1993 Ford F350 High Idle

GLOBAL WELD

MEMBER
1993 FORD F-350
V8
2WD
AUTOMATIC
120,000 MILES

Hi. I am having trouble with my truck. It has a higher idle than normal. It runs fine and doesn't miss. I put on a new air idle control. But it still has a high idle. It hesitates between 45-50. Seems like it is running out of gas. But when I let off the gas it comes back to normal. It has a new fuel filter. The in tank gas pumps were replaced about a year ago. It almost seems like it chokes itself out. If I leave my foot on the gas pedal, it seems like it would die. But if I let off the gas it runs again. I tried a new map sensor but that didn't help. Any help would be appreciated.

Friday, February 13th, 2009 AT 6:35 PM

5 Replies

BILLYMAC

MECHANIC
2,204 POSTS

Hi could be the throttle position sensor or a intake leak. Both of these are common for this truck. Good luck billymac

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Friday, February 13th, 2009 AT 6:44 PM

BILLYMAC

MECHANIC
2,204 POSTS

HI TY FOR THE APPRICIATION. NOT SURE WHAT IS WRONG, BUT YOU SHOULD BE ABLE TO VOTE IF NOT PLEASE CONTACT MADERATOR THANKS BILLYMAC

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Friday, February 13th, 2009 AT 10:04 PM

TOMPOND

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I have the exact same problem with my 1995 5.8. I repalced the iac and it did not help. If I unplug the iac, the idle slows to 1000rpm. When I reconnect it, it runs 2300rpm. I check for vacuum leaks by spraying starting fluid on all lines. When I mash the accelarater it falls on its face like it is out of gas but if I let off and down shift it regains power. I can drive it 100mph if I just ease in to it. Any help would be much appreciated. It has been in and out of 3 ford garages and they could not fix it, it has sat in my garage for 1.5 years since I cant fix it.

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Tuesday, March 24th, 2009 AT 7:02 PM

TOMPOND

MEMBER
3 POSTS

I forgot to mention that I unpluged the temp sensor to see if the pcm thought the engine temp was high or low causing high idle to cool or high idle to warm up.

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Tuesday, March 24th, 2009 AT 7:24 PM

TOMPOND

MEMBER
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Problem fixed! I changed the throttle position senser $35 and the coolant temp senser $35. I changed the gasget on the throttle body when I had it off to change the tps. My theory is the pms thought the engine was hot and caused the iac to open to idle the engine up to cool it down. I would assume if you had a bad thermostat and the engine really was hot you would have a high idle too.

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