[Col O/S]

I am rebuilding a 72 Holden Monaro and installing a 350ci Chev with a th700 , 4R700, 4L60 transmission. I have already purchased a V0.4 Speeduino, though at the moment this is in Australia and the vehicle and I are in Thailand. The transmission is basically the last of the non-electronic types, but does have a torque converter control (TCC) electrical control signal. There is a electric pressure switch inside the transmission that detects when in 4th gear, and allows the TCC to operate. This will probably be the first of a series of questions on using additional I/O and I have a feeling the answer will be use a GPIO board.

The logic for the TCC is basically - Footbrake not on + in 4th gear + (RPM > Setpoint A) + (MAP > Setpoint B).

The footbrake sense and 4th gear control logically live outside Speedy. However as the RPM and MAP values are already in Speedy, how is it possible to obtain an output based on for example: RPM > 1800 and MAP > 80 delay for 2 seconds and output = on ?

Cheers

[PSIG]

The logic for the TCC is basically - Footbrake not on + in 4th gear + (RPM > Setpoint A) + (MAP > Setpoint B).

Agreed, the most elegant solution may be GPIO, if the additional if-statements cannot be added to code. Without going that route, you could combine external and internal functions into a workable solution today.

One example could be to use the Speeduino VVT function in MAPxRPM and "switch" mode, allowing any combination of MAP and RPM values for basic switching in the desired range. Coupling that with a solenoid power circuit using a common P_MOSFET and a couple small resistors, activated by the 4th-gear switch grounding the gate, and deactivated when pulled high by the brake light circuit would complete the package.

Function would be Speeduino providing simple TCC solenoid ground when it is in the tuned MAPxRPM range, but the TCC power would not be active unless both the [brakes lights OFF] + [4th-gear switch CLOSED].

The components could be on the Speeduino proto area, or most anywhere else. A similar system using two micro relays rather than the FET is another option. If delayed engagement were desired (most are simultaneous), a simple delay could be added to the MOSFET, or chained to it. Disabling TCC if desired at high loads/rpm would simply be tuned into the VVT table. As I said, the GPIO or code mods would perhaps be more elegant, but there are some rather simple solutions if that helps the creative ideas flow or provide other acceptable or immediate solutions. Hope that helps.

David

[Holden202T]

Years ago i put a T700 behind a straight 6 and had to overcome the TCC .... unfortunately the efi i was running at the time didn't have the ability to control anything more than the engine, but what i came up with was a vacuum switch, which was designed for dis-engaging the A/C clutch on heavy throttle, along with wiring mods inside the box, i made it so that it had to be in 4th and below a certain throttle (vacuum) and it would lock.

The main issue i had was i had to manually drop it back to 3rd when i would slow down but it would still be in 4th.

It certainly wasn't as nice as having it work dependent on road speed but it was better than nothing - maybe something that you can use here to do it and use rpm/map table in place of my pressure switch which once tuned properly should fix the slowing down issue i had.

below is the wiring mods i did inside the gearbox.

t700-wiringmods.jpg (42.87 KiB) Viewed 2853 times