I've got a 92 F150 with the 351. It's got almost 214K on it now and in the past couple of months it's developed a surge while at idle. It's a two wheel drive, with A/C and it's an automatic.

I first noticed it ie early winter. I'd go out and start it to let it warm before my 10 minute drive to the office. After a few minutes, the high idle would kick off and the motor starts to surge. I get in and it drives normally. At a light sometimes it'll surge, sometimes it doesn't. Once or twice at barely moving speed, if I turn the wheel sharply, it'll die. I throw it in N and it restarts with no problem.

I change the oil every 3K as I should and it's been a great truck. I bought it used in 96 with about 24K on it. At that time I was in the military so we put alot of highway miles on it. No motor problems...I've maintained the truck well as evidenced by it's longevity.

Does anyone have any suggestions? I'm NOT a mechanic...just a truck owner that's done basic maintenance myself.

Thanks!

 

What RPMs are you turning at an idle when it is surging?

 

At idle it's a little less than a grand....and then it drops to about half that and then surges back up again.

BTW, I'm jealous! I've been watching Ford since they started talking about competing for the Chevy Suburban market. I thought the concept was fantastic and kept playing the lottery (LOL!) so I could afford one. You have the (IMO) one of the original concept vehicles! Nice ride!

 

Could this be related to a bad IAC? Gunked up throttle body? Not really sure.

Thanks for the compliment, I love my truck. Seems like people never stop complimenting it

-Chris

 

take off the AIC and hit it with carb cleaner.

 

Ok, what's the AIC? I've had my local mechanic listen to the motor and he says he's exhausted his knowledge. His recommendation was to start replacing parts...trial and error.

My gut tells me that's gonna be an expensive proposition for the truck. It would be different if it only had 100K on it.

Like I said earlier, it's still drivable...I took it to work this morning and it runs fine...it's just at idle and I know that something needs attention...I just don't know what.

 

Idle control valve is whare I would start. I had the same problem with my 88. ON the TB there is a small unit looks like a small motor. Right at the butterflys. 2 screws hold it on. Take it off and clean the inside with carb cleaner.