i have a code 43. i have replaced the ESC module with another used unit. i suspect the knock sensor has failed. how do i test it? i know a knock sensor retards the timming but i dont know how. how does it work and what makes it fail. can a knock sensor make the car idle funny at times? sometimes the idle is really poor.

 

A knock sensor is a piezo electric crystal that puts out a voltage at a certain frequency, which is tuned from engine to engine to be the frequency that knock produces. The ESC module conditions the small voltage output at the knock sensor and turns it into a signal. When no knock is detected, the output is about 8-10 volts to the ECM. When the ESC module detects a kock, the signal is pulled low, and the ECm retards the timing after a certain number of knock counts have been observed.

IF your knock sensor has failed, you wil lose power because the ECM will pull timing when it isn't needed.

However, I am not sure if the knock ESC is even active at idle? Anybody know?

 

what is the proper test procedure to test the rest of the circuit. i tried hooking up a wire to the knock sensor lead to ground(engine block). had no effect. does this mean that there is a problem elsewhere? are your supposed to hook the lead up to the hot side? can the knock sensor voltage be read with a multimeter? in order to test for a knock a rpm drop should be noticed when the system is triggered. am i correct in that assumption? should i invest in a ALDL cable? would that give me more diagnostic information? if my knock sensor is bad, it will get replaced. i want to make sure that is the problem before i purchase a new one. i still dont know if that is causing my weird idle problems. sometimes the car idles good, however sometimes the idle is terrible. tach will more 300 or more rpm up and down. the best way to describe it would be loping. its quite annoying and i would like to fix it. car is completely driveable. its just an annoyance for someone that is mechanically inclined. i dont like to ignore little annoyances. could i have a bad IAC or TPS and it not illuminate the check engine light? i would be greatfull for any advice.