effect of no VSS signal

[squared]

What is the impact of not having/using VSS on PCM operation? I see that it's a flag for idle zone entry, but does it effect fuel/spark calculations above idle speed? For example during steady state operation at above idle rpms and throttle openings, or during transient conditions during accel/decel.

[workingdog]

My understanding is no. Although it might on new cars. I'm working on stuff that is over 10 years old. Early 2000's stuff speed isn't used for much. What vehicle are you working with?

[cobaltssoverbooster]

you dont need vss but if you run say an older drag racing transmission, like a 1500+ hp powerglide that doesnt have a vss option, then you would at a minimum still be required to wire in a switch that notifies the ecu when the transmission is in gear. most just use the neutral safety switch from an aftermarket shifter assembly to send the signal to the ecu.