1999 d12 ecu problem

Truck is lacking alot of horsepower, had dyno done today first time it was at 330hp second time was at 170 hp, engine is rated at 425hp. Dealer cannot figure it out they said they cant read the ecu. just wondering if anyone has ever had this problem. Dealer said possible wiring harness and ecu.

 

Ok i will check it out. Thank you

 

Checked out the wiring, everything seems ok. Ran a diagnostic and engine had no faults, transmission and brakes not responding. I disconnected the coolant sensor and no codes for that, I am stumped this truck runs great but is losing power intermittently. I don't know why Volvo could not read anything on the computer I was able to scan it fine today. Could this be a fuel problem ?

 

Its a plug wired into the harness that plugs into the backside of the coolant tank. Could it be that the trans and abs have bad connection somewhere and are causing these problems. I also noticed when going through the harness i have a kysor dcm box with 2 plugs in it, i thought that if you had a ecu you you wouldnt have a kysor box. Would you be able to email me the diagnostic flow chart me and my mechanic just want to start from the beginning and the volvo dealer is being of no help what so ever its a 1998 d12. scottyfoxx2000@yahoo.com thanks for your help.

 

Thank you, what do you think could be the cause of this? What are the specs for fuel pressure? Thanks

 

In your experience have you seen this happen with these trucks?