Tach out, engine sluggish, what happened?

Three times in the last week I've gone for a drive, stopped somewhere, then restarted a still warm engine some 30 minutes later. On restart, the engine seemed sluggish, I checked the tach and it was out not showing anything. Each time after driving a short distance (i.e. a block) the tach came back on as the engine kind of suddenly spit and rev'ed about 1000 rpm, then seemed to run fine. Any idea what's going on here? My concern is I wasn't running one bank of the motor, but would this knock out the tach as well? (Speedometer was OK). Thanks for any advice.

 

crank sensor?

 

The tach signal on your MondialQV comes from just one of the Digiplex units. If you swap Digiplex units and:

1. You still have the same problem (low power and tach dead), most likely something upstream like the crank sensor for that bank as Dave mentioned, or

2. If you still lose power, but the tach now works OK, not a good sign for one of the Digiplex units.

Of course, have you already check/done the improved grounding for the Digiplex units?

 

Sluggish as in a 4 cylinder mondial when the tach doesnt work. My boxer didnt have too much steam when the fuse pump block melted for one of the pumps either, leaving me with 6 cylinders.

 

You'll find it is probably an intermittent fuse problem. Also, when the tachometer goes out, you're not necessarily running on 4 cylinders, but are running a defaulted minimal advance curve, which makes the car very sluggish.

 

Winner.