How far out to lunch does a Knock sensor have to be, before it causes the ECM to throw a code? I'm positive that around 40 mph in O/D, when the RPM is around 1000, it knocks. and thats with 89 octane. Pretty much when the engine is under any real load either on level ground or going up a hill especially, with low RPMS. It's a ticking sound like someing is tapping on something. Now I have checked my Timing and it is where it should be for being a stock engine. So I am a little confused.. oh, and 92 octane doesn't make much of a difference either (strange).. Has anyone else had the same problem?

 

F.E. / B.C.,

Your ECM is one sneaky sunnamich. It will try to advance timing as much as it can under most conditions up to the point where it detects a detonation event. Then it will step back to a point where there is none. It relies on a working ESC and KS to get that information.

The KS doesn't do much more than act as a microphone for the ESC. The ESC exchanges that "sound" with the ECM to manage the timing.

Don't be so quick to condemn the knock sensor, however. Remember that before Ed Cole figured out that the holes in the sides of the block were mountings for knock sensors, they were simply used as drains for the cooling system. That being the case, they were appropriately placed in the lowest part of the cooling jackets. As a result, that part of the cooling system is frequently the first to accumulate sludge and deposits. The rust, sludge, and gunk will act as a silencer or muffler for the KS. Therefore, the KS itself migtht be just fine, but it cannot "hear" through the layer of junk to detect the detonations.

Have you flushed/drained the cooling system lately? That little chill in the air means it might be time to at least look at the coolant.

 

Yes the system has recently had a complete cooling flush. So should I then perhaps drain the block again and pull out the KS to see how clean it really is is there? I'll be storing the car for a much longer period this time, so I will be doing lots to it..

 

It wouldn't hurt to drain the system (catch the coolant for reuse if you like), pull the KS, and see how clean that area truly is. If that side is really full, you might want to remove the drain plug on the left side, but be warned that they can be a real chore to get loose.