I was trying to change my knock sensor and it broke just left the threads. Tried vise grips to get it out but that didn't work. so I extended the wire and ran the sensor to the top and hooked it up then wrapped a wire around the threaded part and then hooked it to chassis ground. Now when I start it my SES light comes on. Why didn't this fool the computer idd I do something wrong?

 

If I understand the only thing left of the sensor is the threaded portion which is still screwed into the block? If so, then you are missing the most important part of the sensor. It is basically a "piza" microphone which listens for knock.
Your easiest solution is to just drill out the stump stuck in the block and get yourself a new sensor.

 

i have a new sensor that i hooked up

 

The PCM looks for a voltage in th range of 1.5-3.5V with the sensor connected. Perhaps when you "wrapped a wire around the threaded part" you didn't get a clean connecton, and the resistance is too high, causing the circuit to run a voltage outside of spec.

And, since you were apparently changing the sensor for a reason, was the SES light on before you tried changing it?

Did you consider putting the new knock sensor in the drain hole on the drivers side of the engine? Or drilling the old sensor and removing it with an EZ-out?

 

No I had no SES light before. Guess I need to apply to the "If it ain't broke, don't fix it" rule more lol. I seen the drain hole but looked like the motor mount would be in the way. My drill is too big to fit up in there.

 

Sorry for the long delay, but my computer went down, and I've been busy the last couple days. I wrote the quote above that morning and finally got the SOB out that night. I took the driver side motor mount out and jacked that side up to angle the passenger side down some. I borrowed a smaller drill from my uncle. There still wouldn't enough room and I had to drill through the threaded part at an angle. I went far as I could til it looked like I would hit the block and then took a small bit and used my dremel to go through. After the coolant drained, I took an EZ out the first one quit catching and just started slipping. So then I got a bigger EZ out and when it started catching, I took a propane torch and heated around threaded part. And then she finally came out.

And Injuneer, after putting my new sensor in my SES light still came on. But when I put my headers on I lengthend the knock sensor wire, pcm ground, and a starter wire so I could reroute them. Apparently while I was working on the knock sensor, I pulled down on the wires and the quick connects I had on them pulled loose. This time I soldered them together. Do you think if I would have fixed the wires that it would have worked when I ran the KS to the top? sorry for the long post.

 

If you had +5V from the PCM to the unconnected harness connector for the KS, and if you had a good connection from the KS to the ground, it should have worked. You could have accomplished the same thing with a 3.9-4.5Kohm resistor.