Review on Optimize Your Hyundai Sonata's Performance with the Revolutionary Chip/Power Programmer - Compatible with 1.6L, 2.0L, 2.4L, 2.5L, 2.7L, 3.0L, and 3.3L Engines - Enhance Fuel Efficiency, Save Gas, Boost MPG, and Amplify Horsepower and Torque! by Luis Blaschko

Idling caused initially. It eventually stopped but stayed at a higher RPM than before installation. I haven't seen any improvement in mpg. I even traveled for a month as a grandma to see if it helped and still no result. I contacted the manufacturer to make sure I installed it correctly. He made sure I did. I drive a 2006 gls sonata. As a result, my car stalled and would not start. I removed it and everything is back to normal. upset.