Unusual Idle problem
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New User
Joined: Mar 2004
Posts: 7
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From: Texas
Unusual Idle problem
I have a 1998 F-150 with a 4.6 L. As I come to a stop, the engine RPM continues dropping beyond the normal idle to around 200 RPM and occasionally the engine will stall. Hard braking seems to aggravate the problem. I've had this truck into the Ford dealer several times. Replace Idle air control valve, etc. Full emissions service and vacuum leak check. Any thoughts.
Thanks,
BJ
Thanks,
BJ
Cargo Master
Joined: Aug 2002
Posts: 2,013
Likes: 6
From: Cajun Country
I had a 93 F150,302, that did the same thing you described.After throwing all kinds of parts at it, I finally took it to Ford.They replaced the fuel pressure regulator and fixed the problem! 
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Hi BJ and welcome to FTE
If you take it in to get the fuel pressure tested you might also get them to check and see if there are any updates for the PCM programming. I think there might be something in the calibration to fix this.
If you take it in to get the fuel pressure tested you might also get them to check and see if there are any updates for the PCM programming. I think there might be something in the calibration to fix this.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Yes but it might also cause a hard brake pedal. With the engine off let the truck sit a few minutes and then try the brakes. If it feels like there is still power brakes then you probably dont have a leaking diaphragm.
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