>I missed that.  Question is, was the engine really varying that much or was it something else?  The EM2 >gets tach info by watching the primary injector switching.  If the injector drive was erratic that would >make the tach go wacky.  John said controller A & B worked the same so I ruled out controller problems.  >An intermittent connection to the injector would fit the symptoms though.

 

If anything in the ignition loop is intermittent (e.g. coil or spark plug) the engine will stumble causing a loss of RPM. Won’t the controller see wider spaced signals from the crank angle sensor and slow the injectors to match? I think the thigh bone is connected to the leg bone…I mean things are interdependent. If the RPM is based on injector pulses and injector pulses are dependent on crank angle sensor, then couldn’t it be anything that slows the engine down from partially clogged injectors to bad coil(s)?