all high compression cars, especially OBDII vehicles do this to prevent detonation during high temperature environments.

this is performed by the Intake Air Temperature (IAT) sensor. when the air intake temps are higher, the air is less dense and therefore more prone to detonating the fuel charge. the IAT allows the ECM to properly redistribute fuel and/or alter the timing maps to prevent detonation/knocking and also in conjunction with the O2 sensor and coolant temp sensors, keep the motor operating cleanly, even at a loss of output.


technically speaking, you can cut the IAT sensor lead and install a resistor of the right resistance so the ECM receives a signal simulating a 70 degree intake air temperature, thus preventing the ECM from retarding the timing on a hot day.... but it may result in knocking/pinging/detonation on a hot day. you can measure the range of the sensor with a backprobing ohm meter to help you find the resistor to meet your demands.

also, 96-97 Preludes have known knock sensor and other emissions control issues and had their warranties extended to 14 years/150,000 miles. you may want to have the dealer check it out if you run into problems accomplishing an emissions inspection.