Racing engine after start

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Esteban - 15 Oct 2007 13:25 GMT

This squawk list came from my wife who has a '05 mustang V-8, 5 speed
tranny. The technicans at the local Ford Dealership read the codes two
months ago and said all was well.
If any of you have any suggestions, I would certainly appreciate hearing
about the issue.
Thanks,
Steve

Mustang squawk sheet:

Racing engine after starting. Drive 2-3 blocks then engine races
to 3000 rpms. Stop, put it in neutral and wait. After a minute or two, rpms
return to lower than usual idling speed, then up to 750, which is usual
idling speed.

First time I noticed this was in July; then three times since
then. The only time I notice it is shortly after starting the car.

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Frank ess - 15 Oct 2007 20:11 GMT

> This squawk list came from my wife who has a '05 mustang V-8, 5
> speed tranny. The technicans at the local Ford Dealership read the
[quoted text clipped - 14 lines]
> since then. The only time I notice it is shortly after starting the
> car.

You could check the TPS voltage (should be .98-1.01, they say)
TPS = Throttle Position Sensor
Part # DY967 (from motorcraft)

Or, you could try the "teach the throttle some manners" routine:

Engine off
Turn ignition to ON (do Not start)
Wait ten or a couple more seconds
Press the pedal all the way, HOLD ten or a couple more seconds
Release the throttle s-l-o-w-l-y
Turn ignition OFF
Wait ten or a couple more seconds before starting the engine.

This procedure is reputed to remove some lag from throttle response,
as well. Couldn't hurt, and it's free!

PS: Here's another version that's been going around:
Recalibration Procedure for Throttle:
Turn Key ON.
Wait for dash lights to go out.
Press throttle fully to floor quickly and release quickly.
Turn key OFF.

Let us know if it works.

Signature

Frank ess

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bob - 15 Oct 2007 23:16 GMT

>> This squawk list came from my wife who has a '05 mustang V-8, 5
>> speed tranny. The technicans at the local Ford Dealership read the
[quoted text clipped - 40 lines]
>
> Let us know if it works.

I never start the stang with the AC on, it tends to mess up the "learning"
for a while.

Wild a.s guesses;
Perhaps the air bypass is dirty ?
Or Throttle cable is sticky ??
Could have a bad spot in the TPS ???

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Jim Warman - 16 Oct 2007 04:19 GMT

With this throttle by wire system, the place to start is going to be
scanning for codes and perhaps running the KOER On Demand test... Much can
happen in the two months since codes were checked in the car and this is
going to have to be one of the early steps to try and eliminate any
guesswork.... There are many concerns that will not turn on either the
wrench light or the MIL....

Without knowing where you live or the prevailing weather conditions, there
is even the chance that ice may be forming around the throttle plate. The
actuator should be strong enough to break any ice but....... If icing is the
cause, you *might* expect a P2072 or a P2111.

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Thomas Hart - 16 Oct 2007 10:28 GMT

>This squawk list came from my wife who has a '05 mustang V-8, 5 speed
>tranny. The technicans at the local Ford Dealership read the codes two
[quoted text clipped - 13 lines]
> First time I noticed this was in July; then three times since
>then. The only time I notice it is shortly after starting the car.

FWIW, I have an '06 V6 Mustang that's had this problem since it was new,
yet the dealership keeps telling me they can't reproduce the failure. Mine
only races up to about 2500 or so, but exactly like yours, will drop down
to 7-800RPMs or so when I reach a stop (I don't have to wait a minute for
this though - only about 2 or 3 seconds). I've since learned to work
around the problem by re-starting the engine after five minutes of
running. Kinda sucks having to do this, though... Initially, I was hoping
a custom tune from Bamachips would fix the problem, but it didn't seem to
make any difference.

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Esteban - 16 Oct 2007 23:26 GMT

>>This squawk list came from my wife who has a '05 mustang V-8, 5 speed
>>tranny. The technicans at the local Ford Dealership read the codes two
[quoted text clipped - 25 lines]
> a custom tune from Bamachips would fix the problem, but it didn't seem to
> make any difference.

Hi folks,
First, thanks to all who responded
I was able to get an appointment at the local Ford, Merc. Dealership this
afternoon. I have the utmost faith in their shop, the tech's that I have
met all seem very professional and knowledgable. The Service Writer told me
all the codes check fine. His suggestion was to keep using the vehicle
until it gets much worse, and to leave the airconditioning switch in the off
position until the car is started. I really symphonize with the tech's when
they must waste their time with a intermittent problem.
For Jim: I live in Rogers, AR. hot and humid in the summer, other times of
the year we still have the humidity, but the temps are tolerable. Having
worked in General Aviation all my life, I appreciate your concern about
"Carb Ice"
Once again, thanks to all.
Steve

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