My 1986 F-150 with the 302 ci. engine and auto trans has a engine miss when accelerating. The miss is most noticed when accelerating slowly, or climbing a steep grade. I don't notice the miss when stepping up into passing gear, or driving on flat roads.

I have replace plugs and wires. Throttle position sensor, and the coil. I also notice the miss( not all the time ) when the engine is at idle. There is no miss when I lock the brakes and step up the engines rpm. Any hepl would be appreciated. Thanks

 

Do you have any computer codes? Also try and move sparkplug wire #7 away from sparkplug wire #8. They both go to the drivers side rear, and would naturally run side by side in the holders, but since they are next to each other in the firing order, they can crossfire easily.

 

I had this same prob with mine recently. I fixed it with the help of all at this forum.

1. Check that your plug gaps are correct, I accidently closed up the gaps on a few of the harder to get at plugs when re-installing. haynes suggest 0.044inch /1.1mm

2. As franklin2 has already stated they do have a tendency to crossfire. I fixed this one with corrogated tubing over the plug wires.

Good Luck


Nordo

 

I have had this truck in the shop many times for the missfire problem. Non of the mechanics could located the problem. I posted on this forum and recieved the " Correct " diagnosis within a short period of time from Franklin2 and Nordo. I am impressed. The engine runs like new. Thanks sooo much for taking the time to reply. This site is what the internet is all about. Networking to make live a little easier.