My 1998 ford 150 (130,000 miles) misfires only in overdrive on a slight incline , way before the transmission down shifts. I got around 30,000 miles on the new plugs, about 8000 mile on the wires. I also checked the coil pack. The manual states resistance on the secondary should be 12.8-13.1 kilohms, if resistance is not within specification, replace coil pack. My 2 coils read 14.4, so I replaced them. This did'nt help either. There is no engine warning light on. I had my transmission rebuilt last week and they ran a scanner on it and it didn't show anything wrong with my engine. They told me the ford garage has a high tech scanner and it might show something.

I also changed air filter, fuel filter. Has anyone here had the same problems?

 

I think I have the same problem as you. I have an issue when I press the accelerator when the truck is in overdrive, it feels like it starts to jerk a little. The truck has 93k so I changed the spark plugs which were pretty bad. Truck runs better but still jerks a little but not as bad, so I changed the tranny fluid but didn't correct the issue. Not quite sure what it is.

 

hey heatwave what brand of wires did you put on it? The 4.6's were NOTORIOUS for wires. The aftermarket wires I've seen only make it worse. The best way to tell is to look for carbon tracking down the insulator of the plug. If they're ok, I dunno what to tell you except have a ford dealer put the WDS on it.

 

Thanks fordtech92, Yeah I put aftermarket wires on my truck, O'Reilly's best. Today I went to the Ford Dealer and bot a set of Motorcraft wires. They also told me about the wire problem on the 4.6 ...Now she purrs like a kitten up hill in O.D., No misfire. Thanks again.

 

not a problem