Got a question for you guys.....
I've been running our daily driver '06 LBZ on the Bully Dog Performance (+125hp?) except when pulling our camper or enclosed trailer. I'm finally getting a little more brave when putting my "foot in it" but can't seem to figure out if i'm limping the tranny or if it just de-fuels that much when passing. When i stomp on it to go around somebody, it will take off but seems to completely lose power when shifting into the next gear unless i let off of it a little. Is this the reason that most of you do not prefer the Bully Dog or am i doing some damage? If so, what can i do to prevent it from happening? This is our "goin to church on Sunday" truck that is completely babied... it just would be nice to show it off if the situation arrives. I would like to drag it or pull it at a local track sometime, but not without being able to figure this out. Any help would be greatly appreciated...THANKS!!

Just had a thought..... could it be my fuel filter? The dash gauge reads 40% and i remember a buddy of mine mentioning to me that his '07 shifted funny when it got below 50%. I realize that the gauge may not be accurate, but i have run mine down to 20 - 30% before..... can't remember how many miles / change. I ALWAYS change mine before winter so it's getting to be about that time. Let me know what you think.

Stock Alli can handle about an additional 100 horse. You could be causing damage but it should throw a code or two. More than likely you are de-fueling. Rather than stomp on it, roll on the throttle. It won't defuel as much if you do that.

Stock Alli can handle about an additional 100 horse. You could be causing damage but it should throw a code or two. More than likely you are de-fueling. Rather than stomp on it, roll on the throttle. It won't defuel as much if you do that.

x2 my Stocker won't take an immediate WOT either. Rolling in seems to be better.

Just had a thought..... could it be my fuel filter? Yup. The dash gauge reads 40%...I realize that the gauge may not be accurate... Gauges? We don't need no stinkin' gauges. I always change mine every other oil change, but I use the ol' seat-of-the-pants meter to judge whether it needs a change before then. Hope this helps.

Another thought...Fresh fuel filter + heavy right foot (could) = limped Allison.

Thanks for the input so far. I know this seems to be turning into more of a tranny topic, but if i am actually "limping" the tranny, wouldn't it last more than a few seconds? It seems to downshift fine when passing, but if i keep my foot in it, it seems to stumble or puke out for a few seconds til i let off and let it shift.

I don't think you are limping the tranny. What I meant was that with a new fuel filter allowing full fuel flow, your 125(?) hp tune could wreak havoc on your transmission. A clogged fuel filter could definitely cause enough restriction to lower the output of the engine.

Odds are that with the tune and the age of the fuel filter you are dropping the rail pressure enough to affect performance but not throw the dreaded fuel rail pressure CEL. Kinda suprising that you haven't thrown that code but everyday is an adventure.:D

its called shift defuel... its annoying. ive been working on trying to get the tuning fixed for this.

Im pretty sure its not causing any damage to your tranny. if anything its preventing damage from happening.

I believe that what you are feeling is just de-fueled shifts, like BullyDogJason said. If you have de-fueled shifts then you are much safer on your trans, even at the 150hp level. No matter what, you are probably burning up your clutches a little though, just putting more power into the trans eats it up quicker. You would definitely know if it was limping the tranny though, when mine did it before my trans kit, the power was really strong, until it happened, then it would slip hard core and it was very noticable.

I think that if you just ease into the throttle instead of smashing it, it will keep the EGT's down, help reduce black smoke and make the shifts really nice and easy.

Sounds like you are draining the rail.

I run into this all the time when trying to run the Predator or now the Edge Race on 85HP, if I try to go WOT the rail pressure drops to around 10-12k when it is commanding 25-26k. And then I have to let up a little to have the truck shift so that the fuel rail can recover.

Per the other threads I have read is if the expected torque output/input to the trans is less than the calculated value from the ECM the transmission will refuse to shift. These same threads also say that in most cases you will not get a CEL for this condition because the load on the engine is so low, most dont see the CEL until they hook up a trailer to add more load and go to CEL.

This condition can feel exactly like the trans is slipping and why you think it might be going into limp mode. What is actually happening is the engine is continuing to rev but is so down on fuel to make any good power it feels like you arent going any faster.

I have tried fresh fuel filters with little to no change, where others have had a little more success, but I have read that on potential long term solution is to add a lift pump, which I am currently shopping for so as not to keep replacing filters early.

If that is the case, which it sounds very similar in deed, then a lift pump should help alot. I have never had that issue because I had my pump in very early on so I would not be able to shed light on that like Semi-Crazy.

Semi-Crazy,

I would recommend the Airdog 2 and the bored out Rail valve from PPE. Then you can delete the stock fuel filter and just use the airdog, which makes changing the fuel filter very easy.

Might check for soft fuel lines collapsing from tank to filter on hi fuel demands. CP3 is trying to suck it forward hard. Lift pump is the helper to push it to the CP3. Hi pressure Good Year hose or braided line is a fix for soft rubber.

Might check for soft fuel lines collapsing from tank to filter on hi fuel demands. CP3 is trying to suck it forward hard. Lift pump is the helper to push it to the CP3. Hi pressure Good Year hose or braided line is a fix for soft rubber.


Agreed, good input for anyone and lots of threads on this as well. I plan to check when adding a pump at the end of the month. Might run new hose all the way to the CP3 as well to eliminate the stock filter housing.

What is Limping?