My 1990 F-150 has just started idling at 2500 RPM, all the time. I tried a new air idle solenoid, and that didn't work, same problem. Does anyone have any idea where I could look next? It is a 5.0 4X4.

 

I had a 1990 Mustang GT 5.0 that would do that. Here in california they would reformulate the fuel for the summer and my car didn't like that. High idle sometimes. I would solve it by sticking in some fuel cleaner when my fuel tank was about 1/3 full and it would help the problem.
Hope that helps.

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2000 f-150 red, XLT, 4x4, 5.4L, 3.55, sliding rear, 60/40, towing package (1.42" rad. included), ORP keyless entry.
Airaid FIPK, SI/DO Flowmaster 40's.

 

went searching here today (also getting used to the 'new look') on 'high idle'. my warranty just ended as i was on vacation (325 mile trip) after my ride i found my motor to be idling at approx 1500 -1750 rpms. this never happened before.

drove today, and the same exact thing happened.

i know i had the idle drop problem after installing the k&n fipk.
think this was due to too much oil on the filter. i would clean the maf sensor and it was good, wondering if this high idle could be related. i ran the truck for 4 1/2 hours straight at 75-80 mph, dont know if that matters or not, but after doing so i have the problem.

it is not constant, weather was too bad today to clean maf again, hopefully i can do this tomorrow

has anybody else had this??? would love to hear ffrom anyone who has. curious as to what i can do to fix it. any help would be greatly appreciated.

 

I had a GM one time that had the high idle. It was due to a vacuum hose pulled off. Don't know if this would apply here. Might be worth taking a look.

 

I WAS HAVING A PROBLEM WITH THIS SORT OF THING ON MY '99
DEALERSHIP (FINALLY) NARROWED IT DOWN TO A THROTTLE POSITION SENSOR. I GUESS THEY JUST GO BAD SOMETIMES...

HAPPENED AGAIN (1 YEAR+ LATER) SO INSTEAD OV MAKING APPT., WAITING, RIDES TO WORK...ETC. WENT TO LOCAL PARTS STORE, $20 AND 10MIN LATER, GOOD AS NEW.

JUST MY 2CENTS...

 

this is the truth, and before i start, thanks.

checked the hoses, took off the k&n, cleaned the intake.
had my wife start the truck to make sure all was okay.

she does, then goes in the house
i go in the garage to clean up

i hear what sounds like a huge tree falling down so i turn around quick. i look and see my truck across the street in my neighbors yard.

my driveway is sloped down.

my wife did not leave the truck in gear
she did not use the parking brake

i now cant open my tailgate, and the bumper looks to be flush mounted. tagged a nice sized maple tree (luckily no people)

going to the body shop tomorrow, wish me luck boys
(for the two seconds she ran the truck i didnt have the high idle though)

 

mine was doing the same thing, I decided to get rid of the K&N and use some intake cleaner. It seems to have returned to normal.

Though I don't know if mine was the same problem. it would idle at about 1200-1500 rpms at stop lites with the clutch in. After a little while is would idle down. (about 20-30 sec)

Hope this helps.

 

I have a '92 F-150 4x4 with a 351, I had the same problem. I also changed the air/idle solenoid and that didn't fix it. I found that the problem was the throttle position senser ( $80 from a Ford dealer) it doesn't always show up with engine scan. To change it, drain your radiator down a little and take off air intake hoses, then take off the throttle body, 4 bolts. Take off cooling lines, unplug sensers, and remove throttle cable. The tps senser is on the bottom its held on with 2 screws. While you have it all apart clean inside of throttle body and butterflies. It's pretty easy good luck.

 

thanks for the info.

it did this again to me yesterday.

will try may hand at fixing it this weekend.


thanks again.

 

I had a Bronco which had the same problem. I changed everything on the throttle body with no luck. I finally changed the upper intake manifold gasket and it worked. Part of the gasket was was gone causing to much air entering the mixture. Good luck.

 

got my truck back yesterday from the dealership.

they fixed the high idle problem. i was afraid to replace parts when i wasnt sure exactly where the culprit was.

they put in a new air bypass valve throttle assembly. part-no. f65z*97f715 (not sure of the suffix as it didnt print on the ticket)

charged me 61.90 for the part. it started with 35,890 miles on it while i was in canada on vacation. being that i brought it in with 37,000 miles (when i got back from vacation) they would not do it under warranty.

it has been perfect since they have done this.

thanks to everyone who posted with info.