Powers Pages - 2004 Honda Civic Si EP3

The A'PEXi S-AFC NEO, designed as a piggyback fuel controller, incorporates both previous model S-AFC and V-AFC functions into one simple-to-use unit. Tuning options have been upgraded with the Neo as 32 points of tuning (16 low and 16 high) overpower the previous AFC II unit, which used 24 points or 12 low and 12 high. A scroll through the main menu options on the controller will send you to a mode select screen where the user has the option of selecting between "easy" mode and "pro" mode. The easy mode features an eight-point low and high adjustable fuel curve, while the pro mode can custom tailor your tuning with a sixteen-point low and high adjustable fuel curve that can be set in 500 RPM increments-versus 8 and 12 on the earlier AFC and AFC-II, respectively.

If reading wiring diagrams and dealing with electrical components cause you to have anxiety attacks, perhaps you should leave installing the NEO to a more qualified mechanic. Tuning the NEO requires a dyno and skills to properly test and tune when looking to extract the maximum horsepower potential.

AFC, instructions, wire harness, connectors, adhesive tape

Crimpers, pliers, electrical tape, solder and iron

45 minutes

Browsing the web enabled us to come across a site called Boomslang Fabrication which specializes in plug and play ECU sub-harness and connectors for many of the more popular aftermarket electronics ranging from the GReddy e-Manage to Power Enterprises Camcon unit. Boomslang saved us the headache of wiring in the NEO by supplying us with a simple sub harness connector that connected our NEO within seconds. With the NEO in working order, we began adjusting the fuel curve on the Civic by carefully leaning out the mixture at lower rpms. The same theory was applied at 4500 to redline but the K20A3 seemed to reject our new settings as power output was lower than our previous run. A few taps of the NEO and we found a perfect setting which helped to net a consistent gain of 7hp and 5 lb-ft of torque from 6400 rpm to redline. Experimenting with the i-VTEC and raising it from the factory 2300 rpm to a higher setting proved no benefit in creating power. We decided to lower the setting back down to 2200 rpm which seemed to work best with our Civic.

A'PEXi S-AFC Neo
Peak HP 154.0 / Peak TQ 133.7

Horsepower Gain
1500 to 3500 HP range: 1 to 3
3500 to 5500 HP range: 2 to 4
5500 to redline HP range: 5 to 7

Torque Gain
1500 to 3500 TQ range: 2 to 3
3500 to 5500 TQ range: 3 to 4
5500 to redline TQ range: 4 to 5

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