Thread: Using IGN cut for Launch Control
11-20-2009, 06:24 PM #1
Using IGN cut for Launch Control
We'll I posted some questions on the Motec PWC forum but not much going on over ther so I'm reposting here where there is a little more traffic
I recently prurchased an M400 for Sea-doo RXP-X and wanted to setup launch control. This ski does not have DBW so this would need to be accomplished with Ignition timing cut to reduce power. I'm new to setting up these ECU's and the learning curve is steep so please bear with me. I went to the Ignition compensation tables and found that Comp 1 was already in use so tried to setup Comp 2. I setup the X axis to be TP but I could not define a Y axis in Comp 2. It appears to me that Comp 2 is limited to a one dimensional table or maybe there is another setup option that I don't know about ?
Second question is in regards to what to use on the Y axis. The presentation I saw from PeteS shows the Full Throttle Timer on the Y axis. To me it seems that the Digital Input from speed sensor would be better as it would then only intiate launch control when accellearating from a low speed. There is no wheel spin on PWC so the digital speed sensor will always read true water speed. Has anyone tried this method ?
Last question is how do activate a compensation table from an external switch/button ?
11-20-2009, 06:25 PM #2
Here was my answer to myself:
Well I have been able to answer some of my questions so I will post what I think know so far:
1.) Iginition Comp 2 table is one dimensional and therefore can't be used to cut ignition based on throttle position and full throttle timer or water speed ( i.e. you can't use Ing Comp 2 table for launch control ). So You would have to use Ign Comp 1.
2.) It appears the only way to use a switch / button ( digital input ) to enable launch control would be with a three dimensional Comp table which doesn't appear to exist for Ign. The other approach would be to use Comp 1 with y axis having two values digital input high / low and x-axis being water speed. This approach would then eliminate the throttle position input but you could disable with switch if you're not planning a full throttle launch.
My conclusion is that throttle position translation table with DBW is a much better way to implement launch control compared to ignition cut but not all PWC's have DBW functionality.
Anyone feel free to jump in and let me know if I'm missing something.
11-25-2009, 07:59 PM #3
Here is the reply I posted on the MoTeC forum.
Ok we have a couple of things on the change at the moment
The first one is there will be a new start file that will make available ign comp 1
We have moved the existing alarm trigger table from comp1 and put it else where.
That said I believe you can still do a reasonable job of launch control using ign comp 2 and the 2 d table.
To start with I would not use the factory paddle wheel as this sensor is too unreliable, you will find that it often drops out due to the paddle comming out of the water.
You could use a GPS but this relies on you having one and that it can see satilites (sometimes a problem) also not legal in stock class.
So here is how you could do it.
Using the Y axis on Comp 2
allocate the full throttle timer to that and increment it up in .2 second spacings from 0
Then simply enter the amount of retard you want to apply at each point after the launch.
I would start with something like this
0.0 = 0
0.2 = -10
0.4 = -15
0.6 = -15
0.8 = -12
1.0 = -10
1.2 = -5
1.4 = -2
1.6 = 0
1.8 = 0
2.0 = 0
It will obviously depend on how much ign timing you have in the main table as to how much you will need to pull out to get rid of enough power
It will be a trail and error thing using the logging.
Make sure you adjust the full throttle timer reset delay to 9 seconds so that the launch mode doest reinitiate on the race track.
Misc Set up
Full Throttle reset Delay = 9
This method only really works for racing as if you go below full throttle for more than 9 seconds then this will start the timing retard again on the next application of the throttle.
I know thats a bit confusing but once you get in there and start having a play it will all become clear.
MoTeC Research Centre, Melbourne Australia
PeteS Posts: 29 Joined: Mon May 05, 2008 4:04 pm
11-26-2009, 07:48 AM #4
Thanks for the info. I'm not racing currently and only using this ski for rec use so GPS input is an option. Let me know when you have the new mappings ( no rush its cold here ! ).
04-30-2010, 01:40 PM #5
- Join Date
- Feb 2008
05-03-2010, 06:51 PM #6
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