Fordlovernow

My 03 f150 has a hesitation during low rpms while accelerating. But if i use a high octane it stops. I dont have anything specail just a CAI and a flowmaster 50 single in dual out exhaust. CEL isnt on and i changed the plugs two weeks ago and didnt change anything. Any thoughts?

fuchs1bl

Dumb question, Did you hook back up the plug wires properly and in proper firing order?

kookookachew

Do you put on the modifications yourself? If so, did you reset the computer after doing them? Usually the computer needs to be reset by unhooking the battery so it can calibrate for the changes.

If the computer has been reset, have you tried some good quality fuel injector cleaner?

kookookachew

I'm also tempted to say a bad coil on plug or C.O.P, but you say it goes away with high octane.

jdf150

Also might not hurt to clean the MAF sensor. Also some codes may be in the computer although the engine light is not on.

Dirtbuster1

It would be hard to hook the wires back up wrong with coil packs! They are to short to hook up to another cylinder.

JJ1983

Very true, my Edge Programmer picked up the codes for my truck when a COP went out, although the light didn't come on. You know, I have never checked the MAF on my truck. Sounds like a job after work today

JJ1983

Could you have a lean condition? I had a truck that would pop thru the intake every now and then (a 1986 F150 302 FI) and it ended up being dirty injectors, I changed everything else before trying that. I did one of those chemical cleanings to them when I worked at a shop a few years ago, worked wonders.

Dirtbuster1

Have you changed your or checked your air filter lately?

Fordlovernow

I cleaned the MAF and it still did it. My no. 4 coil was bad so i changed that. I have been running lucas injector cleaner about every other fill up and that seems to help until i go back to 87. No i havent reset my computer yet but i will try that to see if that will work.