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Knock signal weak on knock link (SR20DET)


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The factory engine knock sensor is connected solely to the knock link. With the sensitivity setting on the knock link turned to fully clockwise positiion which is the most sensitive setting. However only the first led on the knock link light up with engine rpm rev up to 7000 under heavy load. This insignificant in knock sensitivity is causing problem to detect engine knock effectively. I am running short of ideas on the possible cause of this fault. I tried to reconnect the whole knock link wirings to an additional knock sensor mounted on the cylinder head. The result improved slightly to two led light up under the above testing condition. My question is, are there any possible method to boost up the knock sensor signal to knock link ? The possibility of faulty knock sensor or faulty knock link seems low. It feels to me that unexpected signal reduction has occured within the wirings. Since the current wiring method untilize the factory knock sensor wire, running from the knock sensor to a connector on top of the intake manifold. The knock link wiring are joined from this conector and run through the engine fire wall. As i have mentioned above, to verify this problem i tried to mount an additional knock sensor and secured on the cylinder head and reconnect all the wirings using new wires but the results wasn't significant enough to identify the problem. This vehicle is running a G4 plugin, without the correct engine knock information, other required work connot be continue at this point. If anybody can provide some suggestion on this problem would be very appreciated. Thanks.

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Mounting your second sensor to the cylinder head is not ideal, as the signal tends to be a little quieter.  For you to perform a fool proof test, I would mount a known good working sensor with new wiring and confirmed continuity.  But mount this in the factory sensor location and only have that one.

The possibility of the KnockBlock being faulty is there but rare as you say, it can be considered legitimately if you have tried everything else though.  If you would like you could send it in to Link to be tested.  There will be a small charge for this, but not horendous.  Email [email protected] for a quote.

If the unit has been sitting around for a long period of time, It may be a prudent idea to check any plugs and pins in the mix.  Looking for corrosion or bad connections (failed crimps or solder joints).  The switch that shows the frequencies 6kHz, 7.5kHz, and 9kHz, for the SR I would suggest it to be in it's first position of 6kHz if it is not there already.

Let us know how you get on.



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I belive that pcb is using the old knock link which only has a sensitivity adjustment

reving the engine to 7000rpm with no load on will generally not produce the noise level that the knock link is looking for  remember it is for knock not valve train clatter

i would not rely on a knock link for tuning  use a dyno and a headphone system to tune it



[email protected]


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