Cruise won't hold speed

[Racechaser]

I just took my '01 auto w/3:55's to Quebec and back to NY, and it would not hold speeds on even minor hills 0f 70-75 mph. I was towing 2 sleds on a aluminum trailer (less than 2K lbs), and I had to manually hit the "OD OFF" button to maintain speed, it would not downshift itself and would lose up to 8-10 mph. Is this a normal condition? My '96 360 gasser would downshift w/the cruise on to hold speed (and get about 8mpg).
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[mikel]

How many miles are on your truck? Is it broken in yet? My truck has about 22K and holds speed on the hills fairly well with 6-8k behind it, but it is no rocket. I didn't pull any real weight until about 12k so I don't know if mine would have pulled real well with low miles.

It may just need to be broken in, or there could be other things going on. Do you have gauges? How much boost and what EGT are you seeing?

Try checking all of the rubber boost hoses. They get loose sometimes and cause a loss of boost and power.

Hope this helps,
Mike

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'99 QC 2500 SLT Driftwood 2wd SB 24v Auto 3. 55 LSD
ISSPRO pyrometer, Walker 21468, 20,000 miles 12-19-00

-- email address removed --

Howdy Agg's!

 

[Racechaser]

Mikel, it just turned 12K before leaving on this trip. I have only a boost guage and is topping out at 15-18lbs I believe. Which hoses are you referring to? What would the EGT gauge tell me?

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'01 2500,4WD,Ext cab,sb,auto,3:55's,sport pkg(horrible cartoon decals removed),flame red,tan lthr,clearance lamps,everything but kitchen sink. 1st Diesel,never buying another gasser!

 

[Hale on wheels]

Racechaser,
We have almost identical trucks, and mine would downshift very quickly to maintain speed, since it couldn't hold speed in OD. In fact, with the cruis on I couldn't hardly keep it in OD, it kept downshifting. I think maybe something is wrong with your cruise control.

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Cody Hale
01. 5 2500, QC, 4x4,Auto
Gig'em Aggies!

 

[mikel]

Racechaser,

The boost hoses are the large rubber hoses that connect from the high pressure side of the turbocharger to the intercooler and from the intercooler to the intake manifold. I believe there are four of them giving the potential for eight places to have a leak. I have never had a problem with mine, but several others have.

I think 15-18 lbs is about right for boost. The EGT can tell you if you are not getting the fuel that the engine needs in order to make good power. Low EGT can come from many places, restricted fuel filter, the ever-popular lift pump failure, etc. I see 500-600 crusing empty at 70-75 and 950-1150 hauling A$$ or pulling a trailer.

Not knowing what kind of hills you are running against it's hard for me to say your truck shouldn't slow down, but I do know that your truck is supposed to have more power than mine and I have been happy with how mine pulls the hills around here in Texas.

 

[Racechaser]

Mikel & Hale, thanks for the tips. I'll check on both. I hate to go back to the big 5 star (more like 5 times) dealer. I didn't think this was a normal situation. I'll let you know on my findings.

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'01 2500,4WD,Ext cab,sb,auto,3:55's,sport pkg(horrible cartoon decals removed),flame red,tan lthr,clearance lamps,everything but kitchen sink. 1st Diesel,never buying another gasser!