here's the deal: the "chip" is a resistor. half of the people on ebay selling this don't know what the value is. several people on this board have posted temp/resistance curves of the stock air intake temp sensor. for the ebay sellers who were willing to say what color bands were on the resistor, the performance chip is basically tricking the ecu into thinking its somewhere around 0-20 degrees F, causing the ECU to advance timing and drop more fuel because it is expecting air with a higher oxygen content, momentarily producting more horsepower. obviously on a 90 degree day, this readings are way out of whack. immediately after, you have one of the following conditions: detonation or check engine light.