Tons of knock retard! - Third Generation F-Body Message Boards

Marc 85Z28 · 03-08-2004, 04:30 PM

My car has been running slower and slower over the last few weeks, and the exhaust note is changing too much. After checking the timing, and getting all sorts of strange fluctuating readings, I decided to put it on my shops Snap-On scanner. Turns out I'm getting a good bit of knock retard. There is no audible detonation and the plugs are reading fine. I'm still running the original 1985 LG4 piece, and now have headers. I've heard that these knock sensors can be quite sensitive and are known for false knock conditions. I did a search and apparently you can't just disconnect the sensor. You must provide a resistance signal to the ECM for the ESC to work properly. My question is this: What resistance do I need for my year? Or could I just check the resistance of the sensor with the engine off, even if it may be faulty?

dankhound · 03-09-2004, 03:41 PM

If its just a one wire ks you wont need a resistor because that type produces electricity. If its a two wire you would need a resistor because the cpu needs to see resistance there or else it will think theres a problem.

AM Racer · 03-09-2004, 09:19 PM

Generally you can ground out the wire from the sensor to check. The wire can be left disconnected, but not recommended. It can work as a sort of antenna picking up stray signals and transfer to the computer.