check engine light

[benja]

why would a knock sensor trip when the check engine light is triggered? After my headers were instaled my check engine light came on, and i know why. however my car was running like doo doo so i dynod my altima (01) and i got an awsome 117 hp and 127flb and i was lean as hell. after a stillen high flow intake a cat back apexi exaust and stillen headers and race pipe this is rediculous! so we ran a diagnostic and found out that the knock sensor was tripped an it was sending funky signals going lean and rich lean and rich i admit i know nothing of whats happening to my car. stillen sent me a black box and it should fix the check engine light but will it send the knock sensor back to normal operation giving me my power back? or is this a new problem i will need to address.

[nismo96ka]

ok well first of the knock sensor will NOT set the check engine light on your car. anybody wanna argue with that? kiss my$$$ anyway 2nd of all the knock sensor doesn't send rich/lean signals... the Oxygen sensor does that. The knock sensor is designed to pull timing not fuel.... but yea those dyno number do suck... mine put down more then that when it was STOCK.

[l31nismo]

Actually on 90 and 91 model 300z's a knock sensor will throw a ses light. But you are correct about the o2 sensors. They read the exaust gas and tell the ecm, "engine control module" wether to lean out or enrich the air fuel mixture. By removing your "pre-cat's" you caused this problem. The knock sensor is going off because your car is "pinging" from the jacked up fuel mixture. You either need to re-install your pre cat's or get a mil eliminator kit. You can find these from sites like, http://www.mossyperformance.com. Your check engine light is causing your low dyno stats because it sends the car into kind of like a "limp home" mode enriching the fuel mixture. If I were you I would just get the mil eliminator and keep kicking ***.

[nismo96ka]

yea i know it will set the light on the 300zx...but his car's an 01...an OBDII vehicle...90 and 91's are what we call OBDO.... lot of difference there.

[benja]

Thank you all for your imput its nice to have you. Here's an update, the 02 sensor was changed out(at cat)and I did regain some power.Then ran another diagnostic and the 02 sensor problem was gone but the knock sensor was still an issue, so I replaced that one as well, and to my relief it was no longer an issue.we also installed the black box via stillen and hooked the 02 sensor to it.the only thing the diagnostic picks up now is the 02 heater circuit which should be an easy enough fix, i'll replace the 02 sensor and hook up the box to the new one and hopfully the check engine light will be off.but my car is running awsome just got to get that light off.