Project Cappuccino: Testing the Kei Sport USA PNP ECU

The 25 year laws in the US have had a funny effect on JDM cars: the value of Skyline GT-Rs has shot through the roof and so many owners want to restore and maintain their cars that Nissan and NISMO have restarted production of service parts for these cars.  Toyota, through their GR Sport division, is making continuation parts for the AE86 platform.  The prices for old kei cars has increased as well: Cappuccinos and Beats have both jumped a few thousand dollars in price thanks to the internet fame brought by Regular Car Reviews, Doug DeMuro, Everyday Driver, Hagerty, and of course MotoIQ.

Suzuki Cappuccino & Isuzu Vehicross
MotoIQ: Choosing weird old Japanese cars before they become cool again.

Unfortunately, Suzuki has not decided to restart production of service parts for the EA11R chassis.  Likewise, Monster Sport (Suzuki’s tuning arm) is actually winding down production of many of their Cappuccino specific parts.  The good news is, new companies are springing up to fill the void.  One such company is Kei Sport USA.

Kei Sport USA is a small shop located in Royal Oak, MI.  They are big fans of tiny Kei cars and are putting new aftermarket parts into production for the Cappuccino, the Honda Beat, and the Mazda/Autozam AZ-1.  Their first big project has been a standalone EMS system for the Cappuccino.  They are also big fans of MotoIQ and when we reached out they were more than happy to send us one of their units to try out!

Cappuccino 3/4 ShotA PNP ECU for the Cappuccino is actually quite difficult.  Suzuki uses a lot of odd and archaic techniques for its EFI system that require some creative work.  For example, most EFI cars use a potentiometer type throttle position sensor.  As the throttle blade rotates, the resistance of the TPS circuit changes, reading as change in voltage by the ECU, thus telling the ECU how much throttle the driver is using.  In the Cappuccino, Suzuki uses a three position switch which provides very limited resolution to the ECU.  Suzuki also chose to use two pinouts for the fuel injectors instead of three.  This forces the number 1 and 3 injectors to have the same timing and duration, thus limiting overall tuning potential: for example, if Cylinder 3 runs a bit hotter and we need to use more fuel to keep it from detonating, we must also do the same for Cylinder 1 which could make it too rich and lower its power output.  It is likely Suzuki designed the EFI in this way for cost cutting since the Kei car class is designed to be very cheap (fewer injector outputs on the ECU means less wiring, a cheaper connector, a cheaper PCB, less processing for the CPU, etc), but it does provide some challenges for a more modern EFI solution.

The Kei Sport USA Plug and Play (PNP) system is a simple enough idea: take a Megasquirt Module and adapt it to a custom PCB that fits into the Cappuccino’s original ECU housing and plugs into the original wiring harness via the factory connector.  Kei Sport USA has spent a lot of time ensuring that all of the Cappuccino’s original Inputs and Outputs (I/O) are compatible with their adapted Microsquirt Module.  EFI Analytics Tuner Studio is used for both map changes as well as data logging.  The concept requires zero wiring and only the bare minimum of electrical knowledge to install.

Monster Sport N1 ECU Kit
For decades the best ECU upgrade for the Cappuccino was Suzuki Sport’s N1 ECU (now continued by Monster Sport). The N1 ECU was a simple reflash of the original ECU to allow for more boost and more ignition advance using high octane fuel. While this would indeed net a few horsepower, the gains would be fixed as it was a one time flash with no scope for additional tuning. To make matters worse, this also relied on the ancient ECU Suzuki designed in the late 80s which has limited processing power and memory. A lack of memory and a lack of processing power limits the fidelity of the tune which can result in poor driveability. Source


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