4L80E Line pressures

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
Post Reply
flak monkey
Posts: 50
Joined: Sun Sep 21, 2014 11:28 am

4L80E Line pressures

Post by flak monkey » Sat Jun 18, 2016 12:28 pm

Anyone got any input on 4L80E line pressures? Infact anyone know what the rise rate should be with throttle position?

I know the standard controller uses TPS for load, and my installation does too (the axis label is wrong). So I'm just interested to know what the standard rise rate is, is it linear with throttle position, or is 100% line pressure achieved at say 50% throttle and it's linear to there. Or does it rise exponentially with throttle position?

I set my lowest row based on the standard line pressure with a closed throttle. So I have about 75psi at 50% duty and 180psi at 100% duty (at idle speed)
(61.9 KiB) Downloaded 389 times
line pressure.JPG
line pressure.JPG (86.57 KiB) Viewed 6250 times

Matt Cramer
Posts: 55
Joined: Thu Apr 17, 2008 5:19 am

Re: 4L80E Line pressures

Post by Matt Cramer » Fri Jun 24, 2016 7:17 am

I would just start with full line pressure across the board, and back it off until the shifts each your desired level of softness.

Posts: 16
Joined: Tue Mar 15, 2011 8:37 am

Re: 4L80E Line pressures

Post by rxl158 » Tue Aug 09, 2016 5:33 pm

Mine is set very similar and has been successfully driving well for the past two years. I even did some doodling with pressure values in the low speed and load region to make it feel like a stock cushy box ;) I've ran it on slicks a few weekends a year and works really well. The "load" should be a function of TPS And RPM if you're using the default table in TunerStudio.
DIY'er with Your help :-)

Posts: 47
Joined: Fri Aug 15, 2014 7:58 pm

Re: 4L80E Line pressures

Post by Rukavina » Tue Aug 09, 2016 9:41 pm

4l80e specs.pdf
(825.02 KiB) Downloaded 315 times
Hope this helps

Post Reply