Weird knock sensor problem...(wiseman look)

[firebirdvert305]

OK guys i gotta 93 fwd laser i was driving along and the CE came on code 31 knock sensor i replaced the knock sensor (itself looked like the black gooey part started to drip but most of the goo was still intact but in bad shape.) Well my knock problem and CE light have been solved Well now onto my friends 91 awd talon, since we changed my knock sensor we thought it would be a good idea to check how his is looking. Well to our suprise there was absolutley no black goo or anything in his knock sensor. It was completly gone, jus a nut with a wire going into it screwed into the block. The weird thing is how come his car didnt throw any CE lights? I logged it and it was pulling timing like a mofo...good to say we installed a new knock sensor and everything seems fine now, but im curious to know how come his engine didnt throw a code when his sensor was 100X's worse then mine?

 

[ASHICK]

just because a part may look like crap it may still be functioning must light are usally caused by a total failure ie electrical or picked up via another sensor monitoring its performance.


later
Ashick

 

[Quasimondo]

Knock sensor code won't be thrown unless the ECU can't detect the knock sensor. Even if the black goo is gone, if the ECU can see it, then it won't throw the code.

 

[firebirdvert305]

yea but when we logged it...he was getting 43 counts of knock accelerating/decelerating no matter what he did. Im sure the knock sensor contribuited to that somewhat. His lifters have no ticks. After we installed the new KS on his car there was a world of a difference.

 

[Quasimondo]

The black goo helps filter out the sound of spark knock from the regular mechanical noises of the engine. With the black goo gone, there was no way to filter it out so everything the sensor picked up was considered knock. The ECU is not going to know that the goo is gone, it's just going to see that it's pinging like you've given it a batch of the finest 87 octane money can buy and yank the timing.

The only way to get a CEL for the knock sensor is to disconnect it from the wiring harness.

 

[firebirdvert305]

That possible then if my car threw a check engine light with the connector still connected with everything intact