88 5.0 having running problems. fast idle

8

85cleangtvert

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#1

• Sep 29, 2005

• #1

i have been driving my 88 5.0 for a while and it was running fine. I went to start it the other day and it was idling over 2000 rpms, when usually its around 1000 and runs normal. i checked out the engine and i cant find anything wrong. we checked the timing and it was fine. anyone know what this could be? just out of no where? also my cold air induction sounds like it is sucking a lot more air than it used to. when i turn off the car i can still hear it for a sec., when before i never hear this. any ideas??

 

darthcual

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#2

• Sep 29, 2005

• #2

It sounds like the tps to me. Check the voltage.

 

8

85cleangtvert

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#3

• Sep 29, 2005

• #3

whats the tps supposed to be at?

 

jrichker

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#4

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See the stick "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems.

 

HISSIN50

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Also look at big hoses (like the brake booster) in case it came off or cracked. A huge vac leak can create an idle like you have.
A vac leak will create a huge sucking noise.

Good luck.

 

90mustangGT

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#6

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HISSIN50 said:

...A vac leak will create a huge sucking noise.

Good luck.

Click to expand...

Don't you mean usually? Like JT said, brake boosters and such can leak as well, but you might not hear them.

First, check the codes. Take advantage of the complex rats nest of wires and sensors. If codes are clear, I would first check to be sure the throttle cable is not binding or sticking. Checking TPS voltage is another point, the signal wire should only put out .99 volts at idle. Ford IAC motors are bad about being "almost bad" and giving all kinds of problems but not showing codes. A vacuum leak is a likley spot, but don't forget to check around the upper to lower intake gasket, TB gaskets, as well as lower intake gaskets.

 

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85cleangtvert

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#7

• Sep 29, 2005

• #7

my brother and i are looking at the car right now and it is sucking alot of air through the cold air intake. the idle is high still. what should i set the timing to? i have a e 303 cam/ gt 40 heads /edlebrock intake. i am going to check the tps sensor right now.

 

8

85cleangtvert

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#8

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• #8

we set the timing to about 10*, adjusted the tps as close as we could get it to specs. cleaning the iac made the most difference. The car idled normal after I cleaned it out. It didnt look that bad but I guess it makes the difference. as I was making some adjustments I dropped my screwdriver and when I looked under the car I noticed the cats were glowing orange/red. I have the stock h pipe, so actually it was the first two cats, not the back ones. also, now that I think about it, it has been feeling a little restricted and i remember my old iroc had a glowing red cat and that was causing problems. I am guessing I should replace them or get a different pipe, but I still want it to be smog legal. what do you guys think?

 

HISSIN50

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90mustangGT said:

Don't you mean usually? Like JT said, brake boosters and such can leak as well, but you might not hear them.

Click to expand...

Nice catch - I got my wires crossed. I said:

...A vac leak will create a huge sucking noise.

And I meant to say:

...A huge vac leak will create a sucking noise.

 

jrichker

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#10

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HISSIN50 said:

Nice catch - I got my wires crossed. I said:

...A vac leak will create a huge sucking noise.

And I meant to say:

...A huge vac leak will create a sucking noise.

Click to expand...

Is that anything like the sound I hear coming from my wallet when I fill the gas tank?

 

HISSIN50

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#11

• Sep 30, 2005

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jrichker said:

Is that anything like the sound I hear coming from my wallet when I fill the gas tank?

Click to expand...

JR, were we in person, I have a couple one liners involving this whole subject (as I am sure you might), but I wont digress.

Last time I filled up, I think I left a pound of flesh behind.