Launch control

DDS · Post by **DDS** » Fri Oct 09, 2009 8:38 am

Launch control is precisely used to control at what rpm the car leaves the line (consistent drag racing)

Factory, some ecu's (ka24 comes to mind) let the motor rev to 6500 rpm, then cut the fuel until the rpms decel to 5500 rpm then repeat. It basically bounces. A much more useable rev limiter would keep the rpm oscillating points close together like 6500 to 6100 rpm.

Launch control would see an extra input grounded (clutch switch usually) and would impose a lower rev limiter than normal. several other tuneable ECU's like mitsu, subie, hondata, even bikiroms modify the ecu code to do this.

Turbo guys use spark cut since it passes unburnt fuel straight out to ignite inside the turbo manifold and spool the turbo rather quickly. With spark cut its easy to build close to full boost just free revving the motor. Also it makes nice foot-long flames and loud pops and bangs

This is of course hard on the turbo...

I love your idea 4x4LE, and I'm going to try it soon! I wonder if a negative number would work in that field for more retard? For example our KA24DET running Megasquirt I have set up to pull 40 degrees.

Legionnaire · Post by **Legionnaire** » Fri Oct 09, 2009 10:00 am

I always thought that launch control should be responsible not only for rev limit but also for elimination of wheelspin during acceleration.

If by LC you mean only several step rev limiter, it is doable and looks not very hard to implement, but let's see what Matt says.

So what you are saying is that for N/A users it does not really matter what kind of cut to use - its just rev limit level itself that matters and you generally want it lower when clutch is pressed.

For turbo crowd - don't antilag systems enrich mixtures/retard ignition some 40+ degrees? I don't see how just cutting ignition off with no load helps spoolup. What is the source of ignition for all the unburnt mixture in this case?

Petros.

DDS · Post by **DDS** » Fri Oct 09, 2009 10:36 am

Yeah, that's right. N/A it can be done, but gives no real benefit. As far as removing vs retarding the spark, its basically the same. The idea here is to purposely NOT burn the fuel (or delay its burning) while its in the cylinder. Force it to self ignite once it reaches the super hot temps in the exhaust manifold/turbo.

It is the same as anti-lag. In most cases I've heard it referred to as Flat-Shift. Mainly, if the car is standing still, build boost; If the car is in between shifts, build extra boost to maintain power output/eliminate lag. Mainly this is used in situations where a large, laggy turbo is used.

While testing our KA24DET, 2.4L with GT3271 Turbo (normally spools at 3500 RPM driving under load) I was able to generate 15PSI within 1.5 seconds free revving in neutral while a spark cut rev limiter at 3500 rpms was used. Plus it just sounded SEXY...

I'm playing around with some of the assembly code that ive disassembled here. I think that the 5th gear position switch and 5th gear rev limiter (speed limiter) could be used to do the whole launch control thing if the switch was changed to the clutch switch. Ill test it out maybe next week and we'll see.

Also wheel spin control would be more along the lines of "traction control". Pretty hard...

Matt · Post by **Matt** » Fri Oct 09, 2009 3:18 pm

it all depends on what engines etc are intended for this functionality

some of the code for S13 / S14 KA24DE already exists and could be ported. That is more of a specialist function which is usually tied in with particular ROM images. If I was expected to autopatch, thats where it becomes a lot more work

Also as it becomes available then people expect for different vehicles. Knock sensing was a good example. We got it working for selected vehicles and then I get continously asked when it will be available for other vehicles and those vehicles are completely different code and architecture

src · Post by **src** » Sun Oct 11, 2009 5:20 am

Matt,

Can you stop me where I go wrong?

I have grabbed deviouska's B13 Launch Control bin, also Launch Control XDF file from here: http://eccs.hybridka.com/viewtopic.php?f=21&t=1502

From what I've learned from XDF file, I added some lines to NisTune .adr file:

B13_SR20DE_256_E_91_92-LC.adr diff:

Code: Select all

+++
REV2_LIMIT,&H234A,2,1,2,12.5,Rev. Limit Normal (LC)
REV3_LIMIT,&H234C,2,1,2,12.5,Rev. Limit Launch (LC)
SPEED1_LIMIT,&H2349,2,1,1,2,Speed Limit (LC)
---
#REV2_LIMIT,&H0000,0,0,0,0
#REV3_LIMIT,&H0000,0,0,0,0
#SPEED1_LIMIT,&H0000,0,0,0,0

Now I assume, if I load LC bin with this address file I can modify the constants to get it worked... But no luck, then I start Nistune it says error:

Code: Select all

Address entry: REV2_LIMIT 0x234A (length 0x2) out of range. Ignoring this entry. Fix the address file to remove this warning.

Where I was wrong? Or it is depends on hardware/software/firmware???

Matt · Post by **Matt** » Sun Oct 11, 2009 4:41 pm

use the S13 KA24DE address file as an example

# Special parameters
LAUNCH_SPEED,&H2249,2,1,1,2,Launch speed
REV_LIMIT_NORMAL_IGN_RETARD,&H224E,2,1,2,12.5,Normal rev limit (ign retard)
REV_LIMIT_NORMAL_FUEL_CUT,&H224A,2,1,2,12.5,Normal rev limit (fuel cut)
REV_LIMIT_LAUNCH_IGN_RETARD,&H2251,2,1,2,12.5,Launch rev limit (ign retard)
REV_LIMIT_LAUNCH_FUEL_CUT,&H224C,2,1,2,12.5,Launch rev limit (fuel cut)
REV_LIMIT_IGN_RETARD,&H2250,2,1,2,12.5,Rev Limit ignition retard

are these the same memory locations?

src · Post by **src** » Sun Oct 11, 2009 8:24 pm

I'm trying these with no luck:

Code: Select all

# Special parameters
LAUNCH_SPEED,&H2349,2,1,1,2,Launch speed
#REV_LIMIT_NORMAL_IGN_RETARD,&H224E,2,1,2,12.5,Normal rev limit (ign retard)
REV_LIMIT_NORMAL_FUEL_CUT,&H234A,2,1,2,12.5,Normal rev limit (LC)
#REV_LIMIT_LAUNCH_IGN_RETARD,&H2251,2,1,2,12.5,Launch rev limit (ign retard)
REV_LIMIT_LAUNCH_FUEL_CUT,&H234C,2,1,2,12.5,Launch rev limit (LC)
#REV_LIMIT_IGN_RETARD,&H2250,2,1,2,12.5,Rev Limit ignition retard

The same error from Nistune. Ah, Nistune 0.9.13.1b - do I need to update this?

And the addresses have a minor difference &H22** -> &H23**.

Matt · Post by **Matt** » Sun Oct 11, 2009 10:05 pm

that is a later version. what is the error you are getting?

src · Post by **src** » Mon Oct 12, 2009 1:10 am

Matt wrote:that is a later version. what is the error you are getting?

Error1:

Code: Select all

Address entry: LAUNCH_SPEED 0x2349 (length 0x1) out of range. Ignoring this entry. Fix the address file to remove this warning.

Error2:

Code: Select all

Address entry: REV_LIMIT_NORMAL_FUEL_CUT 0x234A (length 0x2) out of range. Ignoring this entry. Fix the address file to remove this warning.

Error3:

Code: Select all

Address entry: REV_LIMIT_LAUNCH_FUEL_CUT 0x234C (length 0x2) out of range. Ignoring this entry. Fix the address file to remove this warning.

Log File:

Code: Select all

14:09:32.765 About to create MTS controls...
14:09:32.781 MTS1 Control OCX creation successful within this view
14:09:32.781 UpdateAllCombinationLists()
14:09:33.953 finished
14:09:33.953 ~CParser
14:09:33.953 Opening B13_SR20DE_256_E_91_92-LC.adr
14:09:33.968 ~CParser
14:09:33.968 NTLOOKUPID is 61
14:11:12.515 ConsultGetActiveSelections()
14:11:12.515 ~CParser
14:11:12.515 MyFileImgOpen: read_rom_Length 00008000 rom_length 8000 number 1

Matt · Post by **Matt** » Mon Oct 12, 2009 7:31 am

I've added address file bounds checking which is now causing those errors

Made some adjustments today to add overriding of these parameters. ie.

#Override default bounds checking
MAX_ADDR=&H2550

Also would be MIN_ADDR

These will be available in the next beta release when available

src · Post by **src** » Tue Oct 27, 2009 5:51 am

Ok,

No more errors with new version, but I can't find launch speed parameter in Nistune. Where is it?

PL · Post by PL » Tue Oct 27, 2009 2:20 pm

Hey guys,

Is there any reason why this cannot be implemented by just burning 2 images to a 27C256 and then use the highest order address bit to switch between the two images? One of my mates used to do this on his CA18 and it worked a treat. He didn't use it for launch control - just different tunes.

You could even go to a 27C512 for 4 maps. It's just that the switching gets a little trickier.

PL

src · Post by **src** » Tue Oct 27, 2009 8:53 pm

Pete,

Please describe me how do you want to switch maps? With an external switch to clutch pedal? Or I'm missing something?

Roman

Matt · Post by **Matt** » Tue Oct 27, 2009 10:24 pm

'LAUNCH_SPEED' is in there... what error are you getting?

src · Post by **src** » Sat Dec 12, 2009 4:31 am

I can't find launch speed parameter in Nistune. I have no error reported. Just can't find the parameter inside GUI.