1994 mazda b4000

[twayne410]

can someone please help me, this truck is fireing weak on the 2 middle outputs of the coil,have replaced the coil with new one and still doing same thing.anyone have a idea whats going on

 

[IslandFord]

Firing Pairs

The middle two spark plugs fire at the same time for some reason. That's important to you because you need to check both spark plug wires and spark plugs. Theoretically, a short in either secondary system will cause a "weak spark" as you described. A larger than normal gap on either plug would probably cause a stronger spark on the wide gapped plug and a potentially weaker spark on the other side. If the wire has a gap in it, then the spark will be split between the wire gap and the spark plug gap which would leave what appears to be a weak spark at the spark plug. The gap may also be within the boot.

To find the culprit you could switch plugs with another cylinder and see if the problem switches with it. Then you would switch a wire onto the same cylinder. If you would rather not take the time to do this, go buy some wires and plugs and change them all. If you are on a budget you can try the switch and find the exact part, then buy a used wire to replace it. Good luck.