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This is a new build that I just got running. It shifts just fine part throttle but will not shift under full throttle. Part throttle goes up and down through the gears with no issues, including OD and TCC lock and unlock.
Full throttle the computer is commanding the shift but the trans does not come out of 1st and it hits the rev limiter. Once I back off it will go ahead and shift.
The details of the build are.
55 Chevy 210
6.0 LQ9
2004 4L80E
Holley Dominator ECU
Borg S480 turbo
3.55 gears in the 9"
28" tall Hoosier quick time pro tires
In the data log you can see the shift command (shift point set at 6400) but the RPM never drops and it quickly hits the rev limiter at 7K. Speed when it hits the limiter is 59 MPH so with my gearing that's telling me it is not getting out of 1st gear even though the log shows the trans should be in 2nd.
Can you get a breakout box.... Or a scanner that can watch the commands and actual shifts at the same time? We have to see if what is called for is really shifting the solenoids, the shift valves and fluid flow.... Also look at the ratio screen.... Which should show a change in the ratios when shifting.... This is just testing.... If someone installed a shift kit or modified the trans.... We would have to chase down any mistakes installing shift valves and springs... Etc...
I don't have access to a scanner or breakout box. I can see what the ECU is commanding from the data log but that's it. I did order a pressure transducer so I can see what the line pressure is actually doing. The tune drops the duty cycle on line pressure to 0 once it hits positive boost so that should max it out.
My plan is to lower WOT shift point to see if it makes any difference. I figure there's not a lot of time between my 6400 shift point and the 7000 limit (looks like less than 1/2 a second according to the log), it's accelerating pretty dang quick at that point.
I'm also trying to find out what if any mods were made to the trans.
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4L80 shift issue 
