Engine idles high..
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Engine idles high..
I have an 89 F-250 351 5-speed that occasionally more often than wanted just wants to idle at 2000 or more rpms. No matter if I let it warm up in the driveway in the morning or if its cold. I found out I can get rid of the high idle by stomping on the gas quick to the floor and it will drop the idle back to it's normal 6-700 rpm. As soon as you touch the gas again though it will jump right back up to a high idle. Same thing, stomp it to the floor it comes back down. I really don't get it. And then sometimes it runs just perfect with no idle jump. Any ideas?
It's got a TQ cam, long tubes, dual exhaust, EGR removed, electric fan conversion, all new gaskets, rebuilt, ported heads.
It's got a TQ cam, long tubes, dual exhaust, EGR removed, electric fan conversion, all new gaskets, rebuilt, ported heads.
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Joined: Oct 2007
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Originally Posted by dj250
I have an 89 F-250 351 5-speed that occasionally more often than wanted just wants to idle at 2000 or more rpms. No matter if I let it warm up in the driveway in the morning or if its cold. I found out I can get rid of the high idle by stomping on the gas quick to the floor and it will drop the idle back to it's normal 6-700 rpm. As soon as you touch the gas again though it will jump right back up to a high idle. Same thing, stomp it to the floor it comes back down. I really don't get it. And then sometimes it runs just perfect with no idle jump. Any ideas?
It's got a TQ cam, long tubes, dual exhaust, EGR removed, electric fan conversion, all new gaskets, rebuilt, ported heads.
It's got a TQ cam, long tubes, dual exhaust, EGR removed, electric fan conversion, all new gaskets, rebuilt, ported heads.
Sounds like its failing
I don't rememeber the colour code right now, but you can probe the three wires @ the connector and figure it out with a DVOM
5.0 Vdc reference
Closed Throttle should be around 0.901 Vdc
Full Throttle around 4.538 Vdc
Freshman User
Joined: Oct 2007
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Originally Posted by dj250
Yeah I put a new TPS in already, forgot to mention that. Along with a new oxygen sensor. But it will not idle high untill you touch the gas, so it's weird.
On 5.0L and 5.8L engines, position the TP sensor so that the pigtail points toward the IAC valve...
Check that first, then the voltages before you go any further...
Last edited by airmetdave; Oct 27, 2007 at 08:23 PM.
Cross-Country
Joined: Jan 2003
Posts: 65
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From: Winthrop Harbor, IL
Wonder if it's the throttle valve itself sticking inside the housing??? I would pop the linkage off, with the truck not running, and work the throttle by hand a few times just to make sure. Can't hurt, right? Maybe it's just starting to hang up and the springs aren't returning the blades all the way back every time. Just had this happened to me at work on an EFI Bronco that had sat for awhile. Apparently there was just enough oxy in there to hang things up... a little WD40 and the valve is working again. Can't hurt to check this out just to make sure.
Last edited by Adam79; Oct 28, 2007 at 08:36 AM.
