I have a 2005 Ranger that only runs on cylinders 1 & 4. This problem came from the truck sitting for a few years but it worked before it was parked. I have done everything I can think of to try and diagnose the problem. It threw a P0351 code which is Ignition Coil A Primary/Secondary Circuit Malfunction.
Here is what I have done so far:
- Compression test (all cylinders are very strong)
- Injector test (all injectors fire and supply fuel to the cylinders)
- Spark test (only getting spark on 1&4 with multiple brand new ignition coils)
- Replaced PCM (same issue present)
- Checked harness/ connectors for breaks and loose connections

I have also replaced the plugs and plug wires with brand new parts and that did not solve the problem.

After all of that I am at a loss on what it could be any input is greatly appreciated. Are there any other tests the I can do to find the issue?

 

You don't mention the coil pack/block. I've had to replace the one on my '03 2.3 liter Mazda B2300 at least twice. Symptoms of a failure on mine are very rough-running engine, very low power. Easy fix, the coil is mounted with four star-drive screws on the passenger-side rear of the engine, looks a bit like a distributor. Be careful with the screws—don't drop them.




https://www.walmart.com/ip/Ignition-...erId=101002405