knocking under WOT????

[Abraxsis]

Just this week on the interstate this knocking developed under WOT. Its coming from right behind the driver's side floorboard. Not from UNDER it but from the engine in front of it. Any ideas? I was thinking maybe a plug is fouled, or maybe a plug wire is almost gone.
Any help will be greatly appreciate.

BTW if you havent cleaned your MAF sensor I HIGHLY recommend you do it. My gas mileage has nearly doubled on the interstate.

 

[Abraxsis]

Oh I forgot, its only under load. Like when I going up a long, or steep, hill. If the road is flat I have no problems at all.

 

[Blaine122300]

Does it only happen at WOT?
If it does, it may be something simple. Try fuel injector cleaner/octane boost. If that doesn't help, try resetting your computer if you haven't. You said that you recently cleaned your MAF, that may have something to do w/ it.

Just some Ideas.

Andy

 

[DarkFox1]

had the same thing happen.. only mine was flat out skipping.. turned out to be a dead plug wire.

I took mine to the dealership and made the truck do it, they immediatley knew what it was (good that they know SOMETHING about cars huh)

if you dont trust them.. enough to have them do it.. I'd just start by checking the plugs, if they all look good.. you may want to test the wires.. I'm not sure how do to a wire test. and since it only happens under strain you may not find anything unusual sitting still.. hope that helps, I'm not the best at troubleshooting truck problems... else I wouldn't complain about my own all the time.

I'm not touching the maf costs way too much to replace to risk screwing it up with a cleaner

 

[Alec]

If you've already cleaned the MAS, then I suggest plugs and wires, fouling fuel injectors, or a fuel filter that's starting to get clogged.

I do not recommend running more octane as a fix, this can make the problem worse in the longrun. Might want to try running some good fuel system cleaner or having a professional fuel injector service.

 

[Abraxsis]

Well seeing I have two new O2 sensors and new Platium plugs in the glove compartment (where Im sure theyre doing a lot of good ) Ill go have them put in today. Thank guys, everyone still post though if they think it could be something else.

 

[MrShorty]

I would check for vacuum leaks and check/tighten your lower intake manifold bolts. That's what fixed this problem on my '92, and it seems to be a common reoccuring problem on the 4.0 OHV engine.