolly somethin simple like iac spacer. my boy made one from alum himself and shaped an drilled holes and seemed 2 fix his idle probs 2 man

October 15th, 2006, 11:42 AM	#18
91GRNGT Regular Join Date: Oct 2006 Location: Cohutta,ga Posts: 117 iTrader: 0 reviews	there is a spacer??? my idle is constant at 850 or maybe 900, is this too much?? I figured it wasn't past a g so why not lol __________________ 1991 Mustang GT 306, with KB .30 over pistons, steeda #18 cam! 05 Dodge Neon "Daily driver" Does dodge and ford match???

October 15th, 2006, 01:34 PM	#20
91GRNGT Regular Join Date: Oct 2006 Location: Cohutta,ga Posts: 117 iTrader: 0 reviews	yes my idle is steady, Some times I guess it does do 700 it is a nice idle though.. wont mess with that.. __________________ 1991 Mustang GT 306, with KB .30 over pistons, steeda #18 cam! 05 Dodge Neon "Daily driver" Does dodge and ford match???

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