The LT5 secondary intake port valves live in an unusual environment. When the port throttle is closed, the valve is in dead air and there is no fuel flow. When the secondary port intake valve opens, the back of the valve, the fuel injector and the port are exposed to compustion gases due to reversion. The primary valve runs clean because fuel with detergant additve washes it down. If the car is driven lightly the secondary ports are closed most of the time. Without the fuel's cleaning action the valve deposits build up. In the case of this engine the deposts were able to build to an epic level.

The valve from the primary port is clean.

Normal spririted use of the car with wide open throttle use to 7000 rpm cleans the valves and the combustion chambers.

This situation can also be minumized by doing what I call, "Running on the Secondaries".