real time adjustments

[fikemoo]

Hello there guys, mapping the car yesterday with the aid of logging we were trying to adjust the VCT to get it right for fuel economy and the state of tune that the car is at, we noticed while cruising it was just flicking in and out continually, say for example if you put your foot down the VCT will stay active its not always flicking in and out, just when you modulate the throttle at the low end. so we set out about changing the load value to something a little bit higher. But changing any of the values did not seem to have any effect on how it performed (this was being done in real time as the car was being driven hence the title of the post)

Question is really:

1. Can you adjust the VCT inputs whilst nistune is live? its the only thing i could think of as to why it was making no difference with any input that we put in/
2. Also as a side note really, has anybody else experienced problems with a LC-1 wideband, it dropped out yesterday when mapping the car and nistune seemed to have a fatal crash, we are not sure if nistune crashed and caused the wideband to disconnect or the other way round, and since this we have not been able to reconnect the wideband.

Thanks Mike

[Matt]

Which ECU are you tuning? Z32 ECU?

There is hysterysis in the code to allow for difference between VCT on/off at a certain load and PRM points.

1. When making changes they are live, even for VCT. However remember there are certain conditions behind the VCT on/off set so after making the change, stop the vehicle and then take off again (for speed to reach 0). Also making sure when changes are made you see 'uploaded' at the bottom panel

2. Yes I've had LC-1 drop out before and have had to unplug/replug the device, or stop and restart the car to reboot the LC-1

With crashes... since LC-1 are serial most people will use a USB-serial converter... this is the kicker. If you use a quality branded converter cable like one with a legit FTDI chipset for example then the drivers will be solid.

However if you purchase cheap converters like some of the junk on ebay they use cloned chipsets (eg prolific chips are very often cloned) and the drivers are dodgy. They are likely when they crash to take the whole PC down. In this case you will need to restart the PC

[fikemoo]

Hello there matt thanks for the usefull information.

Yes the ECU is a z32, and we will check for the points you have mentioned, next mapping session we plan to set the tp activation point at 35 when the car is at a stand still, the next question is;

1. Does the TP input have a direct correlation to the actual TP? as from the last session we noticed the TP input was set to 28 but the VCT was activating around 18 to 20 actual TP, hence why the VCT seems to be acting rather like a switch on low load driving a slight touch of the throttle and it will come on and a slight lift it turns off

Thanks again Mike

[Matt]

There is normally some hysterysis used

D19E : FE 14 17 ldx TP_COPY1 ; gets TP value
D1BE : 18 xgdx
D1BF : 7B 20 C1 tim #$20X00C1 ; checks VTC hysterysis flag
D1C2 : 27 02 beq LD1C6 ; not set
D1C4 : 8B 10 adda #$10 ; If it was set then add 16 (offset)
D1C6 : B1 F9 F7 cmpa VTC_TP_CUT ; compares against your TP cut parameter
D1C9 : 25 05 bcs LD1D0 ; TP < VTC_TP_CUT
D1CB : 72 20 C1 oim #$20X00C1 ; Set hysterysis flag
D1CE : 20 03 bra LD1D3
D1D0 : 71 DF C1 aim #$DFX00C1 ; Clear hysterysis flag

So once TP goes over the VTC_TP_CUT the hysteresis flag is set to +16 the value you see to switch it back off again

[fikemoo]

So if the activation for the VCT is set to say TP 30, the TP value the ecu reads when VCT enables would be 14 or have i got that wrong?

thanks again Mike

[Torque]

Hi Matt,

What's VTC_TP_CUT?
Never seen a TP based VTC cut on Z32.

There is VTC_RPM_CUT

Cheers

[Matt]

Range is TP ... TP + 10 < TP_CUT

So with TP = 35 then it would be TP_CUT range 25 .. 35

Andrew - VTC TP enable register

[Torque]

Ahh
TP_CUT = TP_ENABLE?

[Matt]

yes... in my assembly it was called this