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Discussion Starter #1
Good afternoon nation members, I have an issue I would like some input on.
I have an '05 with the lovely 4L60E 4x4 transmission. Recently, I had noticed a rougher than normal 1-2 shift when taking off under light acceleration, however when I took off with a more generous application of the skinny pedal, the shift issue went away. Being an automotive technician, I combed through multitude of TSB and possible fixes along with performing my own diagnostic with what I had available. Long story short, I went ahead and replaced the Transmission filter, removed the old 1-2 accumulator piston and pin and installed the Sonnax pinless kit, then proceeded to flush the entire system. The day I did it, the truck shifted like brand new. There was no more rough transition between the shifts. However, after sitting overnight the problem has reappeared. Just thought I'd pick the brains of some of y'all whilst I had the opportunity. :drinking28:
 

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maniac mechanic
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If you're positive your install of the accumulator was fool proof and the fluid didn't look awful then I would say it's probably in the programming. It drops pressures like crazy on the 1-2 shift so it's not harsh but in turn makes it slip. The update may help but I suggest getting a tune from someone.
 

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Common problem with these trucks. It's a tuning thing. There is a TSB on it. If you take it to the dealership they can do a PCM update and it should be good!
 

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Discussion Starter #9
Awesome! I had an idea it may have been a software issue, but I was not positive. I've got a tuned ECU on the books at Black Bear Perfomance, do you think that's something that would be able to be fixed when I order it?
 
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