I have a 94 accord ex f22b1. My vtec and speedometer works periodically but they only work if both of them are working. I have tried several speed sensors and vtec solenoids. How are the two related and what can I do to make them both work? Thanks for any info on the problem...

 

I think the relationship is that the ECU won't engage VTEC unless the VSS shows some road-speed. So I wouldn't expect the VTEC solenoid valve to be bad.