Took my car out today for the first time. Twice I had the speedometer and Tach gauge sweep to zero and check engine light come on. I had my hand held connected, which froze after the gauges sweep with voltage at 12.1. I did not notice any change in car performance. After 2 seconds the gauges went back to normal. When the car is hot, voltage drops to around 12.4 but once you bleep the throttle, it goes to 13.5 or when the car starts running and things start cooling, voltage goes to where it should be. Right now I will run cooling ducts and see how that goes.