100% line pressure in reverse

[gboezio]

Hi, The truck is a 84 CJ7 Magashift 4L80E /LY6/Dana300 I went for a for a drive this week with the truck, it has a pretty large cam that tends lead to idle ocillation so it idle pretty high around 850, when I engage reverse it will chirp the tires, looking at the logs, I can see that the line pressure is rising to 100%, I have shearched but I can't find a setting to lower the pressure.
Can't post log it's too big


Also, I want to tell others to retain the safety devices of a stock transmission, reverse lock, no start in gear ask my toolbox !
I will use the shifter switch as a no start switch

I have started the truck standing on the ground leaned on the seat, but I previously had to pull the shifter to D1 to open the electronic box, cold idle was set to 1200, BAM !!

[Bernard Fife]

gboezio,

I can put in some options for reverse line pressure - use 100%, use a fixed user-specified value, or use the table. Look for this in the next beta code (out in the next day or two).

Lance.

[Bernard Fife]

gboezio,

I have put 4.117 beta code that allows you to limit the reverse gear pressure on the beta page. Check this post out for more details: viewtopic.php?f=4&t=240&p=3292#p3292. You can find the reverse pressure limiting options under 'General Settings -> Shift Factors' (though they may eventually be moved to their own menu as that one is getting crowded).

In the end, I decided that two pressure limiting options were a good start. Instead of having three options as I mentioned above ( 100%, a fixed user option, and use the table), I soon realized that the first two options were the same, if the fixed setting was 100%. So I made 100% and a fixed setting the default.

You can change the fixed value to whatever you like (between 100 and 40, lower number gives less pressure since this is a bleed valve and the PWM% is 100-setting). If you use the table, the line pressure PWM will be derived from the first few columns of the 16x9 line pressure table, ad thus the pressure will depend on both load and speed (not sure how fast you might go in reverse, but the table will be used in any case). The value in the bottom left corner of the table would be the one most likely to be used when pull the lever into reverse at a stop.

However, if you don't have a lot of vacuum at idle, it may be better to use the fixed setting for reverse, this will be less prone to fluctuation, and it will be easier to set it low enough for smooth engagement without restricting the line pressure in the forward gears.

If there are other reverse pressure limiting options that make sense, please let me know and we will have a look at what it might take to implement them.

Lance.

[gboezio]

Thanks a lot this is great, I will review a few things that I thought that could be corrected, but yesterday I could make the controller go in automatic mode, it works very well, still small glitches, I was trying to figure why manual mode would not allow me past 3k RPM, by stretching the gears on the table I could reach 4200 RPM, will adjust tonight

I will review my install tonight and check if there anything than can be done to make it even better
Enabling metric is changing the unit to °C, but the numbers shown are still in °F.
Also I wanted to know is there was any fail safe regarding the VSS, if the signal is lost, will the controller dump the first gear or the code recognize it's in high gear and that a downshift will destroy the engine and/or cause an accident
I have noticed that whatever the rpm was, upon closing the throttle the RPM will drop to idle, not sure if there if a sprag clutch in this transmission, this removes the risk of accident and increase fuel economy, but not much engine brake (for now, still learning all the settings), I will check this on the web to know the exact construction of the 4L80E


At first I thought that the inputs were to indicate in what gear the trans was in, (to confirm gear position), but I have found out that it was the shifter position D4, D3, D2, D1.
I have made a safety relay to cut injectors on one bank, the low side go to a MS3 output, if TPS>20% and RPM>1500 output=1, the high side goes the the brake circuit, this could be implemented in the MS+GPIO relationship, some of the installs are pretty dangerous, mine is one of them (overpowered chassis)
By the way the VSS circuit hack I have made works wonderfully, stable and no spikes (even with all the noise on the car)

Good work !!

[Bernard Fife]

Also I wanted to know is there was any fail safe regarding the VSS, if the signal is lost, will the controller dump the first gear or the code recognize it's in high gear and that a downshift will destroy the engine and/or cause an accident

gboezio,

As you know, the VSS is the most important input to the controller, and it really needs to be right for the controller to work properly. However, there is an optional (but recommended) safe-guard called RPM Checking. It will prevent downshifts (and force upshifts) if the resulting rpm (based on the change in gearing from the current gear to the target gear) would be above (or below) user specified values, independent of the VSS. If enabled, it works on both manual and automatic modes. In fact, rpm checking could be used to shift the trans all the time, if you always wanted the shifts at the same rpm. You can read about that here: http://www.msgpio.com/manuals/mshift/V41tune.html#gr It may also be why the manual mode won't let you go past 3000 rpm.

Enabling metric is changing the unit to °C, but the numbers shown are still in °F.

Because of the way TunerStudio and the controller interact, you need to do two things to get metric values and units:

1)You need to change the Imperial Metric setting under 'General Settings->Units' (which changes the magnitude of the calculated values returned from the controller), and

2) You also need to change a setting in the 'Project->Project Properties->Settings'. This setting is either 'NOT_METRIC' (prior to the most recent code), or 'IMPERIAL' in the latest code, to be 'activated' to display metric units. There is more about that here: http://www.msgpio.com/manuals/mshift/V41tune.html#gu

Also, there was a problem with the metric conversion in some recent codes, this is fixed with versions 4.115 and higher. For background, see: viewtopic.php?f=4&t=240&p=3292#p3266 For the latest code, see: http://www.msgpio.com/manuals/mshift/V41code.html.

So make sure you have done both of the above steps, and are using a 'fixed' code version. Some other users are having some trouble with this setting, though. It works fine for me, and I am waiting for more information to see what the problem might be,. If you have done all the above steps, and still have issues with the metric/imperial displays, please post a screen shot that illustrates the problem (along with an MSQ), and I will dig into it.

Lance.

[gboezio]

Thanks Lance, this morning I'm running in a major issue, the TCU is locking up upon burning my new tune from MS3 Can bus, I can hear the solenoids filckering, CAN bus down and RS232 down, I can bring it back reflashing the TCU, but as a reflash the whole controller then power cycle, il fails every time.
I'm still trying to find the setting that make this happens but I made a heck of a lot of changes yesterday and my backup is way old
Will write back if I can find it

[Bernard Fife]

gboezio,

This is the only thing that comes to mind without more information:

Note: When in bootloader mode, the GPIO allows a full 12V to flow in the TCC and Output3 (aka. SolC, 3/2sol) circuits. If your set-up depends on PWM to limit the current in these solenoids, you MUST pull the 5 Amp fuse to these solenoids (shown in this wiring diagram) before entering bootloader mode to load new code. The 4L60E does not need to have the fuse pulled in bootloader mode.

It is in step #3 here: http://www.msgpio.com/manuals/mshift/V2code.html or here: http://www.msgpio.com/manuals/mshift/V41code.html

If full current is flowing when PWM is required to limit it, this can cause all sorts of disruptions.

Lance.

[Bernard Fife]

Another thing that I suppose might do this is if the MSQ is corrupted, and it is setting the CAN and/or serial parameters incorrectly.

[gboezio]

Here the long story, I have tried to reflash the TCU again trough the CAN bus, if failed again upon power cycle, but the controller act normally as I put in bootloader and off, then i configure with a temp trans file, then I power cycle no problem, then I use the main tune to reflash (trough can from ms3, power cycle and bam failed 3 times already, the timing is too perfect to be a accidental bootloader (pin to gnd) and I have the wires in my hands right now, but maybe the controller can go in bootloader from CAN ??

Now I have burned the whole tune trough RS232 and it worked I can power cycle at will.
But, at first I had 14 units mismatch error messages (all about units), I have power cycled, shut both TCU and TS, opened back again a single setting was left to burn, TPS or MAP_PC (sorry memory failed to exactly remember), I agreed to burn and now it's fine, some settings I have changed yesterday burned trough CAN makes the controller lockup.
Feel free to ask more info, I will do my best to help you resolve this issue if it ever happen again.

PS Both project proprieties and General/units were metric from the start, non metric disabled on prop and metric chosen in Units
The Trans temp is the only unit that does this all others are fine.

Even if I know very little in coding, I suspect that it has to be reflashed in two steps and the CAN bus tried to fill it all at once, like burn some, power cycle, burn the rest

Major at first, but I call it minor now that I have found a way to brun it in the controller, I have other issues that I'm trying to eliminate myself, if it fails I will start another thread

[gboezio]

Hi Lance , ok same problem this morning, try burning trough CAN, no errors, upon power cycle TCU locked up.

Reflashed 2204 monitor, opened main project, burned trough CAN, power cycled, lockup

Reflashed 2204 monitor, opened temp transmission project, burned current tune trough RS 232 TCU input, 14 errors (see screenshot), power cycled TCU and restarted Tuner studio, one difference left VSS_PC table, I agree to burn it burns and the whole tune is in the controller.

Hope it helps and have a great week end

PS I get none of the 14 errors burning trough the CAN bus, maybe it is why my units are all messed up and the lockup can come from the same problem