Hey all, I've got a 1997 f150 with a 4.6 and 109,000 miles and have had some issues with it in the past. What I have been dealing with for a while is a detonation issue that I cannot seem to resolve but I have not had too much trouble through the cold months. The issue I am having now is if i'm going up a large hill and I go full throttle, or put it in second and full throttle up the hill you can hear it running rough. I can't feel a missfire, no engine lights, but the exhaust sounds terrible, like it is not firing right and seems sluggish. I thought at first maybe it was just a normal sound, but the other day it got to about 3k rpm and all of a sudden it seemed as if a switch was flipped and it took off and rev'd right out with a ton more power.

On occasion sitting at a redlight you can feel the truck miss a few times, but nothing serious during normal driving.

Over the past few months I've replaced a lot. Plugs/wires, fuel and air filter, pcv valve, upper O2's and other maintenance. What i'm wondering is if the coil packs are going bad, they are original as far as I know.

Posted twice by accident. Sorry.

Any idea's are appreciated. Thanks!

 

Have you run the codes? Most misfires are P030x codes. You don't have COPS in that truck, so you have wires and 2 coils (4slots each). If you read the codes and post them back here, we can try and narrow down your problem. As it is, all we could do it tell you to throw parts at it, and that can be expensive.

 

Thanks for the feedback. No codes that I am aware of. I can try to get to a scanner that will show me history codes and see if anything came up recently. But from what I've seen these older Ford computers are pretty slow and don't pick up a lot of the small stuff.