dougx

Here is one for you, driving me crazy. 2003 2500 hd 6.0L. No egr on '03. Bought truck 4 years ago,56000 miles, mostly stored and ran well. Started few times each year. Then one day would not start. Found fuel pump bad and bad fuel in tank. pump screen rotted off. Pump replaced with new filter. Started up on the first try. Few days later developed miss. Tried injector cleaner. No change. Ran scan tool. Only code po300 , misfires in Cylinders 2,4,6,8 were the worst #4 really bad, also the plug was fouled. 1,5,7 minimal #3 fair amount of miss, replaced the plugs and tested wires.Fired up the engine , still felt the same, #4 very wet. Scoped for all coils firing, Swapped 2 coils no change. pulled injectors on even bank, looking for one that did not shut off. Bench test showed ok @75psi. When running fuel, ration is right at 14.6. Did compression test all about 145 psi. Cleaned map, and throttle body as well. All sensors seem to read ok. Runs with a lot of power smoothly and po300 goes out temporarily at speed and uphills even on 7 cylinders apparently.. Lot of info, what's left What is going on??????? Thanks for any help....