quick question

[Bako_Dmax]

Ive read this before but never understood what causes it. How can a dirty fuel filter have an effect on the allison? Im just curious ive read when some people are having trans issues with no codes to change the fuel filter, whats going on?

 

[sweetdiesel]

Ive read that before also,I ASSume that it's not fueling properly and messes with the shifting

 

[Kat]

I know when I have an old filter it shifts for $hit. Normally a really hard down shift. Change filter and it goes away

 

[JMDuramaxLB7]

My truck always seems to shift up through the gears real firm when my filter gets dirty, don't run worth a shit either.

 

[The Neens]

Ive read that before also,I ASSume that it's not fueling properly and messes with the shifting

I ASSume the same thing...

 

[Mike L.]

The Alli is computerized trans that is commanded to shift after certain parameters are met. Speed sensors, throttle position and such. When a fuel filter is restricted the throttle position will be different because it will take more to achieve the same speed and the resulting output speed will not meet the throttle angle according to the existing programming. When this happens the TCM thinks you are in partial detent or quasi passing gear and won't give a shift command till the proper output speed is attained which isn't going to happen with lack of fuel. Plain and simple; TCM just doesn't know what to do with all the wrong signals coming in. Hope this helps.

 

[slowlmm]

intereseting. could the same thing happen when not holding rail presure as well like when raceing or wot . causing slow or bad shifts ?

 

[Mike L.]

intereseting. could the same thing happen when not holding rail presure as well like when raceing or wot . causing slow or bad shifts ?

Yes.
Now go put a lift pump in.

 

[Bako_Dmax]

The Alli is computerized trans that is commanded to shift after certain parameters are met. Speed sensors, throttle position and such. When a fuel filter is restricted the throttle position will be different because it will take more to achieve the same speed and the resulting output speed will not meet the throttle angle according to the existing programming. When this happens the TCM thinks you are in partial detent or quasi passing gear and won't give a shift command till the proper output speed is attained which isn't going to happen with lack of fuel. Plain and simple; TCM just doesn't know what to do with all the wrong signals coming in. Hope this helps.

Good info thanks.

 

[slowlmm]

Yes.
Now go put a lift pump in.

its enroute . looks like you have something to do next week :hug:

 

[Mike L.]

its enroute . looks like you have something to do next week :hug:

"I'm sorry this is the transmission section. Please find the proper place to make your lift pump installation request":rofl:

Bring me the setup when you get it Tommy so I can look at it and see what else I may or may not need. The above was my last snyde remark about the subject.

 

[paint94979]

The above was my last snyde remark about the subject.

Ya right:rofl: Mike you need to stay on his ass about the lift pump