It could also be a faulty wire or connection. I had a lose connection for the wire inside the distributor that goes to the tach. I cleaned the terminals off and connected it securely and the problem went away.
The ignitor has two jobs. First, it acts as an interface between the ECU and the ignition coil, switching power to the coil off and on (triggering a high voltage pulse to a sparkplug) when signaled by the ECU. Second, it splits off the ignition signal to drive the tach.bittles110 said:BTW, what does the igniter do?