Slight misfire or engine bucking

ford
engines
misfire
f150

#1

The 4.2 engine in a 97 Ford PU, stick shift seems to misfire slightly and “buck” when climbing slight grades before shifting should be necessary or when accelerating to pass while driving on the freeway. Where do I start with out changing every sensor or other gadget piece by piece?


#2

How does it act when accelerating at full throttle?? Will it do that cleanly?


#3

There is no “bucking” after the thottle is held down for a time nor does it idle rough. The plugs and wires were replaced in the last year.


#4

Fuel pressure is not something you change; but, one could MEASURE it. You know. Low fuel pressure means low acceleration, right? That would be after the fuel filter was changed, just to do it right.
Air filter? TESTING sensors before summarily changing them?


#5

Any check engine light? If so, having those codes read might point you toward what things to test - though as hellokit said fuel pressure/filter would be the first thing to look at either way.


#6

I have not encountered a check light, however my mechanic did when he was inspecting the truck. The computer recorded a misfire in cylinder # 2. The spark was tested and deemed acceptable, the light was turned off and it has not re-occured to date, that was about 1000 miles ago. I will need to look into measuring the fuel pressure, the air filter was recently changed.

Thanks


#7

Just for funsies, change #2 spark plug, and switch #2 spark plug wire with another. If it still misfires, you could swap #2 fuel injector with another (if you don’t have to take the plenum off, to do so). If the misfire moves, that fuel injector is your problem.
Was the fuel filter changed? It’s suspect.