My understanding is that the function of the knock sensor is to
detect engine knocking, and communicate to "computer" which
in turn retards the timing.
What I don't understand is the following:

- If the engine knocks loudly in the 1st place, could
this be an indication of faulty knock sensor

- Can one assume that the louder the engine knocking,
the stronger the degree of retardation

- Does it retard timing / ignition for all cylinders simultaneously,
or just particular one

- How does one test knock sensor for functionality

"- Can one assume that the louder the engine knocking,
the stronger the degree of retardation?"

Less retardation=more knock. Retarding the timing effectively reduces the compression ratio as the fuel/air mixture is burned before maximum compression is reached.
Check function of knock sensor and also for carbon in the engine (pull the plugs and check them). Verify engine is timed correctly, if you have timed it with your original harmonic balancer in place it may be off by quite a bit, as they tend to slide around when aged.

Shifted
--
'87 745t 217,000; '93 Toyota MkII; '73 Suzuki Jimny (Brute) LJ20 360cc

On your model it retards all cylinders at once. Without cracking the manual on it I recall it was a 4 degree retard until knocking subsides and then re-advances at 1 degree per engine revolution until knock and then back 4 and so forth and so on. Total retard I recall being either 16 or 20 degrees. It was a real basic circuit back in the days of your car. As it evolved it got to where it would retard individual cylinders and had a much finer control, none of this 4 steps back and one step forward stuff.

If an engine knocks loudly it may or may not be an indicator. I would simply test it, on those old systems you could put a timing light on it and hit the block with a hammer and actually see the timing retard.

Yes, I would have to assume that the louder the knock the more drastic the timing retard.


Mark

The sensor is a piezoelectric device that senses knocking and signals the ECU, which alters timing accordingly. It should stop all knocking except that which is so severe it cannot be eliminated by altering timing. See the FAQ for testing procedures.