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Discussion Starter · #1 ·
I limped my tranny for my first time ever tonight. I was still in WOT (i think thats what you call it, full accelleration) going into 5th gear and it limped on me. The two codes i got were po700 and po735. I had my superchips programmer on performance, its around +110 i think. My trannsmission was cold and i wasn't thinking. I was wondering now if its gonna limp on me alot easier now because i don't have the money for a built trannsmission on a truck with over 200,000 miles. Or if getting efi live would be better because i've been wanting to buy that for a while now. If i don't shift into 5th in WOT anymore, will I be fine? Any help is appreciated.
 

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yes it only gets easier to limp each and every time, good efi tuning will help but anytime your wfo going into the higher gears it'll take a toll on a stock trans with tunage
 

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Discussion Starter · #3 ·
It was in tow/haul mode too, if that means anything... I was plannin on gettin Rob's tuning soon probably. So i just need to start being more careful and, if racing, let off some when shifting into higher gears?
 

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It was in tow/haul mode too, if that means anything... I was plannin on gettin Rob's tuning soon probably. So i just need to start being more careful and, if racing, let off some when shifting into higher gears?
everytime you let off for a shift put a dollar or two in an envelope for your tranny you are gonna need! here is a thought don't race unless your running a stock tune! yah Robs are a good choice.

Ive read many different threads on tow haul mode I don't know what to believe! one person says it drops line pressure and the next guy says it doesn't............
 

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2008 Silverado 2500HD
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Why were you in tow/haul mode? Don't do that. Use tow haul if your pulling over 7500 pounds on a STOCK tune with a STOCK tranny. If you want to run a decently hot tune, dont use tow haul. Its not designed for hard driving as it is only switching tunes of the TCM, not the ECM. Makes your shifts more firm, less defuel, and the line pressure does drop.
 

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Discussion Starter · #6 ·
I don't know why i was in it really. I'm new to Duramax and don't know too much really. I'll definitely not use tow/haul mode again. That was first time, as an experiment. Dumb idea i see now...
 

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Thats okay. Without tow haul that tune probably wouldn't have limped your tranny. 5th gear is the weakest point in your transmission, so on your biggest tune, be careful shifting into 5th, make sure to let off it a little, and while in 5th try not to give it too much throttle. Hold down your tow/haul button to turn overdrive off, and have fun on your big tune.
 

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Discussion Starter · #8 ·
So I should be fine if I'm a little more careful from now on? And, sorry if i sound like a noob here, when do I hold down tow/haul?
 

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Under WOT TC tries to lock anyway. Tow/haul just lock it earlier

Line pressure drops with lock up not tow/haul
 

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So I should be fine if I'm a little more careful from now on? And, sorry if i sound like a noob here, when do I hold down tow/haul?
Holding down Tow/haul for few seconds locks out OD. You never need to hold it down.
 

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Also be careful as to not go into tow haul unless your in Park/Neutral. You'd probably be fine in drive but I've found its better safe than sorry. rd05lly is correct just hold the button down for a few seconds and your "O/D Off" light should come on.
 

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Discussion Starter · #12 ·
When would i want to shut O/D off? When i'm pullin trailers and stuff it would make sense, but any other time?
 

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When you feel like getting on it. Like I said, 5th gear is the weakest point. So if you line up next to a gayboy in a civic at a traffic light, hold that thing down. Towing not a bad idea either. You can turn overdrive off while moving as well. Just don't do tow haul mode while moving. We tow over 20,000 with our 07 and have not once used tow haul mode.
 

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Discussion Starter · #14 ·
That is exactly why i didn't want to play it safe and drive/race in a stock tune because when i pull up next to a "gayboy" in a ricer or flowerstroker or cummins, i need to be able to dominate! So i'd be pretty safe drivin around in performance all the time? at least until i get EFI :) Then i can start out in higher powered tunes and switch to a lower one once i get into the higher gears too once i get efi and a dsp5 switch... And i'm gonna try shutting overdrive off instead of tow/haul next time i'm towing too!
 

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When you tow, tow on no more than a 50hp tune. My 01 never tows with any higher tune than that and the 07 tows on all stock tuning. As for the rice boys, even a 50hp tune will beat em.
 

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Discussion Starter · #16 ·
I do set it on tow when i tow, which is a +50 tune... but yea, thanks for all your help I'm always happy to learn more I'm only 17 (i bought and pay for my own truck) so i'm new to alot of this
 

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You've come to a great place for information and answers to questions. Feel free to PM me if you have any further questions.
 

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Use tow/haul when towing only lock out OD when on back road and you don't want it shifting between 4 and 5 or racing and you don't want it to go in 5 on WOT. Locking out 5 on highway towing you would be turning high rpms.


Sent from AutoGuide.com Free App
 

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Discussion Starter · #19 ·
Sweet i'll definitely do that when i race. All overdrive does is stop it from shifting into 5th right and can you turn overdrive back on when you in high rpms in 4th and need to shift up, just make sure to let up before you do?
 
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