De-fueling at shift

[tblu92]

Recently I have had a few trucks 2 LLY's and 1 LBZ where I have loaded a mild tow/mileage tune (about 70 HP) and in either the 2-3 or 3-4 shift it won't shift and just hangs at WOT and stops around 3400 RPM's-- If I lift a little off the throttle it will shift--The WOT shift RPM is set to stock at 3200--Some have bigger tires and I made a speedo correction but other than that the trans is stock with the exception of raising the torque limits--I was told I need to de-fuel it near the shift point---is this correct ? And how do i do that? OR how do i make it shift at WOT ? THKS

[The Neens]

Recently I have had a few trucks 2 LLY's and 1 LBZ where I have loaded a mild tow/mileage tune (about 70 HP) and in either the 2-3 or 3-4 shift it won't shift and just hangs at WOT and stops around 3400 RPM's-- If I lift a little off the throttle it will shift--The WOT shift RPM is set to stock at 3200--Some have bigger tires and I made a speedo correction but other than that the trans is stock with the exception of raising the torque limits--I was told I need to de-fuel it near the shift point---is this correct ? And how do i do that? OR how do i make it shift at WOT ? THKS

How many miles on the fuel filters?...

[Sparky8370]

How many miles on the fuel filters?...

I was going to ask the same. That's one of the big signs on my truck that the filter is junk. It hangs on to the shifts way too long. I got a bad batch of fuel that ruined probably 4 or 5 filters in around 3000 miles.

[tblu92]

Are dirty filters usually the cause ? I have used these tunes many times before and never had a problem--I will ask them to change the filters anyway----Could it be anything else ?????

In all these cases they won't shift at all unless you lift off the throttle in those higher gears--

[The Neens]

Are dirty filters usually the cause ? I have used these tunes many times before and never had a problem--I will ask them to change the filters anyway----Could it be anything else ?????

In all these cases they won't shift at all unless you lift off the throttle in those higher gears--

They are often the cause...Good transmission shifts are dependent on how the engine is running...

[tblu92]

My customer is coming over today--I'll recc. changing his filters and will let you know the results--

[tblu92]

UPDATE

Had all 3 customers change their fuel filters---1 guy had just chaged them about 1000 miles ago with cheap Kragens--I had all of them buy the Wix fuel filters-- HAPPY to report that all 3 trucks now shift perfectly !!!
Learned something about cheap filters---especially a trk with a tune---spend the extra $$ and buy good ones-- Thanks all responders for your help
EFILIVE is # 1