I have a 2000 Chevy 2500HD with a 6.5L Diesel. Customer has had work done previously (including "40 HP injectors, bigger turbo, injection pump, optical sensor, pmd(and relocated) and a tuned ECM.) We've been fighting a p0303 - cylinder 3 misfire. I've replaced injector, and fuel filter. Some change and smoother idle and a little more power. Now the computer stores the same code but no mil light. Live data shows timing degree to be around -2° and the timing of pump to be the same as for actual and desired ( anywhere from 11° to 13° but always the same no matter what's commanded ) I'm not a huge diesel tech and I don't want to blow his money down the drain on just guessing. I'm thinking the pump may be bad but not sure. Also on live data watching the missed references for crank and injection pump the injection pump shows a miss around 1500 rpm and lower and the crank at low rpm occasionally (hence me thinking its the pump and the crank reference is in a way confirming it?)

Tags: P0303 , 6.5_diesel , gm , gm_misfire

Also forgot to mention, the crank sensor was replaced with all other work.