2014 Chevrolet Corvette: Engine Braking and Rev Hanging
November 21, 2013
When you lift off the throttle in our long-term 2014 Chevrolet Corvette, not a whole lot happens. The engine essentially freewheels for what seems like a few seconds. Then, finally, you get the engine braking you were expecting, and hoping for.
This "rev hanging" phenomenon is an undesirable byproduct of the engine calibrator's attempt to clean up the emissions of the Corvette's 6.2-liter engine. Basically, by keeping the throttle open during the overrun (you lift off the pedal, the injectors are switched off), the throttle stays open to allow fresh air into the cylinders to help oxidize unburned hydrocarbons. While it is effective at this scrubbing task, it also scrubs engine braking. Bew.
The C7 isn't the only car to exhibit this trait, but that doesn't make it any better. Usually what happens is that the automaker gets enough customer complaints that it issues an ECU reflash with revised throttle mapping to reduce the rev hanging. Or they make a running ECU program change along the way. I expect GM will follow a similar pattern with this car.
For kicks, on the complete opposite end of the overrun-engine-braking spectrum, the car that's hyper-willing to jump into full engine braking at the slightest hint of a throttle lift is the Ferrari 458 Italia. It's almost disconcerting. And now you know.
Jason Kavanagh, Engineering Editor