2.3L ('83-'97) cold start issues 2.3

[trent94]

So, my son's 1st vehicle is a 1994 ranger XLT 2wd. It's getting better, but subzero temps exposed an issue.. I've figured out that my coils are good, but cylinder 1 spark plug isn't firing ever, and cylinder 4 is random.. all on the exhaust side (rear coil) all others firing correctly. ICM? I do have 12v at both coils. Thanks for any help.

 

[tomw]

Those two plugs are designed to flash at the same time. Spark current goes to the center of one plug, jumps across to the ground electrode, jumps from the other plug ground to the center electrode and back to the coil... more or less. Ditto for #2 & #3 cylinders. I do not claim to understand how the 'ground' knows to jump across a plug at the other end of the engine, but they do...
I would check the plug wires resistance. Checking at each end, ohms should be less than infinite, vague memory of about 1k ohms per foot of plug wire. If the conductor is broken internally, the spark would have to jump a gap inside the insulation, in addition to both spark plug gaps. That can lead to interesting plug firings or lack thereof.
Check the ohms. If the plugs are old, or have evidence of 'tracking' on the ceramic, I would replace plugs and the wires involved.
tom

 

[RonD]

+1 ^^^

Ford uses a Waste Spark system
In your 1994 2.3l you also have dual spark plugs in each cylinder
And you have a separate Spark module, and ICM(ignition control module), its in the front of lower intake

Waste spark means 2 spark plugs share 1 coil in a coil pack, as said above
In the 2.3l, cylinders 1/4 and 2/3 are the pairs that share a coil

Dual spark plugs adds more power so BOTH spark plugs in the same cylinder spark at the same time or there would be no benefit
So if a 2.3l has a misfire then BOTH spark plugs in that cylinder would have to not spark, not just one

Dual spark plugs means dual coil packs
The engine can run on just one coil pack, 4 spark plugs, just fine, the 2.3l engine did this from 1974 to 1988 before dual spark plugs were added, there would just be less power but no misfires

The ICM was a common issue on these when they got older and the wires for the ICM
The ICM runs the coil packs, sparks them, not the engine computer, it runs just the fuel system, the injectors

 

[trent94]

ICM was the cure! -3 this morning in eastern iowa and it started! It's ready for my son to drive to school this coming week. Thanks for the help!

 

[RonD]

Good work

Thanks for the update and THE FIX