Thread: Perfecting your tune
01-05-2013, 08:21 PM #1
Perfecting your tune
Once the EFI ECU has been chosen and installed (weather the ECU was reprogramed, or totally replaced), how are you guys verifying that the tune is dialed in thru the entire operating range of the motor?
I would think that the number of guys that have unlimited access to a watercraft dyno is relatively few.
01-05-2013, 08:48 PM #2
the best way is to use a afr gage
you can not change the map on most ecus
but it will tell you if you have any fuel problems
01-05-2013, 08:51 PM #3
01-06-2013, 03:01 AM #4
01-06-2013, 08:11 AM #5
I find it interesting that people don't post their logs here. On other sites I hang out on, people insist on seeing data logs before posting answers and advice. It is amazing what you can see in the logs.
As an example in the Harley world, they have a Y type shared intake manifold. When the rev limiter goes active, fuel is pulled from the front injector only. The other cylinder goes into a huge lean misfire. I found in the waterski world, that when the rev limiter is active, the O2s are reading huge lean from the fresh air being pumped thru the motor by the activation of the rev limiter. This was leading the owner to keep adding fuel to the active cylinders. Those cylinders were going into a rich dead miss. When the ski got back into the water, it had to clean itself up before making clean power.
I tend to find that the company's that build the hardware and software like it better when their tech support time can be spent on the more challenging installs.
When people share their knowledge and observations, everybody learns faster. Any more, getting the keys to the kingdom is cheap making reading the data easy.
01-06-2013, 08:48 AM #6
Here is an example of data from a totally stock RXP-X coming off a dyno
Notice how dangerously lean the ski is and how little of the fuel map is being hit.
Now look at a modified ski plotted in the same scale when operated on a lake.
The dynamic range of the motor found on the water is way different than what is seen on the dyno. I see this all the time in the motorcycle world. "My dyno guy got this WOT plot on his dyno and look at how much power he got. He tells me it is perfect". You get the bike on the data loggers off the track and the bike is a fueling mess.
Last edited by whittlebeast; 01-06-2013 at 09:43 AM.
01-06-2013, 09:48 AM #7
It is easy to dyno a bike and very hard to do on a ski like we ride them
The loss of traction is very common on our skis at full boost and then full load back on in a flash (boats only)
If you cut fuel only when the load hits at full boost the motor may go dangerously lean
and with no boost fuel cut is no problem
I use a timing cut using the rate of rpm increase first and then the fuel cut so the advance is lowered when the load hits again
This soft rpm limit can work without a fuel cut but not most of the time
IMO those color charts suck compared to a line chart like this
I have a logs of the advance and fuel % on a rev limit run
01-06-2013, 09:23 PM #8
Andy converted my motec and a vipec log file into one of those color maps
I can now see that it can make a long log into one simple graff that can be another good tuning tool
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