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Hello guys. Newb here. I'm tunning a cbr1000rr 04. 1000cc NA inline 4 dohc 12:1 compression, staged injection, race headers, 98 octane, 12k rpm, direct ram air. This model got no knock sernsor, i have no access to a dyno. Running a piggy back power commander full setup with datalogging. i have basically every sensor in the ecu logging but got no access to the base map. Tunning the fuel with load on TPS sensor. So my question is its possible to make a ignition table based on map sensor reading. For example(ramdom numbers) i have -70 kpa with zero ignition advance at x rpm. I advance 10º and my kpa goes to -60 at that rpm. Does it work like that or there isnt any connection ? my idea is as i advance ignition timming (assuming im gaining power and torque) my VE is going up, so my map reading is going higher??
Aprecciate any help!
The power commanders only deal with the fuel side of things. If you're looking to tune it like you would with a car, you're going to need to have to get a standalone for that bike. Bikes are way different tuning wize than cars, at least with how the power commander works.
Tuning ignition via MAP will not be useful. You can find the MBT value at some low load areas this way, especially at idle, but beyond that it's not useful at all. Your best bet is to try to find an existing map on the internet for a similar engine.
I just checked the website and i stand corrected, they do have an ignition module. However, OP, you will not be able to find out your MBT without a dyno, also never jump up 10degrees immediately. You could be detonating and have no idea. I would do 2 degrees at a time, maybe to play it safe 1 degree. Not sure if you can put it into an auto tune mode that will help take over the ignition module, as far as street tuning from datalogging on the CBR, i would not mess with it too much, personally.
And by advancing the ignition timing that much at that RPM, its igniting your air fuel mixture a lot sooner. Raising combustion pressure. You could be past MBT at this point so you will be pulling less vaccum. -70kpa for instance is in vaccum. If you're bumping up to -60, you're essentially pulling less vaccum, which in my mind means your VE is going down. The more vaccum you pull in the lower rev range essentially the more air you're getting into it and the smoother it runs, up until you start getting into your powerband which then naturally starts increasing the KPA. However without an expert who knows more I'm not quite sure if I'm even in the right ball park with my theory.