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Okay previous problems having been addressed, this is the latest. When you kickdown on the accelerator, as if passing or climbing a steep hill, the RPMs go up but the speed doesn't. If you accelerate slowly, all is well. The transmission guy says it's not the transmission. Engine guy changed the fuel filter (not that dirty) and the plugs and we ran about 500 miles of Sea Foam through it. Seemed to help at first. but back to square one about 1K miles later. The truck is in real good shape so I don't mind spending some money on it. The cost of a new one gives me apoplexy.
"Be sure you're right. Then go ahead." Fess Parker as Davy Crockett
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Joined: Jan 2001
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Campfire Ranger
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Campfire Ranger
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I don't see how the rpm's can go up with speed not changing unless either the transmission is downshifting, the clutch is slipping (if manual) or the torque converter is slipping (if auto)
If the engine is simply getting louder but making enough power to accelerate that's a different issue. Might be worth doing a compression check to see if the engine is still healthy, also check the plugs to see if any of the cylinders look like their running off.
How is oil consumption?
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Campfire Regular
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Campfire Regular
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I can't imagine a transmission guy dismissing the transmission and not letting you know about a clutch, transfer case or torque converter. I had a suburban with a manual transmission and when the clutch went out it acted just as you describe. There weren't many manual transmissions in the late 1990's so I suspect the converter or transfer case. Physics says it's impossible to gain RPM but not speed unless something between the engine and tires is slipping. You don't hear your differential sounding like a rock crusher do you?
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Campfire Outfitter
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Campfire Outfitter
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Check the kick down cable they stretch.. Check the timing .Could also be a fuel delivery system problem. I had to change my fuel pump last year due to cutting out on my 2000 Silverado
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Campfire Regular
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Fuel pumps were an issue in that model year - I speak from experience, only in my case they WANTED to change out the transmission π. Kind of a pita , pump is in the tank.
My bet is the pump
Good units
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Campfire Ranger
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Campfire Ranger
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Thoughtful ideas. Thanks for the suggestions. It's auto transmission. When I try to accelerate fast, the RPMs go up, the noise level goes up but we don't travel any faster. I'll have to try this again but I tried manually dropping a gear and, IIRC, it was more normal. Reluctant, somewhat, to try it again when the RPMs are racing. The truck uses less than a quart of oil between changes, usually around 5,000 to 6000 miles. Differential is quiet. 50,000 miles ago a very similar problem was cured with a fuel filter change. Tried it again didn't fix it. I agree something must be slipping or not engaging. I was surprised by what the transmission guy said. On the other hand their neighbor had just shot and killed himself before I got there. They may have been a bit distracted although it didn't seem like it. After all, they are transmission guys. Everything is "normal" unless I really kick it pretty hard.
"Be sure you're right. Then go ahead." Fess Parker as Davy Crockett
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Campfire Kahuna
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Campfire Kahuna
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This sounds like a rental car I had a few years ago, a Nisson Altima. If I needed to accelerate in a hurry, it would drop 2 gears, the engine would race and it would veeery sloooowly accelerate.
βIn a time of deceit telling the truth is a revolutionary act.β β George Orwell
It's not over when you lose. It's over when you quit.
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Campfire Tracker
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Campfire Tracker
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I had that with a bad aftermarket torque converter in a 2001 corvette, A Yank torque converter fixed it.
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Campfire Ranger
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Just FYI
Took it into the shop today. On the way it was misbehaving as per usual. The head guy drove for a test and it ran perfectly. Ran great on the way home too. Now I have to wait until it acts up again.
"Be sure you're right. Then go ahead." Fess Parker as Davy Crockett
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Campfire Oracle
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Campfire Oracle
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Hate those intermittent problems.
Good luck.
If you take the time it takes, it takes less time. --Pat Parelli
American by birth; Alaskan by choice. --ironbender
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Campfire Ranger
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Campfire Ranger
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Have a smart phone? Video it the next time it acts up. Show tach and speedo. Then you have something to show mechanic.
Parents who say they have good kids..Usually don't!
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Different year but had a suburban a 93 that was acting similar. Thought it was the tranny. Normal driving was fine but when getting on the freeway or anytime I really had to put my foot in it all show no go. Thought for sure the tranny was slipping. Would drop a a gear and things would be fine or it would eventually slip into the next gear and all was fine. Ended up being the speed sensor for the tranny. Tranny was not shifting correctly.
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Campfire Tracker
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Just FYI
Took it into the shop today. On the way it was misbehaving as per usual. The head guy drove for a test and it ran perfectly. Ran great on the way home too. Now I have to wait until it acts up again. intermittent sounds like an electrical problem...maybe something with the torque converter lockup...........
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Campfire Regular
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I had a 1996 GMC truck that did that. Step on the gas pedal and it would rev up but didn't go any faster. Let off the gas and then apply slowly and it ran fine.
It was the 700R4 transmission that was causing the problem.
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Campfire Tracker
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Campfire Tracker
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I had a 1996 GMC truck that did that. Step on the gas pedal and it would rev up but didn't go any faster. Let off the gas and then apply slowly and it ran fine.
It was the 700R4 transmission that was causing the problem. I had the same deal with a '96 (305 ci), only it would cough/sputter whenever the accelerator was pressed. If you feathered it lightly, you could eventually get it up to speed. 'Twas the plug wires. FC
"Every day is a holiday, and every meal is a banquet."
- Mrs. FC
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Campfire Outfitter
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Just FYI
Took it into the shop today. On the way it was misbehaving as per usual. The head guy drove for a test and it ran perfectly. Ran great on the way home too. Now I have to wait until it acts up again. You should take it to GM spend the 60 bucks and have it scoped. They will tell you within a couple minutes exactly what is wrong.. It will save you time and money in the long run. I'm the last guy to recommend a dealer but it will eliminate the headache of guessing. Then do the repair yourself or take it to a mechanic you trust.
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Campfire Tracker
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Could the catalytic converter be clogged ?
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That's what's I would bet on also
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Campfire Ranger
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Campfire Ranger
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Come on guys. He says rpms increase but truck does not speed up. If he is right, everything back to the flywheel/flexplate is working fine, There is slippage somewhere between the end of the crank and the tires on the pavement. Most likely this is an automatic, if so, thats the prime suspect. It perfectly describes a manual clutch about to die.
Parents who say they have good kids..Usually don't!
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