5.4 with strange startup
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Joined: Jul 2001
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From: Walterboro, SC
5.4 with strange startup
My Dad took his truck into Ford last week because he said it was running rough or something. (No engine light) Ford scanned it and came up with nothing. Of course, they don't actually want to check into the problem so they sent it off saying it was fine. I had to use his truck to go to town today and noticed that the startup and idling is messed up.
If you start it up without the A/C on it will rev up to ~1000 then fall to about 250-300 and barely cough itself back up to 500 or so then fall again and come up to 550 and stay there. It didn't used to idle this low (usually around 650-750) I can tell that it is idling too low because it sounds rough. The funny thing is that if you switch the A/C ON before starting it does just fine and idles at 700!?? What gives?
His truck is a 1999 F-250 XLT, 5.4, Auto, 3.73
If you start it up without the A/C on it will rev up to ~1000 then fall to about 250-300 and barely cough itself back up to 500 or so then fall again and come up to 550 and stay there. It didn't used to idle this low (usually around 650-750) I can tell that it is idling too low because it sounds rough. The funny thing is that if you switch the A/C ON before starting it does just fine and idles at 700!?? What gives?
His truck is a 1999 F-250 XLT, 5.4, Auto, 3.73
Last edited by nothingbutford; Jul 3, 2004 at 11:34 PM. Reason: Oops, forgot to tell you what truck it is.
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Joined: Nov 2003
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From: Allen, Tx
I bet the IAC is just about dead. The Idle Air Control motor is bolted to the rear of the throttle body, facing the firewall. It's held in by 2 9mm bolts or maybe it was 10mm, I forgot. They are $54 at NAPA, or $96 at the Ford dealer. These are local prices from 6 months ago when I replaced one on a friend's 5.4L of the same vintage. He prefered a "real" Ford part, can't say I blame him.
Last edited by n578md; Jul 4, 2004 at 12:08 AM.
Thread Starter
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Senior User
Joined: Jul 2001
Posts: 491
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From: Walterboro, SC
I don't know why I didn't think of the IAC! I've read pleanty of posts on here about that problem. Well, thanks for your responces! Now the question is wether I should clean it or replace it?
Happy 4th to you also!
Happy 4th to you also!
