Tranny slip?

[jodell2069]

I have a 2012 lml Denali duramax. I have an afe intake, full turbo back afe exhaust, and I run the hot 150hp h&s tune. From a dead stop or low mph if I stomp it, when it gets around 55 mph usually it acts like it don't want to shift. It don't really seem to have anything working hard or whatever. I'm just wondering if that would be my tranny slipping. I don't think an Allison should slip with such little done to the tuck. It don't have a problem if my torque converter is locked though. I'm pretty new to diesels so I'm just trying to figure out what I got going on. If it is what could I do to help it out?

 

[Harbin_22]

Big tires and 150hp can hurt any stock allison. It might be a fuel pressure problem too. Is it hanging the shift, like just setting at a certain rpm til you back out of it, or is revving up and not going anywhere?

 

[dracing70]

Big tires and 150hp can hurt any stock allison. It might be a fuel pressure problem too. Is it hanging the shift, like just setting at a certain rpm til you back out of it, or is revving up and not going anywhere?

Agreed u can easily hurt a stocker with 150 and tires. Sometimes it's a crap shoot with what a stock ally will handle. If u want to prolong with out going all out try out the pump pressure kits.

 

[jodell2069]

The truck has stock tires for right now. And it's just like hangin there waitin to shift. I'll let off. It shifts. then ill get back on it with no problem.

 

[jodell2069]

Idk if this will mean anything to ya. But me and some friends went to a drag strip one time and i went down the track twice. The first time it done it around 60mph. But I didn't boost the turbo up much or anything on takeoff. The second time I boosted it pretty good and it ran like a scalded dog. So we went back home and to test it I done the same thing. Low boost before takeoff led to the hang up. A high boost let it run like hell.

 

[Harbin_22]

Have you changed your fuel filter while this problem has been going on? Have you tried lowering the tune down some and see if it still does it

 

[jodell2069]

I haven't done either. It's just a once in a while thing. I can't figure it out.

 

[jodell2069]

I'll take it this week and change the fuel filter to see if it helps any. Ever since I put the programmer on its been flashing to change the filter. I just figured it was throwing a code from the programmer but it may just actually need to be changed.

 

[LWATSON]

You could be draining the fuel rail, you could try droping to a lower power level and you may have more power if your draning the rail in the higher setting.

 

[Harbin_22]

Does it set the change filter message when you are WOT? If so, either filter is dirty or you are draining the fuel rail pressure too much. If the filter doesn't fix it, might need a lift pump

 

[jodell2069]

Ok. What would I look for in a lift pump cause I don't know the first thing about one of them lol

 

[LWATSON]

Although Harbin is correct, you may need a lift pump. Installing a lift pump will put you one step closer to hurting your transmission. I personally would drop the power level a little to control the rail draining issue if thats what the problem is.

 

[jodell2069]

Ok. I'll try lowering the power level a notch and gettin a new fuel filter and see what all it does. Thanks a lot for the help fellas.

 

[Harbin_22]

You could be draining the fuel rail, you could try droping to a lower power level and you may have more power if your draning the rail in the higher setting.

100% agree. Should have added that.

 

[Stevenmc89]

Lower power level to 90-120hp, change fuel filter, and invest in a transgo jr ASAP to help keep from burning up that costly allison with the way you're driving it :thumb:

 

[greif03lb7]

Go until she blows tranny kits will be out soon for the lml's:coal:

 

[Mike L.]

You could be draining the fuel rail, you could try droping to a lower power level and you may have more power if your draning the rail in the higher setting.

Ding Ding.

 

[LWATSON]

I know about this, I've drained a few rails in my day

 

[diesel53]

Lower power level to 90-120hp, change fuel filter, and invest in a transgo jr ASAP to help keep from burning up that costly allison with the way you're driving it :thumb:

No trans go jr for that 6 speed. Mike l carries the only mods I've heard of for an lml

 

[Stevenmc89]

Wow I thought all 6 speeds were the same like the 5 speeds in the LB7 and LLY take the same trans go. Well in that case I would rather have the Mike L mods anyway. I mean he is like the man, the myth, the legend so I don't know why anyone wouldn't want his kit