5l40e

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.
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

i will test this in the next few days.

do you know if the auto trans is supposed to take longer to shift with higher load going to the trans ? cause mine takes a while to actually complete the shift, any idea ? perhaps i need to experiment with timing retard during shift, unfortunately i never got to test that before they rolled 1.0 ms3 out.
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

Lance wrote:Actually, after thinking about this for a little, I think the table works a bit differently.

In your example, the 3-4 shift will be at 50 mph, AND the 4-3 downshift will also be at 50 mph. What the code does is look for the current bin using the current speed (and load, of course), and the 40 mph (or kph) column represents speeds from 40 to 49.9 (i.e, the next highest value that isn't covered in the next column), and the 50 is from 50 to 54.9, etc. So when you drop below 50.0 mph, you drop to the 40 column, and the target gear becomes 3.

When you are shifting to neutral, are you doing this with the shift lever (i.e. the "inputs") or are you trying using the paddle shifts? It won't shift from the forward gears using the paddle shift buttons. But it should do this using the shift lever. However, the code doesn't distinguish between Park and neutral, so that might be causing some issues in your case (and this can be fixed, of course).
coming back to this, because it's making my brain explode:

so the table would be better viewed like this:
Image
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

also, does does the TCC unlock during shifts ?

i'm seeing various docs saying it's sometimes safe to leave TCC locked during upshift under light loads. but it should be unlocked during a downshift.
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 5l40e

Post by Bernard Fife »

gurov,

The code unlocks the TCC on downshifts, UNLESS the jake brake function is active, OR the full-time lock up is enabled and active (engine rpm greater than stall speed and gear above a user setting).

It's not unsafe to keep the TCC locked on downshifts, but it can cause harsher downshifts if the engine rpm is low.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

configuring pickup of VSS over can for MS3:

Image

Image

i'm not sure where that 45% scaler value is coming from. i had to set that in order to get close MPH in megashift vs MS3.

outputchannels section just has 0.100 for the speedo scaler.

ideas ? (and i will post this on ms3 forum as well)
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

i'm back to driving the BMW, after letting it sit for some period of time due to being lazy to fix the brakes. Now that they are fixed, i'm going to get back into upgrading the gpio box with new code.

just wondering if you ever had any more ideas on how to fix the bugs i was experiencing ?
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 5l40e

Post by Bernard Fife »

gurov,

What bugs were you experiencing? As far as I can tell, the code works as expected.

The latest release code is here: http://www.msgpio.com/manuals/mshift/V2code.html

The latest beta code is here: http://www.msgpio.com/manuals/mshift/V4code.html The beta code has everything the release code has, plus you can set the TCC lock/unlock on all up/downshifts and you can set the maximum line pressure for each up/downshift.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

Re: 5l40e

Post by gurov »

Lance wrote:gurov,

What bugs were you experiencing? As far as I can tell, the code works as expected.

The latest release code is here: http://www.msgpio.com/manuals/mshift/V2code.html

The latest beta code is here: http://www.msgpio.com/manuals/mshift/V4code.html The beta code has everything the release code has, plus you can set the TCC lock/unlock on all up/downshifts and you can set the maximum line pressure for each up/downshift.

Lance.
i was having issues with the shifter not picking up the position after putting it into drive. not sure if you remember the back and forth on that. i will try out new beta code next time i drive.
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 5l40e

Post by Bernard Fife »

gurov,

Yeah, I see the thread from back in April. I believe the issue was that you had set the start up mode to manual, and then the trans had no idea what to do coming out of PNR. As we discussed then, the solution is to not use manual as the startup mode. Newer codes won't let you set the startup mode to manual, in any case. So try the latest code, it should fix things. If not, post an msq and datalog and we'll have another look.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
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