Theres no reference to intermitent problems in the fsm, either the tach works or it does'nt.
Too bad you dont have an error code to go off of :?

im curious, because i assume that the fault is when i feel the hessitation. This is showing as a malfunction in the engine speed circuit causing the tach to default to 0rpm.

Yeah, getting back to this subject, that is what I've thought. Basically an ignition related problem manifesting itself through the tach., but not setting a DTC. That'* where it gets difficult to diagnose. Does the symptom still exist, or occur?

mark; is it safe to assume that when the PCM sees the fault it sets the tach to default 0rpm, and wont read until the next start cycle???

i assume it does, i havet had it happen since friday, but i dont drive it on weekends anyway... i hopefully will be borrowing a scan tool for a couple days so maybe i can see something when the event occurs again


on a side note, Boosty is sending me another ICM that im going to swap in and see if the problem still persists with another ICM

Yes, I did read in the FSM about the tach default to zero with PCM, or Crank Sensor fault, however I can't find conclusive information that it resets on the next start cycle. I'll do some more looking around during the interim.