V-10 Starting Problem

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Jul 25, 2005 | 09:28 AM

PeteC

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V-10 Starting Problem

Yesterday the engine would turn over, barely catch and then die. Same thing over and over.

Later I tried again and this time I pressed the gas pedal a little and it started but died again. After a couple more tries with a little gas pedal it started and kept running. After it warmed up for a minute I shut it off and it started fine (without having to press the gas pedal).

Same thing this morning; a little gas pedal to start it after a couple tries. Drove to work. Starts fine after warmed up.

Any idea what is going on here?

Thanks

99 F350 V-10, Auto, LWB 2WD

Jul 25, 2005 | 09:39 AM

n578md

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From: Allen, Tx

IAC (Idle Air Control) motor has died or the valve in it is dirty and no longer opens and closes. Probably easier just to replace it. 64 bones at Napa.

Jul 25, 2005 | 10:16 AM

PeteC

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Would the valve or motor failing show up in an error code?

Jul 25, 2005 | 10:19 AM

n578md

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From: Allen, Tx

Sometimes it does. You can get a P0505 which indicates an IAC failure.

Jul 25, 2005 | 10:42 AM

PaulC

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The motors behavior while the throttle is pressed is the giveaway to an IAC issue. The IAC modulates air into the engine while the throttle plate is closed. When you press the accelerator pedal, the throttle plate is opened, taking the IAC out of the picture. Like n578md said, sometimes you get a code.

Jul 26, 2005 | 02:44 PM

PeteC

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How hard is it to change the IAC valve?

Jul 26, 2005 | 06:02 PM

PaulC

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Accessing the valve is usually the biggest pain on the whole process. The valve is held in place with two small bolts and has a pair of wires running from it. Unplug the harness, unscrew the bolts, remove the IAC and it's diamond-shaped paper gasket. Install a new gasket, bolt up the IAC, plug the wiring harness back up.
It's also a good idea to remove the negative battery cable from the battery before you begin. You want to force the engine management system into it's learning mode in order for it to become acquainted with the new IAC. The last step should be to screw the cable back on.