Allison 5sp: 06 Duramax converter lock up

[Jncrawford18]

I have a 2006 GMC 3500 crew cab 4wd dually LLY with the 6 speed Allison trans with the manual shift option I've put a 5" magnaflow straight pipe exhaust on it with a 3" mbrp down pipe and a bully dog gt tuner the issue I'm having normal driving the truck does fine towing the truck does fine the tuner tells me that the converter locks up in 5th and 6th gear now if I decide I want to mess around and I get on it in my tow tune or performance tune 1st and 2nd it takes off hard but 3rd and 4th it falls on its face and picks back up in 5th and 6th I don't mess with the extreme tune cuz I don't have a lift pump or anything else done to the engine any advice would be greatly appreciated thanks


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[zakkb787]

I have a 2006 GMC 3500 crew cab 4wd dually LLY with the 6 speed Allison trans with the manual shift option I've put a 5" magnaflow straight pipe exhaust on it with a 3" mbrp down pipe and a bully dog gt tuner the issue I'm having normal driving the truck does fine towing the truck does fine the tuner tells me that the converter locks up in 5th and 6th gear now if I decide I want to mess around and I get on it in my tow tune or performance tune 1st and 2nd it takes off hard but 3rd and 4th it falls on its face and picks back up in 5th and 6th I don't mess with the extreme tune cuz I don't have a lift pump or anything else done to the engine any advice would be greatly appreciated thanks


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First off, only post in one section of the forum. Double posts have to be moved and deleted by mods and they don’t enjoy doing it.

Second, throw the bully dog in the trash. It’s causing more issues than it is doing you good. There’s a reason everyone here uses EFILive tuning, and if you MUST use a can tuner get a PPE tuner. But with the price of EFI now, there’s no point in anything else.

 

[Mike L.]

I like your style.:thumb:

 

[zakkb787]

I like your style.:thumb:

Was that for me or the OP Mike?:angel:

 

[Chevy1925]

Oh it’s for you, Zak

 

[gmduramax]

It’s probably dropping rail pressure

 

[Jncrawford18]

My pressure is holding strong according to my gauges

 

[2004LB7]

How's your boost look throughout the run? Will the converter not lock in 3rd & 4th?

 

[Jncrawford18]

Have to pull up my boost on my monitor so I can check it out but no my converter doesn't lock until 5th and 6th

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[zakkb787]

Possibility the trans is slipping? These trucks won’t lock up until 5th unless you’re in tow/haul

 

[Jncrawford18]

That's almost what it feels like but in the stock tune it pulls strong and it pulls 15,000 lbs without a problem so I'm a little lost

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[zakkb787]

That's almost what it feels like but in the stock tune it pulls strong and it pulls 15,000 lbs without a problem so I'm a little lost

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Stock tune it’d feel fine because it’s stock power. With a 200 tune in my lb7 stock trans it’d limp easily. Even with a 100 horse street tune. But stock and 30 the trans felt fine. Not sure how a bully dog works but may be keeping it from limping.

 

[Bdsankey]

Stock tune it’d feel fine because it’s stock power. With a 200 tune in my lb7 stock trans it’d limp easily. Even with a 100 horse street tune. But stock and 30 the trans felt fine. Not sure how a bully dog works but may be keeping it from limping.

God I know this struggle. My trans in my tow rig hates life on anything above 75hp. Put it on the big tune to pass you better be ready for a pedal fest to keep it from limping.

 

[Jncrawford18]

Sounds like that might be the issue because what you just described described it to a tee

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[Jncrawford18]

Yeah tell me about it I just read about the transgo jr and it correcting this problem being able to handle up to 500hp anybody have any experience with this

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[Mike L.]

Yeah tell me about it I just read about the transgo jr and it correcting this problem being able to handle up to 500hp anybody have any experience with this

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Transgo jr is a band aid unless used during a full build.

 

[Bdsankey]

Yeah tell me about it I just read about the transgo jr and it correcting this problem being able to handle up to 500hp anybody have any experience with this

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They aren't the be-all-end-all. If your trans is compromised/has some clutch damage it won't help as much as you hope and are just a bandaid. You're better off (in my opinion) saving for a built trans or a kit in a box to build it yourself.

 

[Jncrawford18]

I really hope my trans isn't compromised I just put the tuner and exhaust and down pipe on in the last two weeks and I don't drive the snot out of it I use it to tow and piss off some people from time to time but trans issues are my luck I had a f250 before this truck that I had to build the trans in every Ford I owned the trans went out in lol every gm has lasted so this would be the first one for me if it needs it

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[Jncrawford18]

But also I'm not sure where this is coming from when I'm pulling a real heavy load any time I pull off from a light I get this bad vibration through the truck I've read that it could be from the two piece drive shaft or even getting bad axle wrap that these long bed crew cab trucks are notorious for it but light loads it does fine

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[Mike L.]

Driveshaft center support. Common problem.