Compression Ignition Addict
Join Date: Oct 2010
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I agree ^^^^^. Why not just leave it on. At highway speeds. it's going shift up into 6th gear anyway. So you are not gaining any MPG.
The tow haul mostly affect the shift points in the lower gears. Instead of upshifting at 1600rpm, It will hold the gear and upshift at 2200 rpm. Keeps you in the powerband.
I especially notice this around town where I'm in a 30 mph type of street. Cruising along at 30 mph in Tow/Haul holds 2nd gear at 2000 rpm. If I turn Tow/Haul off it upshift to 3rd and drops to 1500 rpm. When I need to step on the go pedal ( say a light just turned yellow and I want to clear the intersection) Without T/H, The tranny has to down shift to second when step on. In T/H it is already in the right gear and already in the powerband with turbo spooled up.
If you turn T/H off on the hiway, Your tranny just tries to hold 6th gear longer, causing the engine to lug on grades, where T/H would down shift a little earlier getting you into the power band. You EGT will stay lower at higher RPM than lugging up the grade in a higher gear. Watch your gauges. I've seen this many times where I forgot the T/H and found myself pulling a 5% grade at 70 mph in 6th gear at 1600 rpm with my 13,000lb GN horse trailer, But my EGT run up to 900°. Touch the T/H button, the tranny downshift to 5th gear, I gain 400-500 rpm, still staying at the same speed on the cruise, But my EGT drop 300°.
2015 F350 CC SRW LWB Lariat, Leveled, BAKflip, Ultra Predator wheels with Toyo A/T 295/65R20, Firestone Airbags and onboard compressor
2011 F350 CC SRW LWB Lariat - Gone
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