Hard start

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Dec 15, 2004 | 01:25 PM

fordman311

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Hard start

I got '97 f150 4.6L V8 and its been startin pretty hard lately. It's hard to start and keep it goin, tends to stall out unless I hit gas and let off b4 it chokes out engine then hit gas again and hold it for a while to keep up RPM's til it warms up some, its been gettin down to 30 degrees, upper 20's. Is it normal for this engine to do this because of the cold, if not tell me what to check out plz.

Dec 15, 2004 | 01:38 PM

BillyBob69

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From: Wheatland, Mo

That sounds like its the IAC (Idle Air Control) valve. They can be cleaned and help smooth out the idle a bit, but yours sounds like it needs to be replaced. Takes about 5 minutes and nothing more than a couple of sockets. They usually run about $60 to $80 depending on where you get it from. It is located on the top/back of your intake manifold. Remove the plastic cover over the manifold, then you will see it on the top at the back. It has a 2 or 3 wire harness plugged into it and it is held down with 2 bolts. Quick and easy.

Dec 15, 2004 | 02:36 PM

fordman311

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thanks man ill check it out

Dec 15, 2004 | 07:01 PM

fordman311

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I thought i had just replaced the IAC but didnt want to say anythin til i was sure, and I checked the records and it turns out i had a new one put in at the end of this past september. Any other guesses as to what it could be?

Dec 16, 2004 | 08:06 AM

Tom

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From: Isanti, MN

Maybe the new one is defective. The IAC is what controlls the idle speed of the engine. When the throttle plate is closed, the only source of air for the engine is through the IAC. Increasing the flow through this increases the idle speed when the engine is cold.

It may also be worth a check to see if the IAC is recieving the proper signal from the PCM. You can check the terminals of the wires connected to the IAC with the ignition on, and there should be 10.5-12.5 volts. If incorrect, there may be a short somewhere. You can also check the resistance of the IAC terminals and there should be 6.0-13.0 ohms between the terminals. If the resistance isn't between these values, the IAC valve is defective.

Dec 22, 2004 | 08:22 AM

fordman311

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I was going to check the readings on all that stuff this morning, took of the plastic cover, and the sensor a good bit of mud splatter on it prob about 40% of the sensor surface. So is there anything special anbody recommends to clean the sensor and any warnings or special stuff to do for cleaning.

Dec 22, 2004 | 08:31 AM

Kevdadi

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I would recommend some throttle body spray. I've heard before that the carb cleaner is "more harsh" or sensor unfriendly than the throttle body spray. If you ask me, it's just marketing.

MY QUESTION TO YOU GENTLEMEN IS:
I live in Michigan, it's been getting down into the single digits + wind chill = sub zero temps. My 5.4L has had a hard time starting cold during these days; any other time its a breeze. I keep the tank at least 1/2 full (expensive as that may be) so the gas doesn't freeze too. DO YOUR TRUCKS HAVE A HARD TIME STARTING IN COLD WEATHER? I HAVE TO KEEP FEEDING IT GAS FOR LIKE 20-30 SECONDS SO IT DOESN'T STALL.