Hi John,
You discribing two different problems.
First your adding to much fuel to quick in too high of a gear thus your here what you reffer to as spark knock. If you read Fords explantion of lugging then you will see your close to lugging the engine when this happpens. If you want to gain speed quicky, drop down a gear then acellerate. Remember a diesel is not like a gasser as a diesel needs time to wind up to a higher rpm.
Another cause is a suction air leak. The most likely place is the QD on the fuel pump suction fitting. Just replace this with a 8" long piece of 5/16" fuel line with double hose clamp on both ends.
Below is what Ford says about engine lugging in the F650/750 owners manual:
"Excessive full throttle operation below peak torque RPM will shorten engine life to overhaul and can cause serious engine damage. Operation of the engine below peak torque RPM can occur during gear shifting due to difference of gear ratios."
Second is the black smoke. I get this as I shift at low rpm to obtain maximum fuel mileage even while pulling loads. I add fuel slowly and shift at 1250rpm on flat roads thus yield great fuel mileage. 19.2mpg empty, 14.1mpg pulling 16kGCW and 17.1mpg 15k lifetime fuel mileage with pulling 16kGCW for 6k miles.
After driving with this style the Cat loads with carbon as well as the pistons and valves, so once a month I take it out on the freeway then drop down a couple gears to 2800rpm for about 15sec and during this time I will belch black smoke then it will clear to a light grey color and I'm good for another month of light grey exhaust.
/ubbthreads/images/graemlins/smokin.gif
You discribing two different problems.
First your adding to much fuel to quick in too high of a gear thus your here what you reffer to as spark knock. If you read Fords explantion of lugging then you will see your close to lugging the engine when this happpens. If you want to gain speed quicky, drop down a gear then acellerate. Remember a diesel is not like a gasser as a diesel needs time to wind up to a higher rpm.
Another cause is a suction air leak. The most likely place is the QD on the fuel pump suction fitting. Just replace this with a 8" long piece of 5/16" fuel line with double hose clamp on both ends.
Below is what Ford says about engine lugging in the F650/750 owners manual:
"Excessive full throttle operation below peak torque RPM will shorten engine life to overhaul and can cause serious engine damage. Operation of the engine below peak torque RPM can occur during gear shifting due to difference of gear ratios."
Second is the black smoke. I get this as I shift at low rpm to obtain maximum fuel mileage even while pulling loads. I add fuel slowly and shift at 1250rpm on flat roads thus yield great fuel mileage. 19.2mpg empty, 14.1mpg pulling 16kGCW and 17.1mpg 15k lifetime fuel mileage with pulling 16kGCW for 6k miles.
After driving with this style the Cat loads with carbon as well as the pistons and valves, so once a month I take it out on the freeway then drop down a couple gears to 2800rpm for about 15sec and during this time I will belch black smoke then it will clear to a light grey color and I'm good for another month of light grey exhaust.
/ubbthreads/images/graemlins/smokin.gif
