OneSilverS2k

Lets see I have taken more automotive classes then you would like to know. Also the S2000 is my 27trh car. I have had 20 of those 27 cars all turbo and I do use 87 on all for daily use i.e, not revving past 5.5K. I have also monteriered knock on cars to test this.

kaissi

No doubt, but you didn't answer me... you supported my question

If the shape of the piston is the one that affects the knock sound then that is why F20 and F22 uses the same knock sensor and do not use the CIVIC or ACCORD knock sensor...

But is it the case?!!

OneSilverS2k

I don't know that would be a good question.. also if it has nothing to do with the shape, I wonder what a civic piston looks like? The civic being a 2.0 I forget the stroke, I can look at up, I just really think I am coming on to something with this knock sensor. When i get my AEM EMS I may run some tests before turbocharging the car and see what the knock levels are.

kaissi

Then can you explain how the same sensor works for AP1 and AP2 ?

Why is there a green and gray color.. could it be a sensitivity index?
i.e Accord MY2000 and S2000 has same knock sensor
both are green ... same size...same shape... I bet if you give them to a dealer, he won't be able to tell which is which

s2k16803

sorry to bring up this thread but did anyone ever figure out if the civic si knock sensor is good to go?

OneSilverS2k

Do what you want I guess. Everyone seems to hate on the idea haha. I ran mine for 6000 miles and at the hardest condition possible on the Dragon and back home. No issues. If something were to happen I would guess it would be around those parameters.

TRD_Celica

any updates? Engine go kaboom?

Billman250

I'd imagine when any knock sensor is designed, the engine it was designed for was made to produce a spark-knock under controlled conditions. I would also believe the knock sensor was designed to "listen" for that specific frequency, and deem it as spark-knock (pre-ignition).

I would imagine many factors could affect THAT PARTICULAR frequency. Position, engine wall thickness, amount of accessories, the list is endless. Take an exhaust on a running car. Hold it with your hands while running, you change its tune. I'd imagine therte are a range of frequencies, and sometimes they may repeat on different model cars. But each is designed to hear the knock on the engine it was designed for.

I will safely conclude that the frequency of spark-knock on the s2k is different than the civic. I think if you use the civic sensor, the ECU will just not "hear" the spark knock. In addition, other frequencies could set it off. will it keep your CEL off? Of course. Will it protect you engine from spark-knock? I highly doubt it.

does anyone else agree with this?

For me and my customers, s2k knock sensor only. There is no way I would recommend anything else. Not for nothing, it's not a wear item. People break it because they are careless, and it positioned just right, and fragile. If you are looking for a cheaper knock sensor, YOU or your "mechanic" broke it or you bought the car that way.

cloud9bill

Any updates on this issue?

T-Smac

Knock sensors are specifically tuned to the engine knock frequency (somewhere between 5 and 10kHz), depending on the engine design. Everything is a factor here. Any abnormal combustion that occurs is seen by the knock sensor and the ecu retards ignition timing.

Get a scan tool, your car, and another S with the OEM knock sensor together and do this: Start the engine and go to the knock sensor monitor on the scan tool / advanced code reader w/e you have that can see data stream. Simulate a knock by tapping on the block or head with a soft faced mallet or very small ball peen hammer. The ecu should see a knock occurring. Now see if it shows on both cars, and also if the same amount of force is required to see that knock (dont beat the crap out of your engine here.) and note whether timing was retarded or not. Any inconsistency shows that you are putting your engine in danger.

Also, if you can get your hands on an O-scope (oscilloscope), hook that up to the sensor and watch both OEM and the SI sensors during the simulated knocking.

Point is: The engine design is different between the S and Civic Si, and thus the knock sensors WERE designed differently. Not maybe, not almost, WERE. Of course they will use the same thread pitch and size, because that will save them money. However, the color is there to say "HEY, THIS IS NOT THE SAME BRO". What has changed is the type of crystal inside the sensor that created voltage when pressure or vibration is applied to it.

I'm not saying you can't make it another 100k miles with no problems. But any slight problem that could cause spark knock (lean air/fuel, vacuum leak, carbon buildup on the piston) can lead to catastrophic failure of the engine. You get a dirty injector and your engine might blow! A crack in a vacuum line could be the death of your engine. It doesn't seem logical to me to assume that you will never have any problem that would cause a slight knock.

A healthy engine can very well spark knock, and without being able to detect said knock, engine failure is likely.