Tach jumps to 400 with key on engine off - First start of the day
Hey guys, hoping someone has some insight, I might be onto what it is but not sure yet.
Have a 2000 F-350, 7.3 - 325k. Corporate owned truck until now. All records down to filter elements. Has new UVCH's, glow plugs, ICP and oil/top end oil.
Has a heck of a time starting regardless of temp after sitting for 8 hours. Hits on one cylinder... Then 2... Stays that way for 15 seconds then 4, but if I let off the key - stalls. If I keep the key on start for about 30 seconds while the engine is half running, it will act as though a switch is turned on at the 30 second mark and start romping on all 8 for a few seconds then idle. Quite the process.
But my main concern is when I hop in the cab and turn the key to run, the tach jumps to 400 rpm and slowly drops as I wait for the glow plugs. It only does it on the first start of the day.
How long does the stock IDM usually last? I believe it was the IDM that controlled to signal to the PCM for the tach, and if I'm having a hard time starting and the tach is showing 400 rpm just with the key on... Could it be the IDM on its last leg?
Insight would be great, thanks in advance.