Launch by time

This section is dedicated to discussion of DTA engine control units such as the DTA E48 EXP, P8 Pro, DTA S40, S60, S80, and S100, as well as all things ECU related.
SMR
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Re: Launch by time

Post by SMR »

I think Stevie is right - This does ring a bell - pretty sure only one driven wheel is logged /looked-at during launch phase. Until the turn-off speed has been reached.
Alex DTA
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Re: Launch by time

Post by Alex DTA »

Rob Stevens wrote:Alex, please can you explain how the undriven wheel speed interacts with launch vs time a little more. I can't see anything in the instructions. I've been waiting for launch rpm vs road speed for years and have been turning the pot down manually once moving, could this do the same for me?
Wheel speed is not used in launch by time.
Previously, the assumption was that launch by time meant no wheel speed sensor.

As in this case, launch by time is being used, but with a wheel speed sensor required to modify boost.

In firmware 79.06, a modification was made to ensure the wheel speed was calculated with launch by time.

Launch RPM vs road speed is not available. Where would that be used?
Alex DTA
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Re: Launch by time

Post by Alex DTA »

SMR wrote:I think Stevie is right - This does ring a bell - pretty sure only one driven wheel is logged /looked-at during launch phase. Until the turn-off speed has been reached.
Correct. This is because the same code is used for the S40, which only has one wheel speed input.
Rob Stevens
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Re: Launch by time

Post by Rob Stevens »

Alex, if I launch at say 5k I want to get onto the launch traction phase quick as possible so I reduce rpm with the knob by hand. I cant set off with less rpm as it stalled. Others like motec can do this.
Rob Stevens
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Re: Launch by time

Post by Rob Stevens »

Also I'd like the launch to have an option to work in one gear only, not just turn off on road speed. If I change into 2nd early I'm stuck with massive wheel spin until the traction can pick the job up.
stevieturbo
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Re: Launch by time

Post by stevieturbo »

Alex DTA wrote:
Rob Stevens wrote:
Launch RPM vs road speed is not available. Where would that be used?
During launch ?

Ideally you want a variable slip target during the launch phase. Whether this ramp is based by speed, rpm, or estimated via time....lots of options.

But clearly at the initial phase of launch you need a high slip target, simply to ensure it wont bog down and as it progresses that slip target would become tighter.

With an rpm ramp you're sort of estimating what you hope the slip target to be. With say 4wd cars, time might be a better ramp to use vs rpm because all 4 wheels may be spinning.

DTA tries to use an rpm ramp and a calculated speed.

But as has been mentioned, it is very annoying that some actual wheel speeds are ignored during launch and calculated or substituted values used instead, which makes it harder to interrogate the launch phase via logging, as you are not seeing real numbers.
Wheel speeds should always reflect wheel speeds.

If you want to add the calculated field for the launch/gearing/speed field, that may also be useful too.

For the boost aspect...it seems the boost vs speed is based on vehicle speed...which is driven or undriven ? Clearly driven with lots of wheelspin would be bad, as boost may ramp too quickly with wheelspin which is actually counterproductive
Boost ramp vs time or undriven speed would make more sense for launch
rocar
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Re: Launch by time

Post by rocar »

I use undriven speed to control boost by speed.But is I use launch by time speed do not work.
So I can't use both, I need launch by time and undriven speed for boost control,I use speed on Aux to control other things so speed is indispensable
Alex DTA
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Re: Launch by time

Post by Alex DTA »

rocar wrote:I use undriven speed to control boost by speed.But is I use launch by time speed do not work.
So I can't use both, I need launch by time and undriven speed for boost control,I use speed on Aux to control other things so speed is indispensable
You can. Undriven speed is calculated as long as you have v79.06 or higher, which was released about 4 years ago.
Alex DTA
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Re: Launch by time

Post by Alex DTA »

Rob Stevens wrote:Alex, if I launch at say 5k I want to get onto the launch traction phase quick as possible so I reduce rpm with the knob by hand. I cant set off with less rpm as it stalled. Others like motec can do this.
Ah, I understand now.
There are various ways of doing this. Different RPM targets, different slip targets, etc. I will be implementing something for the new ECUs when I get to the launch control.

The new ECUs will split everything out. If you have wheel speed sensors, speed will be calculated. You can then use that for speed only, or launch, or traction, or boost by gear, etc.
No need to turn anything on, and only have one of them being calculated.

Needless to say all this will require testing, so I'm pleased you've all stuck your heads above the parapet and nominated yourselves. :)
rocar
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Re: Launch by time

Post by rocar »

Alex DTA wrote:
rocar wrote:I use undriven speed to control boost by speed.But is I use launch by time speed do not work.
So I can't use both, I need launch by time and undriven speed for boost control,I use speed on Aux to control other things so speed is indispensable
You can. Undriven speed is calculated as long as you have v79.06 or higher, which was released about 4 years ago.
V79.06 ECU version or Software Firmware ? As I tried it with v89.00 software on an S80 and did not work but I will try it on other Ecu soon

Thanks
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