High Idle On Startups
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High Idle On Startups
Aside from changing my oil, I'm not much of a mechanic. Can anyone suggest where to start troubleshooting this; I have a 99 F150. 4.2liter V6, 5 speed.
Sometimes it sounds like the engine is going to rev through the hood when I start it. It only lasts for about 5 or 6 seconds and then comes down to normal. It doesn't happen all the time, usually after it sits for an hour or two.
Thanks for any help.
Sometimes it sounds like the engine is going to rev through the hood when I start it. It only lasts for about 5 or 6 seconds and then comes down to normal. It doesn't happen all the time, usually after it sits for an hour or two.
Thanks for any help.
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Joined: Jun 2003
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Has a code been put out yet? Sounds like a faulty TPS (Throttle Position Sensor).I would ck there first,if you have a faulty TPS it could cause intermittent fuel burst, end result is unstable idle. Hope this helps.
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Joined: Dec 2001
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From: Louisville,Ky.
Hi and welcome to FTE 
Does it have a tach? If so, what is the actual rpm?
It is normal for them to idle fast when first started cold.
You may just have a lazy IAC (Idle Air Control). This is common on engines with some miles on them. You could try cleaning it, but it is best to just replace it.
It is located on the throttlebody and is held on by 2 8mm bolts and has a 2 wire connector on it.
Jimmy
Does it have a tach? If so, what is the actual rpm?
It is normal for them to idle fast when first started cold.
You may just have a lazy IAC (Idle Air Control). This is common on engines with some miles on them. You could try cleaning it, but it is best to just replace it.
It is located on the throttlebody and is held on by 2 8mm bolts and has a 2 wire connector on it.
Jimmy
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Wow, thanks for the quick responses.
I don't have a tach, but I wish I did. There is a definite difference between the normal high idle and the extreme high idle. It's wierd because the truck can sit for a day or two and start fine, but sitting just a couple of hours and then starting produces the extreme high idle.
No computer codes.
I will check on the TPS. A co-worker of mine had mentioned that as well. I also look at the IAC.
Do you think it may be worth having a shop hook it up to a diag machine, or should I just change the TPS?
Thanks again.
I don't have a tach, but I wish I did. There is a definite difference between the normal high idle and the extreme high idle. It's wierd because the truck can sit for a day or two and start fine, but sitting just a couple of hours and then starting produces the extreme high idle.
No computer codes.
I will check on the TPS. A co-worker of mine had mentioned that as well. I also look at the IAC.
Do you think it may be worth having a shop hook it up to a diag machine, or should I just change the TPS?
Thanks again.
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IAC Worked....but
I may be making progress, but may have caused a new problem. I replaced the IAC and gaskette. I think the reving problem is gone, but now there is an intermittent "whistle" or "whiirrr" sound coming from the throttle body location. Logically I should probably put the old IAC back on and see if that problem goes away, but I was wondering if maybe the new IAC has to break in, or, perhaps it's working so good that a different, unrelated problem has reared it's head.
Any thoughts?
Any thoughts?
