6.4L Power Stroke Engine and DrivetrainDiscussion of the 6.4L Power Stroke diesel engine and drivetrain in the 2008 Super-Duty trucks. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.4L Power Stroke engine.
Driving around 70mph, floor it and there is no downshift. Thought my '04 would shift. Is this normal or is the PCM programmed not to do stuff until a certain milage?
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'08 F350 Lariat DRW CC LB Job 3 Black/Silver
towing a '07 Raptor 3712TS toyhauler
with a '02 Kawasaki Nomad Dresser in the garage
Did you have a trailer hooked up during the test? Maybe the computer did not see a need to downshift to attain the desired results. Did you have Tow/Haul selected? If not, try the same test with it selected.
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Line-X bedliner, heavy duty floor mats
2003 Sunline F281SR(weekend getaways)
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I would do the math if I knew what RPM he was turning at 70 MPH. All that needs to be done is divide the RPM by 0.712. That will give the RPM in 5th gear.
__________________ Mark
Former Automatic Transmission Engineer 1988-2007
I have the 4.10 rear. RPM's??? I know on my 3.73 it was just at 2000. With the 4.10, probably around 25-2700. Maybe some of it has to do with the quietness of the engine. Would really hear the 6.0 wind up.
__________________
'08 F350 Lariat DRW CC LB Job 3 Black/Silver
towing a '07 Raptor 3712TS toyhauler
with a '02 Kawasaki Nomad Dresser in the garage
I have the 4.10 rear. RPM's??? I know on my 3.73 it was just at 2000. With the 4.10, probably around 25-2700.
2000 * 4.10/3.73 means the new truck will be at 2200 RPM.
Now if you were to downshift from overdrive to direct drive, your RPMs would be 2200/0.712=3100 RPM. Since it upshifts at a few RPM higher than this, it isn't going to downshift.
If you really are at 2700 RPM in overdrive you would be at 3800 RPM in 5th gear.
__________________ Mark
Former Automatic Transmission Engineer 1988-2007
Thanks. I need to look at the RPMs to see where I really am. Maybe my 6.0 didn't shift? I can sort of see why it wouldn't shift. It is right in the powerband and does go. Just trying to get used to the truck before towing with it so I know what to expect.
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'08 F350 Lariat DRW CC LB Job 3 Black/Silver
towing a '07 Raptor 3712TS toyhauler
with a '02 Kawasaki Nomad Dresser in the garage
Figured I would give a follow-up. When doing 60ish, open her up and she downshifts till around 70. From 70 on, top gear. Deceptively quick up there. Just so quiet, I was used to the racket from the 6.0.
__________________
'08 F350 Lariat DRW CC LB Job 3 Black/Silver
towing a '07 Raptor 3712TS toyhauler
with a '02 Kawasaki Nomad Dresser in the garage
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Automatic Transmission Engineer 1988-2007
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