do i need a TCM tune?

Dirtymaxx03

Dirtymaxx03

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Aug 4, 2009
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my truck is hanging the 4-5 shifts. I go WOT 1st-4th shifts beautifully then it hangs the shift to 5th. i gotta let out (quite a bit) then it will catch 5th and take off again. Is this something a TCM tune will fix? or do i have a different problem....
 
Dirtymaxx03

Dirtymaxx03

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i also noticed a CEL came on when it hung up. but im about 98% sure its a p0802 that ive been dealing with for a few weeks. is that related to the hangin shift? bump
 
TrentNell

TrentNell

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with out seeing a log of the fueling during the shift it is impossible to know the answer , short answer is no a tcm tune wont fix the issue , long answer is a log will tell for sure . Is there another code with the p0802 ? the p0802 code is really just saying the mil was requested to be turned on by the tcm .
 
Chevy1925

Chevy1925

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Dirtymaxx03 said:
i also noticed a CEL came on when it hung up. but im about 98% sure its a p0802 that ive been dealing with for a few weeks. is that related to the hangin shift? bump
Click to expand...

dropping too much fuel rail pressure will make it hang as well. like trent said, log will tell all as well as the other codes
 
Dirtymaxx03

Dirtymaxx03

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TrentNell said:
Is there another code with the p0802 ? the p0802 code is really just saying the mil was requested to be turned on by the tcm .
Click to expand...
there could be...i knew my truck was throwing the 0802 so when the light came on i assumed thats what it was. but it could be a fuel limp code....
Chevy1925 said:
dropping too much fuel rail pressure will make it hang as well. like trent said, log will tell all as well as the other codes
Click to expand...
im gonna log rail pressure tomorrow. How much would you say is an "allowable" drop?
LBZrcks said:
Are you sure it's hanging? Or could it be the converter not locking?
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honestly i dont know. all i know is when it comes time for it to switch to 5th it just stays at the shift point, untill i let out to let it shift. I'm gonna throw a new fuel filter on tomorrow as well. Im willing to bet thats the problem, my current one has 9,000 miles on it

im gonna try to post up a video of it
 
JoshH

JoshH

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TrentNell said:
Is there another code with the p0802 ? the p0802 code is really just saying the mil was requested to be turned on by the tcm .
Click to expand...

You sure about that? I always thought the TCM mil request code was P0700. I had never heard of a P0802 code before, so I looked it up. P0802 Trans Ctrl Sys MIL Request Circ/Open

CONDITIONS FOR SETTING THE DTC
The ECM is detecting an improper voltage level on the TCM MIL request circuit
 
LWATSON

LWATSON

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Jul 30, 2008
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I would do some testing on the lift pump. I have mine on a toggle switch and if I forget to turn it on my truck acts exactly like this.
 
Dirtymaxx03

Dirtymaxx03

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JoshH said:
You sure about that? I always thought the TCM mil request code was P0700. I had never heard of a P0802 code before, so I looked it up. P0802 Trans Ctrl Sys MIL Request Circ/Open

CONDITIONS FOR SETTING THE DTC
The ECM is detecting an improper voltage level on the TCM MIL request circuit
Click to expand...
couldnt a bad connection at the TCM harness cause the code? or a bad nbsu?
LBZrcks said:
I haven't got one yet, but I'm waiting on some to come in. I had the same problem as you, then I went to a standard ML converter and it still happens but not as much.
Click to expand...
what lock up box do you suggest? assuming thats the problem im gonna need one. id rather buy a lock up box then another cp3
 
Dirtymaxx03

Dirtymaxx03

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LWATSON said:
I would do some testing on the lift pump. I have mine on a toggle switch and if I forget to turn it on my truck acts exactly like this.
Click to expand...

my lift pump is turned up (maybe a little to high) and i can hear it loud and clear...
 
L

LBZrcks

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Jun 2, 2007
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Dirtymaxx03 said:
couldnt a bad connection at the TCM harness cause the code? or a bad nbsu?
what lock up box do you suggest? assuming thats the problem im gonna need one. id rather buy a lock up box then another cp3
Click to expand...

Bens.

Do some more testing and log it and see if the converter is locking or not. Your truck seems to be doing exactly what mine does, so I would be willing to bet a box would solve your problem.

I've tried various TCM tunes trying to command lockup earlier and they didn't help the lockup problem.
 
Dirtymaxx03

Dirtymaxx03

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Aug 4, 2009
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LBZrcks said:
Bens.

Do some more testing and log it and see if the converter is locking or not. Your truck seems to be doing exactly what mine does, so I would be willing to bet a box would solve your problem.

I've tried various TCM tunes trying to command lockup earlier and they didn't help the lockup problem.
Click to expand...

i'm gonna log it tomorrow evening, im hoping its a converter lockup problem.

could the converter not locking cause the p0802 code im getting
 
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