Kevinnjaime

I have a 07 f150 with the 4.2L V6 with a 5 speed. At low RPM and under load the truck has a miss fire but no check engine light? I have changed the coil pack, wires, plugs, fuel filter, cleaned the air filter and the MAF sensor and the throttle plate. Please help I'm at a loss now?

skicyp

So odd, I have a very similar issue, but on the 5.4L. When doing 40mph, and Tranny is in OD at 1000-1100 RPM, if I hit a hill or start losing momentum and I barely give it some gas to keep up the speed, POW, I get what feels like a Transmission problem, a jerk shift. I towed a boat awhile back and the issue was pronounced. I hit the gas to get on the freeway and it went through the worst bout of this I have had. Without load, just commuting, I get the normal OD downshift jerk.

After reading more then my fair share of posts, the most common thing people say they are doing is the spark plug replacement. I can't get a good feel if people are doing the COP replacement or not. Some say they do, others appear to say they replace one or the other, but this appears to be on ones where they are getting a Code. I have run two of the ACTROL/ACTRUL?? code readers and everything is fine. Then my buddy ran his "Chinese knockoff" with a app and sure enough he got some weird code (Torque BHP - says "MID: $30 $0) and he says it could be the Oxygen sensor. Three more codes come up as "Not able to Read due to dependent test". Well, my engine just happens to have a total of 4 sensors. So..... I kinda want to change those out before I start to worry about a cat problem. I'm thinking just replacing the DY-835 (front sensors) first.

I've seen a couple of posts that suggest a replace of the Oxygen sensor along with plugs at the same time is a good thing. Who knows?

Open to any and all suggestions....

Thanks, and good luck.

Big_Ed

Change your coil packs before your oxygen sensors. Get either msd or accel. Same power input, but higher voltage output. When changing each one, take a minute to check the bores for the plug boots going into each cylinder. if there is a bunch of gunk or trash, remove it. ALso, did you replace the BOOTS for the COP's? if they are worn or waterlogged or mushy at all, they will allow the spark to jump to the head THRU the boot.

skicyp

Thanks Big Ed... I ended up starting by just doing a plug replacement (thanks lisle tool!) and sure enough that fixed the issue. I didn't spend 1000 at the dealership (what a ripoff) and thanks to All the posters on this site and the YouTube videos was able to do it on a weekend. I didn't replace the COP's or sensors, but they were on my list in case the plugs didn't correct.