Kick down tuning

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.
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warrjon
Posts: 6
Joined: Wed Dec 17, 2014 10:07 pm

Kick down tuning

Post by warrjon » Tue Jul 25, 2017 9:25 pm

Background

I have a 4L60e 1994 vintage behind a Jaguar V12 that redlines at 6500rpm, I have 1-2 upshift set at around 6000rpm at 100% load which is about 65km/h

The issue is the Mshift kicks the trans down to 1st at 60km/h for a milli second then immediately upshifts. I have searched for a tuning parameter to prevent this but have come up empty. Has anyone got any ideas how to fix this.

Thanks Warren

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

Re: Kick down tuning

Post by Rukavina » Tue Jul 25, 2017 10:57 pm

Try increasing shift hysteresis so it has to see a bigger change before shifting again. It sounds like soon as it shifts down it puts engine in a state where tranny wants to shift back up. I read these posts every night on my phone to put me to sleep so I am not at laptop to look at settings. Post your msq and will try to look at it tomorrow at work

warrjon
Posts: 6
Joined: Wed Dec 17, 2014 10:07 pm

Re: Kick down tuning

Post by warrjon » Tue Jul 25, 2017 11:49 pm

Sorry I didn't explain myself well...

The trans is not upshifting then downshifting.

If I'm driving on the open road and go to overtake (like if I'm stuck behind a tractor at 60km/h) when I floor the throttle the trans kicks back to 1st gear then immediately upshifts if I'm above the upshift point then the trans kicks back to 2nd which is ok.

I tried to activate RPM checking but it just keeps greying out and now I have to pull the TCU to re-flash it (it'll take me 1/2 hr as it's under the drivers seat).

I'll post the MSQ tomorrow, it's on my other laptop which I don't have here.

thanks
Warren

warrjon
Posts: 6
Joined: Wed Dec 17, 2014 10:07 pm

Re: Kick down tuning

Post by warrjon » Thu Jul 27, 2017 6:20 pm

Here is a copy of mt msq. Code is 5.201

To avoid this I have set 1 -2 upshift low so the trans won't kick down to high in rpm range
Attachments
Mshift-Jag-V1.2.msq
(62.22 KiB) Downloaded 7 times

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

Re: Kick down tuning

Post by Rukavina » Fri Jul 28, 2017 5:55 pm

DO NOT LOAD THIS TUNE! mine is a 4l80e not a 4l60. I looked at your settings and other than kilometers don't work well with my brain (American) some of what stood out to me was some of your tables. your tps by rpm table is different than mine. I have that table bypassed. granted I am not done tuning or even completely finished with install. I still have to finish my iss and a few other details. I have about 4 thousand miles on it but works good and shifts well, up and down. so my vss is configured for a drac speed module so those settings are different. start with making sure however your speed sensor works that it works well, if its glitchy you will never get a handle on it. do the compare tune thing and look at the differences with mine to yours. remember that ALL my settings are in imperial not metric. when I compared yours some of my setting pages showed in metric but the values where American. like the page loaded said temp in Celsius but had my Fahrenheit value in the page. I would compare the differences and read up. you could import my tables and adjust your km values if you wanted. this is just something to look at but like I said mine upshifts and downshifts well. I also noticed your main controller is on b&g code so that might have a slight difference with can comms.....
4l80e with american settings.msq
(62.2 KiB) Downloaded 8 times

warrjon
Posts: 6
Joined: Wed Dec 17, 2014 10:07 pm

Re: Kick down tuning

Post by warrjon » Fri Jul 28, 2017 7:32 pm

Thanks for the reply.

I've compared your tune to mine and adjusted some of my parameters.

My transmission VSS is good as I also use it for my cruise control, and I have monitored it with my scope.

I don't use the Jag VSS for TCU and CC it drives the speedo, ECU and trip computer ATM.

I still have the same issue.

With 1-2 upshift set at 65km/h (5900rpm) if I am driving at 63km/h (5700rpm) and plant my foot the trans shifts to 1st then immediately upshifts to 2nd

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

Re: Kick down tuning

Post by Rukavina » Fri Jul 28, 2017 9:36 pm

I am no expert but grab a datalog...
Also try jumping over to the msextra forum for the microsquirt transmission control section. They might have an idea even though it's not for the gpio board or b&g firmware.

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