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Junior Member
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348 Posts
Discussion Starter #1
Driving 2003 f550 with 6.0 and truck seams to run ok but when I go to go up a small hill I loose all power and speed like going from 70mph to 5mph in about 30 seconds but I still have 2,500 rpm I shift into 1st 2nd and 3rd gear and trans shifts and rpm is good but truck will not go over 10mph untill I shut off the truck and start it again and it will run good untill it goes back up a small hill and starts over again. What should I do
 

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Stuck in Commiefornia...
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1,296 Posts
Ok, so you're saying you're maintaining 2500rpm but the truck will slow from 70 to 5mph? There is something wrong with the transmission or the PCM or both. Have you checked the fluid level? Do you know much about the truck, like how many miles, could it have been services with the wrong fluid? The truck should have a trans temp gauge in the cluster. Also, there should be a check engine light on in the cluster. Pull codes with your SCT device from the truck in your signature, engine light of not.
 

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Junior Member
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348 Posts
Discussion Starter #3
Ok, so you're saying you're maintaining 2500rpm but the truck will slow from 70 to 5mph? There is something wrong with the transmission or the PCM or both. Have you checked the fluid level? Do you know much about the truck, like how many miles, could it have been services with the wrong fluid? The truck should have a trans temp gauge in the cluster. Also, there should be a check engine light on in the cluster. Pull codes with your SCT device from the truck in your signature, engine light of not.
No cell or cods. Transmission is full of fluid truck has 150k and all fluids and filters are good use only motorcraft. Transmission shifts fine I can count all gears just when it goes to go up a hill it just has no power I have tried to shift the truck up and down but only thing that changes is the rpm still no power
 

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Senior Member
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3,051 Posts
So is the transm slipping or is the engine power just falling on it's face?

If it's the engine power falling off, could be turbo issue, ficm issue, fuel filter issue.

Harry
 

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Stuck in Commiefornia...
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The descriptions of what's going on here are pretty vague. With a lack of any codes, it had to be something the truck is unable to recognize as a fault. The only time my 6.0 ever had a complete lack of power while running was when the EGR valve was stuck open. Almost got T-boned it's was so bad. Good luck. I'd strongly suggest seeking out someone with AE or a high end scan tool to monitor data and see what's going on.
 

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Junior Member
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348 Posts
Discussion Starter #6
Trans does not seam to be slipping just lack of any power. Truck gas egr delete in it so I guess I am going to pull turbo and check and also check ficm and go from there.
 

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Junior Member
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348 Posts
Discussion Starter #7
Well found that truck had a bad icp o leaking out of it and turbo was dirty and stuck so I replaced icp and harness, cleaned turbo and changed fuel filters and drove truck and same thing happened except this time I could te when truck shifted from 3rd to 4th gear it seamed not to go into 4th and stay in between gears and truck slowed down from 50 to 5 and died took about 5 minn to get it to start again. So I don't know maybe a trans problem or coult it be a toque converter issue becuses the truck still acts like it is under a load but it just has no power:stars
 

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Junior Member
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348 Posts
Discussion Starter #8
Ok been driving truck around today and truck runs great 55 mph and under and gears 1-4 but if truck goes over 55 mph and tries to shift into 5 gear truck pretty much falls on it face in power untill truck dies wait a few min truck will start again and run great as long as I stay under 55 mph and it does not try to shift into 5th gear or I am stuck on the side of the road. Truck still has no cell or codes.
 

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Stuck in Commiefornia...
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You need to get someone with proper diagnostic equipment to take a look at the truck and watch what's going on while you replicate the situation for them so that they can identify it and keep you from spending money on things that aren't broken.
 
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