Cruise Control Problem?
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Cruise Control Problem?
I've got a new 04/04 F250 Lariat SC LB 4x4 PSD. No mods. 1200 miles. Factory oil changed at 1100 miles to Chevron Delo 400 15W-40 (13.5 qts).
I was driving at 55 MPH with cruise control today and came across some steep hills, none of which was any higher than 150 feet (sort of like ski mogols). Going up, no problem. But on the dowside, as the truck picked up speed (coasting) past 55 towards 60-65 MPH, the RPMs on the motor dropped to 500 PM, kind of like the transmission disconnected or went into neutral. Then as the truck started up the next hill, the speed would drop off to 40-45 MPH before the cruise control would "wake up" and "stomp" on it, dropping the tranny down two gears and accelerating like a scalded cat till it got back up to 55-57 MPH. Vehicle had been driven at 55 for over 75 miles, so trans and engine were at operating temp.
Is this normal behavior for the PSD with the 5-speeed auto trans? My '01 F250 with the V10 never behaved this way.
I was driving at 55 MPH with cruise control today and came across some steep hills, none of which was any higher than 150 feet (sort of like ski mogols). Going up, no problem. But on the dowside, as the truck picked up speed (coasting) past 55 towards 60-65 MPH, the RPMs on the motor dropped to 500 PM, kind of like the transmission disconnected or went into neutral. Then as the truck started up the next hill, the speed would drop off to 40-45 MPH before the cruise control would "wake up" and "stomp" on it, dropping the tranny down two gears and accelerating like a scalded cat till it got back up to 55-57 MPH. Vehicle had been driven at 55 for over 75 miles, so trans and engine were at operating temp.
Is this normal behavior for the PSD with the 5-speeed auto trans? My '01 F250 with the V10 never behaved this way.
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Postmaster
Joined: Aug 2003
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From: Central Texas
The auto tranny won't "engine" brake unless you are in tow/haul mode. Sounds normal. When I hit hills like that, I take it out of cruise control for that reason. I can anticipate the need for throttle better than the cruise control.
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Joined: Aug 2003
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From: Eastern Oregon
I don't have this problem and travel roads that sound similar. I'll be doing it again tomorrow and will try to pay closer attention. But I'm also doing about 65 too, so that could be the difference.
Postmaster
Joined: Aug 2003
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From: Central Texas
I was driving north on 95 from Blythe to Needles. I recall a stretch like you describe. I don't recall the downhill getting too fast as I think that was 65. The uphill on cruise control was beggining to irritate me so I went manual and it was much smoother. We as humans will anticipate the need for more fuel. The cruise control waits until the speed starts dropping off and over compensates for it.
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From: Eastern Oregon
rstephenw
On my way to work this morning I set the cruise at 62. All throughout my trip, about 45 miles, I went down and up about 6-7 times with hills of varying height and length. Except for 1 hill my speed never varied nor my RPM's. On 1 hill, the steepest, it called for more fuel, RPMs went up a tad, but never changed gears.
But, my hills and yours could vary well be different. But this was my experience.
But, my hills and yours could vary well be different. But this was my experience.
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