Help with 4L80E

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.
flak monkey
Posts: 50
Joined: Sun Sep 21, 2014 11:28 am

Re: Help with 4L80E

Post by flak monkey »

I think I have figured this out, well half of it....

It was shifting late because it was still using map as load even though I had changed the project properties to TPS.

I've reloaded code again, created another new MSQ and it seems to be shifting as per the map now.

Only thing is I still don't have 1st gear except in manual 1 lever position.

My line pressures are:
120psi in park and neutral
280psi in reverse
175psi in all other lever positions (d-1)
flak monkey
Posts: 50
Joined: Sun Sep 21, 2014 11:28 am

Re: Help with 4L80E

Post by flak monkey »

Log attached, shifting much better, but still missing first gear...
Attachments
2016-04-24_10.30.40.msq
(61.89 KiB) Downloaded 553 times
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: Help with 4L80E

Post by gui67 »

HEllo,
it is the msq, not the log.
for your load problem, check what the MAP vs TPS for load (MAP%) in the Throttle and Load Factors menu.
I put it on 100% MAP now, but before I did not understand why I could see a small load with 200kPa MAP... it was blended with TPS.
Maybe you have to adjust it to 0% MAP (100% TPS) if you want it like that. you have 25% for the moment in the attached msq.
flak monkey
Posts: 50
Joined: Sun Sep 21, 2014 11:28 am

Re: Help with 4L80E

Post by flak monkey »

Oops. Here's the log.

I'll see how the load goes with it on KPa.
Attachments
2016-04-24_10.29.28.msl
(216.09 KiB) Downloaded 492 times
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: Help with 4L80E

Post by gui67 »

The controller seems to select the right outputs for the 1-2 shifts. but the transmission does not follow.
I would try to manually ground the output 1 going to solenoid A to check if it changes something. or check with a multimeter if the output is grounded at this moment.
Did you check the shifter setting? maybe it is not set properly and the manual valve is not on the right position with the shifter in D.
flak monkey
Posts: 50
Joined: Sun Sep 21, 2014 11:28 am

Re: Help with 4L80E

Post by flak monkey »

Driven the car on the road today and 1st gear is working fine now - expect it was something mechanical - could have been as simple as one of the checkballs was still stuck in the vaseline or something. I don't know but it's working now...

However I have some tuning issues now that I need some help with :) I'll start a new thread
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: Help with 4L80E

Post by gui67 »

The tests before were done with the wheels of the ground?
If yes, it was maybe friction between the discs or the band that made the wheel turn like in second gear: not enough torque to keep the wheel from turning.
If you try again with the wheels up, I think you will see the same behaviour as before.
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