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4l80e shifts to 2nd when in first... need help!

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Old Feb 8, 2015 | 08:00 PM
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Default 4l80e shifts to 2nd when in first... need help!

after several attempts at making passes at the track with no luck, im having issues with my 80e that i cant figure out. I can launch the truck on boost, no boost, in first gear or in drive and it will launch hard and then go numb as if its trying to switch gears into 2nd and then back to first and then hauls ***. Does this in drive or pulled in first gear either way. Try doing burnouts in first and it automatically jumps in 2nd gear....what the heck is going on with this trans? Its behind my 4.8 with turbo. My tuner has submitted a couple different 4l80e tunes and segment swap to no fix....
Thanks for any tips or idea's on this,
Jamie
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Old Feb 8, 2015 | 08:47 PM
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What year is the truck?
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Old Feb 8, 2015 | 09:03 PM
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Originally Posted by 03sierraslt
What year is the truck?
Its my 90 454ss truck. I have the PSI wire harness for LS/4l80e combo. We tune it with hp tuners and have done the segment swap aswell. Drives normal and works great except when you launch it in drive or 1st either one...tries to shift to 2nd and then back and forth a few times and then just takes off in 1st hauling ***. Im at a loss here.... torque management is turned off aswell.
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Old Feb 9, 2015 | 06:48 AM
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What kind of oil pan do you have and what 60 fts. are you pullin off? If its hitting super hard off the line maybe the fluid is building up at the back of the pan and running the filter/pickup dry?
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Old Feb 9, 2015 | 07:45 AM
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Originally Posted by livefast1
What kind of oil pan do you have and what 60 fts. are you pullin off? If its hitting super hard off the line maybe the fluid is building up at the back of the pan and running the filter/pickup dry?
I've seen this happen, it can be verified with a pressure gauge.
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Old Feb 9, 2015 | 08:44 AM
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its the stock 80e pan and i have a yank power adder 3400 converter. i changed to this converter from my old revmax and it definitely tries to 60' better now but this happens on every launch within a truck length off the line on both converters.

it starts to launch very good especially when i leave in boost but then the 60' is dead when it pulls this mess im talking about. best 60' has been a 2.05 because of this crap but will then still run 92-93mph and only 8.30's because it wont launch and stay locked in first gear. im getn frustrated trying to figure this out!!
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Old Feb 9, 2015 | 08:52 AM
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Run a pressure gauge and see what it does, if it's pulling air you will see it.
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Old Feb 9, 2015 | 09:11 AM
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Originally Posted by 03sierraslt
Run a pressure gauge and see what it does, if it's pulling air you will see it.
i will give that a shot and see what i get

thanks
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Old Feb 9, 2015 | 01:43 PM
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If you find this is the case id pull the trans and check the clutches. If you've launched like this a few times I would bet you hazed the clutches when the pump was sucking the filter dry.
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Old Feb 10, 2015 | 08:40 AM
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i unplugged the 3 harness plugs from the trans and plugged my Jakes Performance manual control box back on it that i first ran with the trans on the old big block and problem solved. took it for a drive and it will hold first solid now and no more jumping between 1st and 2nd on a launch. its undoubtly something in the tune with torque management or something that isnt working right.
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