Once tire slip is detected, electronic methods are used to reduce/degrade the engine power to the wheels. Up to a max of about 15 percent of an engine's horsepower can be reduced with minimal indication it is being done. Start to degrade more than that percentage and telltale indicators like sound (engine note changes), temperature of the exhaust (increases), or fire coming out the exhaust pipes (unburned fuel) begin to show up. A common method of degrading engine performance with ETC these days is by retarding the ignition timing-somewhere a distributor signal wire that triggers an ignition control to fire has to be tapped and the signal delayed. Sanctioning bodies are counting on finding or restricting that tap-in point, and ETC makers are just as determined to circumvent any barriers.

SOURCE
Davis Technologies
Asheville
NC  28814