Cylinder four misfiring

Hi,

You indicated you got some spark to the wire harness. It arcs to ground. Where exactly is this happening?

Also, if compression is good and you are getting spark to the number 4-cylinder spark plug, the next thing would be related to the fuel injector.

I attached a portion of the wiring schematic below and circled the number 4 injector. Note that all injectors have a yellow wire. That wire will have 12v with the key on. Check and confirm the cylinder 4 injector is getting power.

If it is, we need to determine if the yellow wire with a purple tracer is providing a ground path. The best way to do this is with a Noid light. This type of light simply plugs into the connector and will strobe on and off if the circuit is working. If that isn't an option, you can use a test light to see if the circuit is being completed. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

If that tests good, you have spark to the plugs, and the compression is good, in this case, suspect the injector has failed or is plugged.

Let me know what you find or if you have other questions.

Take care,

Joe

See pic below.