Aprilia Falco Electronic Control Unit

The brains of the Falco engine management is an ECU made by Nippodenso. It's run by a 8MHz microcontroller reading code from a 32kB EPROM. Not exactly cutting edge technology when compared to a 3000 MHz Pentium IV, but it's more than adequate for an engine spinning its crankshaft at a maximum of 175 Hz (0.000175 MHz).

The Falco ECU, identical to the RSV ECU, reads many sensors in order to determine its outputs: injection volume (most likely duration) and ignition timing advance. Throttle position, engine speed, and manifold pressure are primary inputs to the lookup tables stored on the EPROM. The values read from these tables are used in an algorithm (also stored on the EPROM), along with secondary inputs of air and coolant temperature, atmospheric pressure and crankshaft position to calculate the desired injection and advance values.

I've tried as many EPROMs as I could get my hands on. Unfortunately, not always back to back or under the best test conditions. Here's a summary of EPROMs I've tried and a few comments. All worked well. If I had to pick one, I'd probably pick the Arrow as good performance for a value (especially with the RSC EPROMs running $200 each). I don't run it now because it is significantly leaner than stock at part throttles, so I'd like to check the exhaust gases on the dyno. The only one I've dyno'd was the RSC SL-Carbon chip, and with the stock air filter it was a good tune, perhaps a little rich up top but good near the midrange. This is the chip I ran until I tried the Factory chip. The Factory chip isn't cheap ($229 now that its copy protected?), but it is very smooth. My only complaint with it is that you need to warm up the bike to 120 F before you take off, or the throttle was choppy. This takes about one minute. Also, it required a bit of tuning of air screws and CO pots to get the idle back below 1700 rpm.

If you have a Javascript enabled browser, I've written a graphic utility to compare fuel injection maps. Pop-up blockers may need to be disabled to see this.

Other hints:

• The ECU has two pots for trimming idle %CO. The software for these is disabled in the US model bikes, so don't waste your time on them. If you have European chip, they work. They are enabled on the Factory chip, and the bike seems to idle smoother with the front cylinder leaner and the rear cylinder richer.
• There appear to be differences in aftermarket chips between derestricted and restricted mapping, so cut the wire even when using a non-stock chip. Factory sells a combination R13/R14 chip with minor differences. You can switch between the two maps with the destriction wire.
• RSC chips are useless without the daughterboard, and if you read them through the daughterboard they are still scrambed. The SL-Carbon and RSV-Titanium use the same daughterboard. BBPower chips reportedly use a daughterboard too. Factory chips, except the prototypes, use a daughterboard.
• If you happen to remove your RSC chip from it's daughterboard, you'll notice there is no pin 1 indicator. The silkscreened text "dibias"on the board should be on the pin 1 end.
• There's some guys pirating these chips now. Give your money to the people who develop the chips instead, and encourage them to keep up the good work.

See tips on EPROM installation.

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