Truck won't hold a constant speed

Asked by Apr 23, 2017 at 09:58 PM about the 1993 GMC Sierra C/K 1500

Question type: Maintenance & Repair

While I am driving down the road above 40 mph I
always have to accelerate because it won't keep a
constant speed and when I do accelerate
sometimes it will sit there at the same rpm and all
of a sudden jump up to high rpms and other times
it seems as though it doesnt want to accelerate to
me it seems as it would be either the trans is going
bad or the tps is going bad I checked the trans fluid
and its a good color and it doesnt smell burnt

4 Answers


93 is OBD 1 you may need to find a shop that still has some of the old test equipment for data scanning, it is possible you have a dead spot in the TPS range sweep or maybe even a fuel pressure or flow problem.

I don't have any dash lights on I do have cruise control but it doesnt work anymore I had the trans rebuilt also about 3 years ago it now has about maybe 25000 miles on it give or take some but when it was rebuilt it also got a rebuilt torque converter

My reason for thinking it was the tps was because I would push down on the pedal and it wouldnt do anything so I would keep pressing down until it did and thats when it would jump up into high rpms

So if the motor were to be bad or not in good shape it could cause that lagging feeling to feel even worse than what it should be my #8 cylinder has leaking valve guides thats why im asking

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