Here's the story:

1) Last winter my truck shut down on the way to work. Ran the predator for codes and it said crank position sensor (I forget the number). Got it to the dealer and they scanned it and it was missing...disco'd the edge and it fired up...ok, so the edge went in the garage and hasn't been installed since. But I have noticed the tach is "jittery", bouncing a few hundred RPM while going down the road...

2) Got all the glowplugs replaced this summer

3) This morning the truck fired as normal, and shut down after about 5 seconds, and would not start. Figured it was the crank position fault, ran the predator and the code was "turbo overboost". Since that shouldn't cause it not to start I checked the prime and it was fine, cranked it again and it didn't start. Cleared the turbo fault and it fired right up.:confused:

It probably should be noted that I had an autostart installed last winter, and have noticed that the predator doesn't like it...I have to cycle the key several times during any operation to get it to go to the next step. I cut the data wire from the autostart to the OBDII port and that fixed the predator problem, so I'll install a switch that I can throw when I connect the predator.

Anyone else seen a "jittery" tach? What was the fix? And WTH would a turbo overboost cause the truck not to start?

Any ideas?