2002 GTI 4TEC engine miss

[Riverrats2]

I have an intermittent engine miss at all RPMs. I have replaced spark plugs twice, no change. I have installed 3 new spark plug coils, no change. I have replaced 3 new fuel injectors, no change. I have found the #3 cylinder is the likely culprit by removing and installing electrical connector to the coil. RPMs will pick up and then decrease at idle as well as no change in RPM. I have noticed a weak spark when running and installing an additional spark plug to the coil and looking at the spark at the electrode gap. Not sure where to go from here. Looking for advice on what I can do next. This PWC is immaculate with 29 hours on it. New to me, and this unit has been in storage for 11 years. I removed all fuel form tank and removed and cleaned fuel pump, lines and replaced filter. Very little fuel was in tank to begin with and started immediately after cleaning. I believe this problem was not new to me since I found 3 new ignition coils with the PWC creating a suspicion when I took possession.

 

[mkov608]

Have you checked the resistance of the wiring between the ignition coil connector and the ECU? It's possible you have a faulty driver in the ECU. You need a secondary ignition wave form analysis to determine what type of misfire you have.

 

[Riverrats2]

Thank you for your response. I will verify the resistance values of the wires between the connectors. I will need to take the unit to a dealer for the secondary wave form testing if required. I thought about exchanging the ECU, however that does not appear to be an option.

 

[mkov608]

Most dealer shops don't have a lab scope or know how to use it.