I have a 92 blazer 4.3l "w" that constantly sets a code 43. Both knock sensors test good at 8.2K ohms. The voltage to the knock sensor is what I am after. Mine both read 3.27v but my Haynes manual says 8-10v, other threads I have read say 5v. One thread I found, I don't remember where now, said that a code 43 would set if the ECM reads above 3.5v or below 1.5v for more than 4 seconds.

I have checked the plugs as well and they are in good shape. This is the last piece of the puzzle for me. I just got done replacing the CPI and hoses, my hoses had worn down on the CPI injector lines as everything was routed wrong.

The truck runs real good when cold but runs like dogsnot when warm.

I am leaning towards and intermittent short, which I have been unable to find so far, in the knock sensor wiring or a bad ECM.

 

i was getting this code and could not figure out why so i put a new pigtail on and have not seen this code since then. mine was the one in the drivers side of the block that had a bad connection in it...hope this helps a little