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Junior Member
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20 Posts
Discussion Starter #1
I have a stock 01 7.3. I had the trans rebuilt recently by a local reputable trans shop. I went with a heavier duty than stock torque converter and told him I had a 30' camper and may add a plow(he asked these questions) and built it accordingly to be stronger than stock. The truck runs great and has no problems.

The tranny works and shifts well...but...when I get on the highway, which from my exit there is no phase in lane, you just jump right out into traffic, I have to basically floor it to get out of the way.

When I stomp on it to get moving, the engine revs all the way to 3200/redline before it shifts, same for all gears. So basically the power falls flat on its face and acceleration is terrible. All other driving conditions the truck shifts fine and is great. Only when I floor it. I replaced the speed sensor in the rear end and it made no difference. The tranny before it quit, behaved in exactly the same manner. It actually accelerates faster at 3/4 throttle because it shifts earlier.

Does anyone know why this is happening and what I can do to have it shift at about 2800rpm at full throttle?

I have not had time to go back to the tranny shop yet. But I wanted some useful background info from you guys before I go, in case there is something I can do about it first.

Thanks, -Dan
 

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Junior Member
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20 Posts
Discussion Starter #2
I think I should have been a little more specific. It does not rev to 3200 before the truck moves. It takes off just fine and pulls well through first gear, but where I think it should be shifting to 2nd at about 2800, it revs right past that, power falls off dramatically, hits 2nd gear at 3200 and rpm drops to about 2700, tries to pull again but is already at the end of the power curve and power is falling off again up to 3200 before it hits 3rd. So as far as trying to accelerate quickly into traffic, it does not work so well. Verses my old 99 7.3 6-spd that I could shift out at 2800, drop to 2300, and pull hard again through the power curve.

How do I fix this? Does a tuner allow you to select specific shift points?
 

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Stuck in Commiefornia...
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1,296 Posts
It could be a number of things but being an electronically controlled transmission it's relying upon the load and throttle input from the driver to determine the shift points if you have a bad map sensor a bad throttle pedal or an issue in the tuning that you're running if you're running to any of those things could be the source of your issue.

I just tuned my truck, an early 1999 7.3, because the shift from third to overdrive wasn't occurring until 55 to 60 mph and should've been occurring at 40 to 45 under the amount of throttle input that I was giving the problem was exclusively tuning issue there was nothing mechanically wrong with my truck. Running a canned SCT performance tune completely resolved the shipping issues for my truck and it now shifts at the desired 40 to 45 mph under light throttle the way I want it to.


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