17 Accord Civic CRV CRX Del Sol Odyssey Prelude
88-98 88-98 97-98 88-91 93-97 95-97 88-98
VSS (Vehicle Speed Sensor)
defective circuit or unplugged / defective sensor

VTEC will not engage under 2mph or soemthing like that, so if there's a problem with your VSS, and the ECM isn't reading your speed correctly, that might explain it. Are you having any problems with your speedometer? I would check to see if it's plugged in, as well as check the VSS fuse under the dash.