Turtle n Peeps wrote:
What's the problem? You ran out of horsepower. Running a big box up a hill takes a lot of horsepower. 45 MPH going out a big hill is pretty good. No CEL no problem.
Assuming this is an E450....mine did the same thing. Even on small hills......when the cruise was set. Anticipating the hills and gaining an extra 5 MPH BEFORE the actual grade can help a lot; this gets your foot "in it" early.
Long or steep hills, that's just the way gravity and drag works.
My replacement rig does that too....some.....and it has the big GM Workhorse chassis.
Now.....I got the electronic "retune" for my 450. It helped some. I could leave the cruise set until the terrain got somewhat worse.
My 450 is now gone and the tuning kit is for sale, at less than half the original price. Look it up in threads on here.
HOWEVER.....there was one minor annoyance:
With the "re-tune", as the engine pulled harder going up hills, it lost enough engine vacuum that the A/C output was directed to the windshield vents. It returned to normal after the hill. This did not happen when stock.
