That's what you pay mechanics to diagnose. You must also check for fuel injector pulses and fuel pressure. That will tell you if you have a spark problem or a problem with something common to both systems.
You also have to consider a defective pick-up coil or ignition module. Those are both inside the distributor. Even the rotor can become shorted, but that is not very common with this distributor.
Dec 9, 2016 at 9:05 PM