Engine/Transmission (1994 - 1998) 98 low on power

[dlefebvre]

hello all,friend of mine just bought a 98 12 valve quad cab 4 x 4 auto. Truck has about 75000 miles on it. He went to pull his 19 foot fifth wheel weighing maybe 3500 pounds. when he hits a hill in overdrive at 70 mph, the truck will not hold this speed. I was thinking maybe timing issue, I told him we could slide his plate ahead. something is not right, that truck should smoke up the hills with that little load. maybe there is an issue with the automatic? don't know how the autos behave as mine is a 5 speed. any help is appreciated. thanks.

 

[KYOUNG]

change the fuel filter!!!!!

 

[Nate]

You sure a 5th wheel only weighs 3500 lbs? That seems a bit light!

 

[dlefebvre]

the fifth wheel is a 85 Vanguard 19 foot, single axle. its one of the lighter ones made in that era. sitting beside my 02' 25 foot Vanguard, it is alot smaller. (which weighs 8000#) I never thought about the fuel filter, thanks.

 

[hansonja]

Check to make sure that the wastegate is not stuck open also check the rubbe hose that that go's to the turbo

 

[trucknut]

98 low towing power

What ever you do make sure the timing is around 15. 5 to 16. I'am assuming this 98 is a 12v. This timing adjustment will pay for itself in mpg, so well worth getting it done. Check the boost pressure--- even if it is a temporary gauge to make sure the boost is around the 22 psi mark.

The auto has a . 69 overdrive and rear end is a 3. 55 the tallest in the industry so attention to tuning details is critical. The governor plate may need a little sliding ahead to increase fueling. This Industrial engine will TOW a 3500 pound trailer around like it not even there with alittle proper tuning. Remove all cats to clear exhuast flow.



Weak lift pump problems can be heard by a ticking sound at idle. My 98 is a 5 speed which has a lower overdrive ratio of . 73. giving the truck better towing abilities in overdrive. You bought the truck, tune it, you will benifit and enjoy it.