The truck in my sig is starting to miss or hesitate. When I'm sitting at a light and it does it the tach will drop momentarily. When at speed the truck bumps and jerks as if the spark has cut out and then back on again. It is so bad going up hill that I sometimes feel I won't make it up so it gets worse under load.
I pulled the codes today and got KOEO 111, 10, 111 so my KOEO tests passed without any issues. KOER only gave me 311 - Thermactor air system/fault during engine run self-test.
Can the Thermactor system cause the symptoms I've described? If not, where can I look?
My truck is acting the same way it did when one of my spark plug wires blew a hole in the boot and the spark was jumping to the block. I don't think it's the case now as I've recently replaced my wires with Ford Racing 9mm wires.

Any help would be appreciated.

 

Anybody have any ideas? I'm going to pull the plug wires today and check them but does any one have any ideas what else may be causing my truck to miss/hesitate?

 

Did you replace the cap and rotor when you replaced the wires?

 

Same question for the plugs...

 

Here's a possibility and the "fix" I did on my truck.

I had installed a fiberglass shell on my truck that had a brake light and an interior dome light.

To get the shell dome light to operate, I used a "tap in a fuse" in fuse slot #8 under the dash.

As it turned out.....the "tap in a fuse" I installed opened the #8 fuse slot just enough that the fuse made a random intermittent connection and my truck would randomly miss, shut down the tach and speedometer, jump and lurch and throw the truck into "limp mode" 'till I finally found it.

Do you have any accessories tapped into the under dash fuse block ???
Worth checking.

Also, make sure that the connectors on the wires (+ and -) @ the coil are in tip top shape and your not getting spark jump from the + side of the coil to a ground.

Just a couple of places for you to check.


Bob

 

Thank you for the replies. Yes I replaced the cap, rotor, wires and plugs at the same time.
I pulled the plug wires today and noticed the two plug wires going to #4 and 5 cylinders were cooked. The rubber/silicone boots felt like plasticine and I saw where spark had been jumping through a hole in the boot from the spark plug connector to the engine. When I replace the wires it will be the fourth set in two years. It's always the #4 and 5 plug wire that gets fried.
I think I probably have an exhaust leak that's blowing right on the boots and they can't take the extreme heat. I'm not positive as there is no carbon buildup on the boots but it's the only thing I can think of at the moment. Right now I'm not sure what I can do about it short of pulling the engine and fixing/replacing the exhaust.

 

I was having the same problem your are having. I replaced my MAP sensor ran cherry again. something you might want to check