My truck starting missing recently. I had it checked but they found no codes. The check engine light has not came on.

The skipping is primarily when the engine load is increasing. For example, running highway speeds on the interstate and climbing a slight incline. As the truck starts slowing down it will start missing. The mising also seems to get worse after the engine has warmed up.

Not having any codes is what has me confused.

Any suggestions?
thanks

 

I'm having a very similar problem with my 1986.

Been through plugs, wires, cap, rotor, EGR valve (EGR code), several throttle position sensors, one of which was bad out of the box. Upshifts too soon. Other sensors check out. Seems better on humid days (!?).

Infuriating, but I love the darned truck (it was my Dad's).

If I find a solution, I'll definitely post it - you and I are not the only ones that have had this problem.

 

An interesting comment from Yahee, "seems better on humid days" What does that mean? Air is less dense due to the moisture but has more mass because of the moisture. Are we all thinking of fuel/air ratio? What sensors control mixture, especially 20 years ago.

 

I have have had the same problem for about 5,000 miles. Runs fine for about 10-15 minutes---then there is this miss. sometimes at idle and when pulling a gentle hill on highway, also from stop light occasionally. Changed spark plugs, rear end fluid, transmission fluid----no help!!! Driving me crazy (which didn't take much). Anyway I finally checked vacuum hoses for frayed, cracks etc. Checked good. While inspecting in the area noticed a wire that goes to the two sensors on throttle body were routed resting on the top of radiator hose flange. Found the wire insulation melted on bottom where it contacted the flange. Removed the resting wire and tie wrapped to something else. PROBLEM SOLVED. I will change wires and sensor at later date. Hope this helps someone, Cuz this site has help me a lot.

 

My Truck----2003 F150 supercrew 2wd 4.6l

 

Seems like a common problem. I had it myself with the same symptoms and after changing the plugs and wires it went away. For some guys it does not seem to work, but the general consensus is that it is a spark issue. I searched a lot of threads to figure it out and I would suggest checking for a bad coil because this is the other solution that seemed to work.

 

ed2002f150 hit it on the head: '...running highway speeds on the interstate and climbing a slight incline...' Fits the symptom to a tee!

I forgot to mention replacing the coil, too. Thanks Mr B.

I'll try roadkingman's fix. Seems obvious, but haven't looked as closely as I probably should have. Thanks!

I had a mechanic suggest a clogged catalytic converter, but it just FEELs like an electronic problem; Abrupt miss, not like a fuel or air problem, but I could be wrong.

 

I am having the same problem. Changed plugs but did no good. When it's cold it runs fine. As soon as it runs 10-15 minutes it starts missing. I have COP, so I guess I have to start checking them one at a time. I can not, for the life of me, figure out why there are no codes as bad as this is missing. Any suggestions would be appreciated. ED

 

All should consider replacing your COPs. Sounds like the common low grade misfire that the misfire monitor doesn't pick up well so you don't get a CEL.

 

I am trying to determine which COP is bad, or do you think I should change them all to be on the safe side? Also, where can I get the best price on them? Any suggestions? I see several places online to buy them that seem very reasonable, but I am suspicious if they are too cheap. Thanks. ED