4L80E PC always 100 percent

[marcars]

Hi,

I've built and installed MShift on a 4L80E and after a few hiccups everything's working. Using an MS-2 for now but will be switching to non-Can when everything's sorted out. Already using ISS as tach input. Just 2 issues that need sorting out:

1. VSS drops to zero every now and then, always at around 90 Km/h. No matter what mask or filter adjustments I make problem stays the same. I'll run new wiring and try a new sensor....

2. This one really breaks me up. No matter what I try, PC is always 100 percent. I've adjusted PC at idle from 90 to 80 percent to see if anything would wake up, the map looks good (default). Because I'm not sure whether I have an early or late box I've tried both PWM settings, no avail. I shoud note that the diode was hooked up wrong at first - corrected that - still no go. But I figure that this is a software/settings issue and not hardware because the TS gauge is showing 100 percent.

I'm fairly sure it's a configuration issue but somehow I can't find it. Could the diode issue at start-up cause something like this?

Any input on this is more than welcome.

Thanks so far,

Marc

[Bernard Fife]

Marc,

Is the engine running? If it isn't running (defined as rpm > 300 in the code), the line pressure PWM% always goes to 100% (which is actually 0% at the PC solenoid, as noted in the manual, since the reported value is 100- the actual PWM%) to save the current load and quiet the solenoid when the engine isn't running. If this is while running, I am not sure if you can use the non-CAN tach with a CAN connection (it certainly wasn't intended to work that way - if a CAN connection is available the intent is to always use the CAN for engine rpm). The line pressure is always 100% in reverse (and a fixed user specified value in neutral, and this could be 100%). The battery voltage adjustment to the PC, as well as the temperature adjustment to the PC could also cause this. But so could bugs in the code! In any case, if you could post and MSQ and the datalog (from the serial port of the GPIO, not a composite log that includes the engine controller parameters) that would help a lot to sort this out.

I'm not sure what is going on with the VSS, Have you tried no masking at all (set the VSS input masking to zero)? You might also try increasing the VSS Smoothing Factor as a work-around for now: http://www.msgpio.com/manuals/mshift/V4tune.html#gv I will see if I can duplicate this on my bench when I have your MSQ.

Lance.

[marcars]

Hi Lance,

Thanks for your reply. I hadn't thought of the RPM input issue yet. This could very well be it. The MS currently just suplies the load (MAP) and CAN communications. I had tried to hook up RPM's but didn't work and I figured that as long as there is an input speed sensor this would not be necessary. Hmm, guessed wrong I guess.
How would this work in a stand alone set-up then (non-CAN)?

As for the VSS, I read that setting the mask to 0 was only possible from code version 2.122 onwards, I'm running 2.111. Would this still work?

Thanks so far,

Marc

[Bernard Fife]

Marc,

Yeah, the tach always gets me on the bench with the line pressure - if I don't have rpm (even with CAN) the line pressure stays at 100%. In standalone mode mode, when CAN is disabled, so is the rpm check for the line pressure. It's does this way because the engine's controller is much more likely to be correct for the rpm, since the engine probably wouldn't run otherwise!

I meant to mention that if you haven't tried 2.128 code (http://www.msgpio.com/manuals/mshift/V4code.html), that is what you should do now. It has a number of fixes to the speedo and line pressure, so it may well fix any issues you see. If it doesn't, then we can look deeper.

Lance.