Exhaust brake

[miwyl]

Hi All
I'm getting close to doing my own Mega-shift install and I'd like to get some feed back or reassurance
My application is with a diesel engine so no Mega-squirt or CAN network shifting will be manual with a lever on the center console . I will use a tps for load sensing this particular diesel engine has an exhaust brake which I wouldlike to implement it will be cable activated by a second lever on the console in order to use the exhaust brake with an automatic transmission it has to have the tcc is locked and a high enough line pressure to ensure no slippage of the clutches. locking the tcc on command could be done with a micro switch and resistor in the temp circuit fooling the gpio board that its running hot when the exhaust brake is engaged. For raising line pressure a second switch
activating a variable 5volt voltage source to fool the gpio board that there is a high load (But actually the foot is off the throttle)Does anyone see any problems with this? are there better ways to control the tcc and line pressure?
Thanks in advance for any help.
miwyl

[Bernard Fife]

miwyl,

I think that should work.

Or I could add this as an option to the code. It would use one of the unused inputs as a jake brake input, and force the TCC on and the PC high if that engine brake input is pulled low (with a switch that grounds the input).

You would have to let me know which input might be unused, though. Since this is nn-CAN, we can't use the load input (AD5/EGT1/Amp 24). And it may well be that diesels are often combined with 4WD, making it undesirable to use the 2/4WD input (PE1/GPI1/Amp 5). The line pressure sensor is one that people might not be using (especially after they have got set up, then there's no real need for it most of the time), so that's a possibility.

Let me know what you think would work best, and I'll see what I can do.

Lance.

[miwyl]

Hey Lance
Being an analogue guy it never occurred to me it could be done in the code but it makes perfect sense
since this is all experimental and I do plan to install a pressure sensor for data logging we'll leave the code as it is for now
Using a adjustable voltage reference would allow me to apply just enough line pressure to prevent slipping.
I'm sure I will have more questions
so thanks for all the support
Miwyl

[Bernard Fife]

E4ODnot, miwyl;

Yes, these things are already in the code. There's also a fail safe that unlocks the TCC if the speed falls too low (you certainly don't want it engaged while stopped).

Lance.

[Bernard Fife]

All,

I will put draft 2.002 code in the 'code updates' thread in the next day or two that has the 'engine brake' function in it. This uses the line pressure input for a signal that the jake brake is activated (by grounding Amp pin 27). You set up to use the pin as a engine brake imnput under 'General Settings/Standard Inputs/Outputs Configuration/Line Pressure Input' where you select "Use as Engine Brake Input".

This will cause the line pressure to go to the maximum, and the TCC will be applied. The minimum TCC speed and gear still apply, so you must consider those parameters carefully for this application. The engine brake function is not tested at all yet, though.

Lance.

[miwyl]

Hi Lance
Thanks for going ahead with the code changes I will use an analog mechanical gauge to monitor line pressure
it will save me a hundred dollars over the MSP6907-ND and make the design of brake shifter simpler.

I know that there is built in latency when shifting with buttons that's adjustable
would the tcc lock up "exhaust brake" function have any appreciable latency?

Also in Tuner Studio general settings the non can load calibration is grayed out
does that still have to be developed I'm only using lite version and am off line?
Thanks again for your support
miwyl

[Bernard Fife]

miwyl,

To access the non-CAN Load calibration, you first have to tell the controller you aren't using CAN. You do this under 'Tools/CAN Configuration/CAN usage' and set it to CAN disabled. This should work on all tuning software.

The jake brake input is checked approximately 8 times a second, and is active immediately (within a few milliseconds). It will take a little longer for the hydraulics to catch up, but it wouldn't be too long, I think.

Lance.