Tuning Your Vehicle

The best way to tune a vehicle is using a dyno. When using a dyno for tuning, the primary concern is to maintain consistency between runs by limiting the environmental factors which affect power. For this reason try to start each run with the same coolant temperature and air intake temperature. Try to maintain the same time interval between dyno runs.

For engines with variable valve timing (VTC), the tuning process is a little different from tuning any other engine. The best process is outlined below.

1. Start by tuning the low cam. To make the ECU use the low cam, change the VTEC parameters so that the VTEC point is high. You only need to perform dyno runs to a point above the expected VTEC point - normally 6500 rpm is sufficient to tune the low cam tables. Do not run the engine to high rpm (over 7000 rpm) on the low speed cam otherwise the lost motion assemblies can float, damaging the spring retainers.

2. Lock the cam a single angle. First find what cam angles your calibration uses - normally it will be 0, 10, 20, 30, 40 or 0, 15, 30, 40, 50 degrees.

Cam angles

Starting at the first cam angle, lock the cam angle to this setting by setting the low speed cam angle table to this value.

Cam locked to 15 degrees

3. Tune the fuel for this cam angle until the measured AF ratios are acceptable.

4. Tune the ignition for this cam angle. Generally the default ignition settings are close to optimum.

5. Copy the fuel and ignition tables from this cam angle table to the next cam angle table so that the next cam angle has a tuned starting point.

6. Repeat for the next cam angle by locking the cam angle to the next value, and return to step 2.

7. When finished tuning fuel & ignition for all cam angles, tune the VTC to generate a composite cam angle table.

You should start the dyno run just past the VTEC point, and continue to redline. Repeat steps 2 - 7 for the high speed cam.

•	It is more productive to first tune the cam angle when the engine will make the most power - usually 30 degrees. Once the 30 degree fuel & ignition tables are tuned, copy the 30 degree values to both the tables above and below, then tune the remaining tables.

•	The VTEC can be smoothed by advancing the VTC cam angle just before VTEC so that the jump to the high cam requires less time for the VTC to advance the cam. See VTEC point tuning

•	For fuel tables make changes by selecting rows. This will ensure that the part throttle fuel will be adjusted based on the full load lambda readings, and so will require less part throttle tuning.

•	For forced induction start by tuning on the minimum boost level. A turbocharger wastegate or supercharger bypass can be held open to allow tuning of the atmospheric pressure columns before tuning the boost columns. Never disconnect intercooler pipes as this will overspeed a turbo.