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Allison shift problem

calgator73

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calgator73 Senior Enthusiast

calgator73

Posted
Posted

Yesterday...1/4 tank of fuel transmission hung on 2-3 shift during WOT up an on-ramp. Had to let off to shift.

 

No tune...only "mod" billet bleeder screw. FF only 12k miles 65% life.

 

Thoughts?

 

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Chris2087 Enthusiast

Chris2087

Posted
Posted

I have an idea, perhaps during WOT, the TCM wont allow an upshift until the RPM and torque are within a set range.

calgator73 Senior Enthusiast

calgator73

Posted
  • Author
Posted

I have an idea, perhaps during WOT, the TCM wont allow an upshift until the RPM and torque are within a set range.

That's what i was thinking based on some reading. Looks like clogged fuel filters, vacuum leaks at the filter head and low fuel with some kind of fuel tank mod can cause it. With full tank couldn't duplicate.

 

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Drive it don't beat it and all will be fine

Something's up though

 

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calgator73 Senior Enthusiast

calgator73

Posted
  • Author
Posted

That's what i was thinking based on some reading. Looks like clogged fuel filters, vacuum leaks at the filter head and low fuel with some kind of fuel tank mod can cause it. With full tank couldn't duplicate.

 

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Something's up though

 

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Full tank of diesel had no issues. Less than a quarter tank I have issues.

 

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SMiller Senior Enthusiast

SMiller

Posted
Posted

Drive it don't beat it and all will be fine

Loaded pulling up on ramp...

 

Truck should shift just fine at WOT empty or loaded, sounds like a TCM issue.

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