Weird misfire, mainly under load.

[manlavi95]

This has been happening for some time now, when I cruise and it puts it into the highest gear, there is a very obvious miss, because the vehicle starts surging. When I floor it, it misfires and also backfires. I replaced one of the coils, still happened, replaced the other coil with the coil I pulled off, still did it, cleaned the grounds under the coils with sandpaper and the bottom of the coils themselves (Aside from the new one), and it's STILL doing it. Can't tell if it's an ignition problem or a fuel delivery problem.

Oh yeah, it's a small block Windsor 302/5.0

 

[partsman48210]

Try checking the condition of your plug wires. I've had cases where the wires look fine but one slight crack allowed the arc to jump to the cylinder head. It was noticeable in the dark with the engine revving

 

[Turdle]

Try checking the condition of your plug wires. I've had cases where the wires look fine but one slight crack allowed the arc to jump to the cylinder head. It was noticeable in the dark with the engine revving

^^ try spraying water along the wires and on top of the coil packs at night, then fire up the explorer and watch for the fireworks

A cold engine will help the water stay around longer.

Also, even if the plugs are relatively new there could bad a bad one. I would think the check engine light would be on?

 

[manlavi95]

^^ try spraying water along the wires and on top of the coil packs at night, then fire up the explorer and watch for the fireworks

A cold engine will help the water stay around longer.

Also, even if the plugs are relatively new there could bad a bad one. I would think the check engine light would be on?

Nothing seems to have popped a CEL yet, which has surprised me. But I'm definitely going to try the water idea.

 

[manlavi95]

No fireworks that I could see.

 

[manlavi95]

correction, fireworks everywhere. The previous owner must have done plug wires and they finally wore down, they're chafing on everything metal.

 

[Turdle]

There ya have it

I bet with new wires and proper routing away from the manifolds, you'll be running like a champ, and the fuel economy will shoot up.

 

[manlavi95]

There ya have it

I bet with new wires and proper routing away from the manifolds, you'll be running like a champ, and the fuel economy will shoot up.

I'm sure, they're rubbing against brake lines, one was laying on the steering shaft and had polished a line on the shaft, on was crimped against the coil bracket, just ridiculous.

 

[swshawaii]

Split wire loom

1/4"
http://www.napaonline.com/Catalog/C...oom-Black-Split-Poly/_/R-NW_737299_0293961126

3/8"
http://www.napaonline.com/Catalog/C...oom-Black-Split-Poly/_/R-NW_737300_0293961127

 

[Dono]

Its interesting you would post that you had no CEL's. I had at least 2 really bad plug wires, missing, backfiring, the whole ball of wax. No CEL's either. My 4.0 ohv pop's a misfire CEL if you look at it the wrong way. The 5.0's don't seem to be very sensitive to misfires.

 

[Turdle]

Its interesting you would post that you had no CEL's. I had at least 2 really bad plug wires, missing, backfiring, the whole ball of wax. No CEL's either. My 4.0 ohv pop's a misfire CEL if you look at it the wrong way. The 5.0's don't seem to be very sensitive to misfires.

Only if it is fuel injector related it seems.

 

[manlavi95]

Its interesting you would post that you had no CEL's. I had at least 2 really bad plug wires, missing, backfiring, the whole ball of wax. No CEL's either. My 4.0 ohv pop's a misfire CEL if you look at it the wrong way. The 5.0's don't seem to be very sensitive to misfires.

Yeah, if I gunned it and it downshifted, it would misfire, pop flames, and have no power, and it STILL didn't throw a code.