4L60/65 Tap Shift may be possible

[Torqueup]

yeah to get it to upshift, u need to zero out all the down shift speeds otherwise it goes into 1st gear or into a weird neutral state while driving.

has me stumped why it wont downshift because you can do it while stationary. but not once u start driving.

 

[OldSkoolGP]

I believe this is just a misconception.

There is nothing in the tcm code that requires the engine to be running a 58x reluctor. Since everything they get is transmitted over the canbus they just need at a minimum to receive RPM, Pedal Position & engine torgue figure.

All of which the E40 transmit. Remember they are sending the exact same info to the T42 controller for the 4 speed for it shift.

There are a couple reasons why I don't think an E40 will work.

1) The first year of the C6 Corvette in 2005 was sold with the 4L65 automatic and not the 6L80, guess it wasn't ready yet. In that first year, they used the E40 ECM. In 2006 they switched to the E38 and started using the 6L80. I can't see why Chevy would absorb the cost of redesigning wiring harnesses and switching ECMs if they didn't have to.

2) 2005 Pontiac GTOs were the first ones to use the E40 ECM. In 2006, there was a hardware revision to the E40 and a new OS from the 2005 version. We know in the US that you can't use a 2006 ECM in a 2005 GTO, and vice versa, because they switched pin assignments around. If they did a hardware and software update you would think they would include the ability to talk to a 6L80 and therefore Chevy would have kept using it.

So maybe it can be made to work, but for whatever reason, GM didn't think it was worth doing.

 

[Torqueup]

So it may not have been intended to be factory fitted/sold, but apparently it's been done already.

Only thing im guessing there maybe trouble with will be the engine torque, so if you have a boosted motor that exceeds the injector limits you could potentially be under reporting the torque figures.

 

[OldSkoolGP]

So it may not have been intended to be factory fitted/sold, but apparently it's been done already.

Only thing im guessing there maybe trouble with will be the engine torque, so if you have a boosted motor that exceeds the injector limits you could potentially be under reporting the torque figures.

One thing I would be curious to see how someone got around, because I think this may be the reason GM did not go with the E40: The 6L80 does not have a vehicle speed sensor. It uses transmission output speed (TOS) on the CAN, or a replicated transmission output signal (RepTOS) on an output pin from the TCM. Far as I know, the E40 can't handle RepTOS.

 

[07GTS]

usually trans shifts have to pass the speed value to be able to do the shift, so a value of 0 in the downshift into 1st wont ever happen until the vehicle is stopped and turned off and restarted again as the speed cant go below 0 to apply the shift when running so it just stays in 2nd

 

[Torqueup]

with tapshift u need to keep the down speed low otherwise it will auto downshift. for example if 4-3 tutd shift table is set to 50kph. if your at 45kph, it will prevent an upshift. once u get above 50kph it will shift in, then if come off the throttle and start coasting it will downshift at 50kph.

for the upshifts u can leave them maxxed out or set them at a speed u do want an auto-upshift to occur.

sadly it looks like the T42 or the factory cal doesn't like user controlled downshifts. if i bump up the downshift tables the trans will downshift at the set speed.

if i get really bored i'll see if there is another bunch of tables getting looked at it.

 

[07GTS]

if its not factory then it may need the enable set for it to enter the proper mode ? like normal u shift the shifter to the side and it enters sport mode, then to enter TUTD u have to apply a manual shift, there is a setting in hpt that will skip past the sport mode and with the side action on the shifter will go straight into TUTD mode, if its in the right mode then it should only shift according to the user input and nothing alse (except maby a rpm limit for downshifts)

 

[Torqueup]

Got around to changing engine mounts, putting exhaust back on etc, so put the car onto the dyno to run through gears under load.