I had the plugs replaced and mechanic also found two bad coils. I had replaced injectors previously. To cut a long story short, getting misfire on #1 cylinder. Swapped coil with #2 cylinder to see if problem moved and received a p302. Unfortunately this did not work and still receiving misfire on #1. It is driving my crazy, since coil, injector and plug have all been be replaced. Hope someone has experienced a similar problem and has a possible solution.

Thanks Don

 

I am hoping someone has the solution to this problem, as I have the same exact issue. Mine is misfiring on #5, and around 50mph uphill my engine starts misfiring bad and the power boggs completely down. Even on regular driving I can feel the engine not having much power.

 

You might need to replace ECU CPU cause it stores memory on engine management and causing problems to stay! I hope this helps but I am not sure I recently got 2007 Ford F150 XLT supercab 4x4 5.4L like 4 days ago and I am 12 year old mechanic myself I hope I am right

 

Or faulty wiring or too much moisture in the plug boot make sure its dry and add de-electric grease hope that helps do that first tho!

 

You need fuel, spark and compression. You'e th coil, is the spark plug good? (Just because its new, doenst mean its good) Is the injector firing? (Just because its new, doenst mean its good) Have you dont a compression check? Maybe you have low compression or a cracked valve. A leakdown test is the next place I would start after checking to see if the injector is firing.

How do you know it is still missing on #1? Did you clean the code and it returned, or are you doing a power balance test with a scanner?

 

After a couple of frustrating days, the problem was tied to a bad plug. Even though it was new, the parts house had given me a bad plug. After replacing plug, engine runs like new. It was orginally stalling at 45mph and had to give it a little gas to get past the point. I thought the tranny was having a problem. It turned out to be a bad coil. If you are having these problems and haven't replaced plugs or coils, that is where I would start and don't forget even new parts can be bad.

Don

 

Don, I found out that when replacing plugs. You have to replace rubber boot too cause the old plug made a imprint on boot and new one is little different and makes new imprint inside boot so if still using old boot with new plug cab cause moisture and air getting in and causing misfire! So most of people don't realize not replacing boot can give alot of error and guesswork and money wasted by replacing coils, injectors, etc

Daniel

 

I have a 2001 Ford F150 that is misfiring on cylinder 1. I change the coil pack and it still is misfiring, but I have found out the new coil pack is arcing. My question is what is causing it and how to fix it? Did I buy a bad coil, I got it from auto zone.

 

where is it arcing to, and did you buy an OEM or an OEM replacement.

 

It's arcing by the spark plug well, and I bought a OEM replacement.