99GT won't run at idle

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Randy Replogle - 23 Oct 2006 17:37 GMT

I went to drive my son's 99 GT last night. It started but died when I
let off of the accelerator. It ran as long as I gave it some gas,
however. After some time of holding the pedal down and warming up, it
would idle for a short while at slow rpms then die. Is a sensor of some
type going out or is something dirty? It was a cold day. Thanks,
Randy

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Anabaena Microcystis - 23 Oct 2006 18:21 GMT

>I went to drive my son's 99 GT last night. It started but died when I let
>off of the accelerator. It ran as long as I gave it some gas, however.
>After some time of holding the pedal down and warming up, it would idle for
>a short while at slow rpms then die. Is a sensor of some type going out or
>is something dirty? It was a cold day. Thanks,
> Randy

The air idle bypass needs cleaning with carb clean, EZ. done it several
times.
looks like this bolted to the throttle body on the front

http://fordfuelinjection.com/?p=11

They get gooked up with crud/oil

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Randy Replogle - 23 Oct 2006 19:44 GMT

>> I went to drive my son's 99 GT last night. It started but died when I let
>> off of the accelerator. It ran as long as I gave it some gas, however.
[quoted text clipped - 10 lines]
>
> They get gooked up with crud/oil

Thanks a lot! I'll look for it tonight.
Randy

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wabbitslayer - 24 Oct 2006 00:49 GMT

it's the IAC valve

http://www.moddedmustangs.com/cleaning-your-iac.html

the first pic shows a 4.6, which doesn't really give you a reference; (the
second is a 5.0) but it's right up top, on front. will take you a grand
total of maybe 5 minutes to take it off and 5 more to put it back on,
although you'll have to get the bottom bolt back in by feel, you can't see
it. Although.... mine has acted up several times, and I 've taken it off and
sprayed it each time. A mechanic friend says cleaning is pointless, will
work for a little bit and act up again. After cleaning mine several times, I
think I agree. Next time I'll spend the 50 bucks or so and get another one.

wabbitslayer
01 GT vert

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Randy Replogle - 24 Oct 2006 17:13 GMT

> it's the IAC valve
>
[quoted text clipped - 11 lines]
> wabbitslayer
> 01 GT vert

I didn't remove it, just took the tubing off and sprayed into the hole.
after awhile it worked fine. Guess I should take it off and do it right
next warm day. We're expecting snow showers this week. :( Have you
ever known a mechanic to *not* recommend a *new* part?
Randy

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Brent P - 24 Oct 2006 21:46 GMT

>> it. Although.... mine has acted up several times, and I 've taken it off and
>> sprayed it each time. A mechanic friend says cleaning is pointless, will
>> work for a little bit and act up again. After cleaning mine several times, I
>> think I agree. Next time I'll spend the 50 bucks or so and get another one.

> I didn't remove it, just took the tubing off and sprayed into the hole.
> after awhile it worked fine. Guess I should take it off and do it right
> next warm day. We're expecting snow showers this week. :( Have you
> ever known a mechanic to *not* recommend a *new* part?

YMMV but, I cleaned the IAC valve once a couple years ago. Then again, on
my grandmother's car, cleaning only worked for a little bit. Given my
experience with the purge valve, it depends on why it's acting up. If the
solinoid is going, then cleaning won't last long. Cleaning it only takes
enough resistance away so it works again, but it's still weaker than it
should be and will get weaker yet. If it's because it's just grime and
the solinoid is still good, then cleaning will work.

So what I do with parts like this is I clean them at first, I will
continue cleaning them so long as the cleaning is infrequent. (as in once
a year or less) If it's every few weeks, then it's time to replace.

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