Harveys QC

[b3lha]

Originally Posted by svxistentialist

Very interesting Tom. It's starting to make sense.

The percentage torque distribution [between the front and rear axles, ignoring side to side for a moment] is decided by the speeds shown to the TCU by Speed sensor 1 and Speed sensor 2. Differences between these signals will cause the power to be sent from the slipping axle to the one with grip [the slower one]

The conditions you describe are perfect for such a spike. Powering uphill on slippery asphalt weight goes to the back, front end will start to lose traction if enough power applied. In this scenario under steady state strong acceleration in whatever gear [WOT] it will be normal for the computer to sense slippage at the front axle and send as much as possible to the rear. This should be as near as dammit to 50/50.

Now a change of state is applied; downshift at WOT. We are so used to the SVX not breaking traction because the computer works so well at traction distribution that we expect the torque percentage to be always within the envelope. But in this 50/50 state as the downshift happens and the revs go up to a higher power and torque level, both back wheels break traction momentarily when the clutches bite.

The unthinkable happens and the rear axle revolves faster than the front for a moment or two, hence the 51% spike. As it bogs down it reverts back to its natural state in the lower gear.

Well, that's how I see it. Any better ideas?

Joe

The torque distribution may well be decided by comparing the differing speeds of the front and rear wheels. But I find it hard to believe that it is measured by comparing them.

YT, what TCU address is the select monitor querying when measuring the torque split?

Phil.

[TomsSVX]

Originally Posted by b3lha

The torque distribution may well be decided by comparing the differing speeds of the front and rear wheels. But I find it hard to believe that it is measured by comparing them.

YT, what TCU address is the select monitor querying when measuring the torque split?

Phil.

The 4wd duity sol.

I forget the address but I had listed them in the ECU dump thread

Tom

[b3lha]

Originally Posted by TomsSVX

The 4wd duity sol.

I forget the address but I had listed them in the ECU dump thread

Tom

OK. The Sol C duty cycle, that's what I expected. The main subroutine that calculates the duty cycle sets it between 5% (50:50) and 95% (FWD). I expect that the select monitor calculates the torque split on the basis that the duty cycle will alway be in that range.

But there is another subroutine appears to tweak the duty cycle a little based on throttle input. I think it is possible that on a rare occasion, the duty cycle may fall below 5%. This will upset the select monitor's calculation so that it shows 49:51, even though that is not physically possible.

[blueji]

[QUOTE=svxistentialist;580910]

Originally Posted by blueji

John

Phil has reprogrammed my UK TCU so that Power mode can be forced on, and left permanently in the on position.

This can be achieved by a console switch in the JDM cars. It is much more difficult with the UK gearbox because the firmware is different. Phil monitored all the functions and has re programmed it to allow Power mode in the place of the Econ mode that UK gearboxes are saddled with.

If you're game I would be happy to send you the re-programmed TCU to try out, or "guinea pig" in your Northern parlance.

Having used Power mode full time in my jdm car, I'm willing to bet you would be happy with the change it will make. Phil and Belha run their jdm cars all the time in Power mode. I'm fairly sure anybody who has done the Power mod in the US leaves theirs on all the time as well.

It just makes the car feel like a sporty drive. You get rid of the "lazy" feel that is there in the UK gearbox.

Do you want to try it? This is a one time only offer.

Joe

tempting Joe, and thanks for the offer

but the QC is more what I'm interested in, I like the idea of 'lazy' and 'sporty'

I remeber when I had the Small Car kit on, it was too aggresive for my liking.....not doubting that Phils wont be more refined, but not 100% what I would want to do if I played about with things.

got any more offers......Redbreast?

John

[oab_au]

Originally Posted by b3lha

OK. The Sol C duty cycle, that's what I expected. The main subroutine that calculates the duty cycle sets it between 5% (50:50) and 95% (FWD). I expect that the select monitor calculates the torque split on the basis that the duty cycle will alway be in that range.

But there is another subroutine appears to tweak the duty cycle a little based on throttle input. I think it is possible that on a rare occasion, the duty cycle may fall below 5%. This will upset the select monitor's calculation so that it shows 49:51, even though that is not physically possible.

The way I see it is that, the main routine that sets the C sol. duty cycle would be based on, throttle position, gear position, and road speed, these would be the normal running sets, that would be used to set the torque split.

Wheel spin would be an interrupt from a separate routine that compares the wheel speed front to rear, if it exceeds say, 20%, the base duty cycle would be increased, then checked for results.

You can't be sure that the torque split worked out by the select monitor, is a true representation of the pressure applied to the clutch, it depends on the line pressure that the A solenoid sets.

Harvey.

[svxfiles]

Originally Posted by oab_au

The way I see it is that, the main routine that sets the C sol. duty cycle would be based on, throttle position, gear position, and road speed, these would be the normal running sets, that would be used to set the torque split.

Wheel spin would be an interrupt from a separate routine that compares the wheel speed front to rear, if it exceeds say, 20%, the base duty cycle would be increased, then checked for results.

You can't be sure that the torque split worked out by the select monitor, is a true representation of the pressure applied to the clutch, it depends on the line pressure that the A solenoid sets.

Harvey.

Yea!
What He said.

[oab_au]

[QUOTE=blueji;581215]

Originally Posted by svxistentialist

tempting Joe, and thanks for the offer

but the QC is more what I'm interested in, I like the idea of 'lazy' and 'sporty'

I remeber when I had the Small Car kit on, it was too aggresive for my liking.....not doubting that Phils wont be more refined, but not 100% what I would want to do if I played about with things.

got any more offers......Redbreast?

John

Hi John, I can agree with you on the 'lazy' and 'sporty', bit.

My car is the same as yours, 3.7:1, VTD, and I am a 'normal' driver, but having riding Sports bikes all my life, I objected to the way the box changed back a gear, to do an overtake. It wasted valuable overtake time.

So I made the QC to fix the problem. Having said that, I am also doing Phil's ROM change to get Power mode, so I can use the gears a bit more and let the engine rev a bit.

The Small Cars kit was not the way to do it.

Harvey.

[blueji]

[QUOTE=oab_Au;581319]

Originally Posted by blueji

Hi John, I can agree with you on the 'lazy' and 'sporty', bit.

My car is the same as yours, 3.7:1, VTD, and I am a 'normal' driver, but having riding Sports bikes all my life, I objected to the way the box changed back a gear, to do an overtake. It wasted valuable overtake time.

So I made the QC to fix the problem. Having said that, I am also doing Phil's ROM change to get Power mode, so I can use the gears a bit more and let the engine rev a bit.

The Small Cars kit was not the way to do it.

Harvey.

Hi Harvey and thanks for the reply.

Just having recently got back into biking myself with a sports tourer the wife has kindly allowed me to spend all my pocket money on my bike just now, so if I do go for one of your inventions it wont be for a couple of months or so until the SVX is out of its winter storage

John