Been searching like crazy but cant seem to find an answer. My brother has a 2001 blazer, blew the motor, and paid some guy to put in a used one out of a 2000. The check engine light came on but it seemed to run fine so he didn't care but now that the inspection is due he needs the light off and it has become my problem. The only code is for the knock sensor so I checked and it's not even hooked up because obviously the harness doesn't match the sensor that came with the 2000 engine and the "mechanic" never changed it over. I've read a lot of posts telling how to retap the hole to retrofit the sensor, but I can't find any solutions on how to switch over while the engine is in the truck. Can anyone point me in the right direction?

 

So just to follow up in case anyone else has this problem, I bought the 2001 knock sensor, took the back passenger side bolt out of the intake manifold, replaced it with a longer bolt and mounted the sensor there. The bolt was the right diameter for the hole in the sensor and the clip on the harness reached with no modifications. I'm sure there's going to be people telling me I'm a moron and that I can't do that, but it's been 5 days with no check engine light and the truck is running fine. Even seemed to correct the inconsistent shifting if that's even possible.

 

Are you using one of the bolts holding the upper plastic plenum or the lower intake manfold? If its the upper plastic plenum, the problem with the new location you have chosen is that it will not accurately detect pre-detonation due to the damping effects of the plastic intake manifold. Your engine will likely run ok when there is no pre-detonation, but you may run into potentially harmful pre-detonation if the engine is pushed hard. Your call.

The conversion process doesn't really work backwards such as you require. You can't make the hole smaller. What you could do is take a common hex head pipe plug that fits the hole in the block & drill/tap it to the thread needed for the knock sensor. Thread it into the NPT hole in the engine block, then attach the newer style knock sensor and be back to proper. If the pipe plug didn't give enough of a surface to mount to, a machine shop could make the necessary piece relatively easily.

 

No, I used the back left bolt on the lower manifold. I figured it's a metal bolt threaded into the iron block only inches away from the original mounting location, so I was assuming that any knock that would be detectable at one location would also be so at the other. I have since given the truck back to my brother and he says still no CEL, so I guess a rigged sensor is better than none at all haha. Thanks for the reply, I wasn't getting any feedback from anyone else..

 

No, I used the back left bolt on the lower manifold. I figured it's a metal bolt threaded into the iron block only inches away from the original mounting location, so I was assuming that any knock that would be detectable at one location would also be so at the other. I have since given the truck back to my brother and he says still no CEL, so I guess a rigged sensor is better than none at all haha. Thanks for the reply, I wasn't getting any feedback from anyone else..




So how is the truck now did it pass the inspection? Did the CEL is back on because of the knock sensor? I'm having the exactly same issue here...