Just installed the VAFC last week with everything zero'd out (thanks RayN). Today, I drove around with Vtec Input and Output as the monitoring channels and played with various engagement points.

I noticed that the stock ecu signal for hi-cam engagement and disengagement is not only rpm independent, but also is based on engine-load. For instance, you can "gently" roll into the high RPMs w/o the hi-cam ever engaging, and, you can also disengage the hi-cam at high RPMs during extended lifts.

Additionally, when I heel-toe/double-clutch (throttle blips send the rpm over vtec signal point), the stock ecu will NOT send a signal to engage the hi-cam, whereas the VAFC will.

It appears as though VAFC is purely RPM-dependent. The ECU, on the other hand, has some "intelligence" built in.

The questions that comes to mind is why did Honda introduce multiple variables into the hi-cam engagement/disengagement algorithm... Reliability? Economy? Wear/tear?

(search function was down at time of posting, so could not verify if this had been previously discussed)

Stephen
'02 Suzuka

past toys:
'98 Eclipse GSX - BPU winter/offroad drifter
'94 Supra Single Turbo - T04R, 600+ RWHP
'94 Miata T3/T4 Turbo - 380RWHP

 

I think that Honda designed it that way for several reasons.
- Reduced wear on the VTEC solenoid
- Reduced noise
- Fuel economy
- Overal longevity

 

display the MAP reading and you'll find a correlation with VTi. If the engine doesn't have enough air pressure to run the high cams then it may be damaging to the internals. Also, if you're only at partial load then you don't need the power of the high cams.

 

I don't think the ECU disengages VTEC every time the throttle is lifted, so I don't see how it would really be damaging to the internals.