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normal or not?

deezl duly

deezl duly

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riverside ca.
as stated before, just got my dually runnin,and so far, runnin great. just wondering about the 4l80 traits. when im cruising along and let off the throttle, the rpms go to idle. even if im in 3rd the same thing happens. is this normal?any other automatic i ever had,(especially in the lower gears)would slow down, almost like a stick, gradually. just wondering.thanks for your help.:???:
 
Every Automatic I've ever had has Driven just like how yours is Now. When I've let Off the Gas, its' Stayed In Gear for maybe a Second or 2, then Dropped to Idle and I just Coasted.
 
Sounds normal to me. The 4L80E prior to 99.5 had a hollow input shaft that was prone to snapping from a rapid change in thrust. So GM made it so the torque converter immediately unlocks when you let off teh throttle or touch the breaks. It's a safety measure programmed into the PCM.
 
thanks for the info i kinda thought it may be normal, after reading about the 4l80e it just seems more noticeable.this is one temperamental trans. it seems that when i drive home from work in the early hours it wont go into overdrive and the cruise wont come on. i read that if its not up to normal temp, that it happens that way. i live in so. cal so it never gets too cold.the trans has 74.000 miles and a fresh fluid/filter change. any ideas? im gonna put a heath chip soon so maybe that will help. thanks in advance for your help.
 
What year truck? The PCM will lock out OD when the engine is cold, but i believe at 140 or so it gos into normal mode. If the coolant temp sensor is reading off it can also cause it not to go into OD soon enough.
 
If you shift to manual 3rd does it hold up the engine RPM? 2nd? The transmission has overrun clutches that come on when manual 3rd is selected. Otherwise they can freewheel and let the engine idle. Mine does not freewheel except it will in manual 2nd because something is busted.
 
when i put the motor in i did as you guys recommended and made all new grounds and even added extra grounds so i think im covered there. guess il keep a closer eye on it and monitor it better. just hate goin 60 mph@2700 rpm lol. keep ya posted thanks
 
What year truck? The PCM will lock out OD when the engine is cold, but i believe at 140 or so it gos into normal mode. If the coolant temp sensor is reading off it can also cause it not to go into OD soon enough
Click to expand...

Ferm is right , it won't go in to OD until predermined temp is reached.

Also unlocking when letting up on throttle might also be for MPG as to slow down less and maintain speed longer especially when going down hill.
 
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