I have an 1996 F250 automatic with the 460, 4WD CC shortbed. It has 111k miles on it. I have owned it for a year and half and have put about 4k miles on it (use it primarily for towing 6000lb trailer).

I have been concerned about the lack of power the truck has when towing my fairly light Outback travel trailer. Everyone said give it a tuneup and see if that helps.

So this weekend I did that. Replaced belts, distributor, rotor, plugs, wires, air filter, oil change, upper radiator hose that had small hole and a little seafoam. Truck seems to be running great. Only problem is the check engine light now comes on. It comes on after a few minutes of the truck running. The light has never come one before.

This is odd to me as the truck seams to be running great yet the light now comes on. It isn't automatically on when I start the truck, just after a few minutes of running.

Any ideas what this could be? If I remove the battery cable for 10 minutes will it still come on? I assume so because the light is not permanently on.

Any advice is greatly appreciated. Thank you!!

 

Pull the codes, that will get you going in the right direction. Just a hunch without the codes, but i would guess it is a vacuum issue. The Vac lines become brittle and crack easily with age and heat. When performing the tune-up you have probably broken a vac line.

 

I drove the truck again after it sat for a week. Still runs great. Noticed that the check engine light doesn't come on until you hit about 40 mph. Not sure if this helps diagnose.

 

Pull the codes.