At what rpm does a 2000 accord lx 2.3 go into vtec mode?

 

engine is F23A1 correct?

between about 2,800 and 3,500 rpm depending on throttle position.

 

F23A* VTEC engagement is based on;
Engine Speed - 2300-3200 RPM (depending on manifold pressure) give or take a few 100rpm.
Engine Coolant Temp - 50°F (10°C) or higher
Vehicle Speed - 6.2 mph (10km/h) or faster
Engine load - Based on intake manifold negative pressure (MAP sensor signals).

 

Ghost, sounds like that could be from the system description in the FSM.

I was pretty close. my information is based on what I've experienced driving the Accord. with an aftermarket intake or in my case with the resonator boxes removed, there is an audible change at the cross-over point. nothing registers on the "butt dyno," just a smooth transition as it was meant to be.

 

I know these specs off by heart now from posting it so much. You are correct they are from the manual.

Yeah the VTEC system in the F23A and F22B1 are definitely more for economy. Only one valve is fully open when VTEC is not engaged. The other valve only partially opens in order to keep fuel from pooling behind it.

If you have a B1 or F23 camshaft nearby you can measure the lobe and see the difference.

F22B1 lobe heights;
Primary = 37.7mm
Mid = 39.7mm
Secondary = 34.5mm