4L80E code

[Bernard Fife]

Guillaume,

Your shift table is all 4's. You also have 'enforce RPM checks' enabled. The result is that any shift from first (necessarily to 4th) would underrev the engine, so no shifting is done according to the table. The actual shifting is being done only because of the under/over rev settings when the engine rpm climbs to the upper limit.

Obviously the gear isn't being updated on the 'rpm check' shifts, and I will fix that for 2.107 (soon).

However, you really should put in a sensible shift table too, it will make the control logic useful again.

Lance.

[Bernard Fife]

Guillaume,

I have put 2.107 code here: http://www.msgpio.com/manuals/mshift/V2code.html

This fixes the issue you mentioned, at least on my bench. However, with your currernt MSQ, it will mean that the trans will go immediately to 4th in auto mode, so you might want to fix up the shift table a bit.

Lance.

[gui67]

Guillaume,

Your shift table is all 4's. You also have 'enforce RPM checks' enabled. The result is that any shift from first (necessarily to 4th) would underrev the engine, so no shifting is done according to the table. The actual shifting is being done only because of the under/over rev settings when the engine rpm climbs to the upper limit.

Obviously the gear isn't being updated on the 'rpm check' shifts, and I will fix that for 2.107 (soon).

However, you really should put in a sensible shift table too, it will make the control logic useful again.

Lance.

Hello Lance,
I saw that I put the table with 4th gear everywhere: I did that when testing the transmission with the wheels raised of the ground to see if al gears would pass. Then I put a normal table. unfortunately I sztill had that old table in the computer, but I did not drive with it.

I quickly checked the code last friday because I have a mecanical/hydraulic problem on the transmission: no cfluid flow to the cooler.
So I put the latest code, a 10kOhm resistor on the speedo output, but the speed on the speedometer os still not right. the needle stays on 100-110km/h at any speed. I will try to measure the signal at the gpio output. Do you know how I could generate a square wave signal to send to the seedo in order to see its value depending on the frequency?

[gui67]

do you think it would le possible to wire the VSS directly to the speedo and then wire the speedo output to the GPIO input?
here is the manual:
http://www.egauges.com/pdf/AutoMeter/479a.pdf
do you think the output signal of the speedometer would be OK?

[Bernard Fife]

gui67,

Yes, that should work. It certainly won't do any harm to the GPIO to try it.

Lance.

[gui67]

Lance, I did not have time yet to try this solution as the transmission has been disasembled again due to an internal problem.
I will try it, but I don't like the solution on a long term:
If the speedometer fails, I won't have any control on transmission, and that is not what I want.

Could this board from Jean help: http://www.msgpio.com/dual_VR/v2_0.html
Would the signal be better for the megashift board? I could wire the output speed sensor to both inputs and then one output on the speedo and the second on the megashift board.
Is the dual VR board less sensitive to noise?

[Bernard Fife]

gui67,

Some users have apparently tried that board with success. However it is not supported here, and I couldn't guarantee anything.

I am currently designing a small add-on board that uses the MAX9926 for dual VR input that also has a constant current driver on it for the high side of the pressure control solenoid (so that battery voltage variations will be automatically taken care of). This will be supported and documented here. (The constant current driver will also be useful for things like PWM idle valves or other solenoids that need a high level of control under varying voltage).

However this board won't be out in the next month unless a miracle happens.

Lance.

[gui67]

Hello Lance,
A quick update of my car:
It seems to work now. I made some corrections on the board: the value of some resistors were not correct on the 4l80e build guide compared to the 4L60e VSS.
Now the speed sensor seems much better.
And for the speedometer output, it also seems to work. I tried it with the wheels of the ground, up to approximately 50km/h. I will try it on the road in the next days but I have good hope it will be OK.
Guillaume

[Bernard Fife]

Guillaume,

Great, I am glad you are making progress!

Lance.

[gui67]

Hello Lance,
I made 100km with the car today.
The 7-segment gear and TCC indicator is working very well. It showed me that my TCC output was always on. That made the car stall sometimes and also very harsh gear changes: the diode of the TCC circuit(PWM2) was burnt, the solder was like rusty on this component... I changed it and the problem was solved (What could make it burn?)

I saw while driving, that some times, the gear goes to 1, then up in 2, 3 and 4 very quickly. After looking at the log, I see spikes in the speed going to 0. It happend maybe 10 times during the drive. otherwise, the speed signal seems very stable.
Do you know what could cause these sigal spikes to 0?