Testing Knock Sensor

[Jonasterg]

Am I testing my knock sensor correctly? I believe the knock sensor is circled in red on the attached picture. To test it, I turned on the car, blocked the wheels, and put it in neutral. Then I brought it up to ~1500 RPM and tapped on the block with a long ratchet extension (around the area of the red/yellow circle).



No stumble, ScanMaster didn't show any KR. I took the car out with my uncle a week ago - thought I heard some knock at WOT in 2nd gear, but the ScanMaster didn't register anything and O2s looked good (780 I think). Afterward my uncle said he thought he heard pinging too.

Wondering if my sensor is dead, or if the wiring got buggered up somehow.

 

[RmvBfrFlght]

That is the correct test procedure for the knock sensor. Although can leave the trans in park. Note that the engine needs to be up to temperature before the ECM will retard the timing. Actually, looking at the PromData SS, engine needs to be above 46* F.

The filter is on the passenger side among the fuel pump & A/C relays. Flat square plastic block. Can unplug it and start the engine, should get constant knock counts and the associated retard. If not then it is likely that the ECM is bad.

Can measure the sensor resistance. From center pin to body should be about 100 K ohms. If it is open or shorted then it is definitely bad.

RemoveBeforeFlight

 

[YAKO]

I was told by john spina to tap on the knock sensor it self ..i did the same as you and could not get a reading on my scanmaster but when i tapped on the KS i got 3 to 5 degrees of knock indicating all was well

 

[Jonasterg]

Good to know. I'll test it by taping the sensor directly. If that doesn't work, a buddy said I can borrow his temporarily. That way I can see if it's the sensor or the wiring.

Thanks.