spark plug wires
If you can actually SEE arcing behind the water pump (i.e. - in the location where the Opti is mounted on the engine), then you need to at least replace the Opti's cap and rotor, maybe the entire unit; but you will not know until you take it apart and inspect the unit for damage / water / issues.
Be sure to inspect / check / test the 4-pin Opti extension harness for issues too (Just unplug it and then look at the end and inside the Opti for evidence of problems).
Have fun!







