Adding Knock sensor
 

Has anyone been able to add a kock sensor?

ECU's do support it but most Miata's never came with one. Would there be a good place to mount one? Has anyone been able to get one working?

Can't see much solid guides online for this.

As to why? why not? Another reason to have that check engine light shine in the nigth

usually the reason of why not is because to be able to tune the KnockSensor, you need to get your engine to KNOCK,,,,,so people rather not do that.

NB 1.8 VVT has a resonant knock sensor as standard. Its below the inlet manifold between pots 2 and 3 as expected. I added a bosch motorsport non-resonant/broadband knock sensor when my car was NA. I proceeded to det the hell out of it at low load while NA to tune in on the frequency on the Haltech.

I now run those settings since turboing it and they are very accurate. On the odd time I have been greedy with timing or leaned it out too far in transient areas I have had the ecu instantly detect and pull timing - it works really nice and effectively. I reckon it saved my engine on a track day where I put bad fuel in and still pushed on for the whole day like and idiot.

The standard knock sensor position is hard to get to without taking the inlet manifold off. For ease I first removed an engine mount bolt then welded another bolt onto it back to back to create a stud. This gave me a stud to connect the bosch knock sensor to and hold on with a nut while still being an effective engine mount bolt to the block. This position works a charm and appears less noisy than the standard position as its further from the head and injectors.

You need to make a crossover stud for the standard knock sensor hole if you use it as its too large for the bosch sensor. Some people drill the bosch sensor out slightly but I wasn't willing to potentially compromise the sensor given its task. I think the block is M10 and the sensor has an M8 hole or its M12/M10 - can't remember exactly.

I believe my engine would probably already be dead if I didn't have the knock sensor - its helped me learn along the way as its all self-learn, self mapped. Transient knock events are especially hard to hear and its amazing how the ecu picks it up clearly.

@Mr_Plow:
Do you have a PN by any chance for the Bosch sensor? I think this is the route I want to go, trying to induce knock at low load cruising dialing it in.

Would you post a screenshot from your settings for the knock sensor? Just as a rough guide line, can't be that much different, when mounted in the same location. Maybe even how you wired it to your ecu (haltech I believe?) for the n00bs.

This is a topic a lot of people stuggle at

I'll be able to do it after work. I plan to do a post on my whole Haltech map explaining each section of it which may help people - it may also create constructive criticism that I can learn from.

There is one maybe critical thing I remember, when I change knock sensors on M5X engine on BMW's: The torque is somewhat critical (~15ft lbs IIRC) for this type of sensor. Did you use a torque wrench or just tightened it down?

I hand tightened it and have lock tight on it so its not at uber torque. Same type of sensor on my det cans - again just hand tight - no torque wrench - both work a treat and tests backed each other up when det was induced. I'd have used a torque setting if I'd known it at the time.

The sensor I use is one of these:
https://www.bosch-motorsport.com/con...118019851.html

I found the center knock frequency of 12,323Hz works well on my engine on the Haltech. I found this by initiating det at low load when the car was NA. I backed this up with det cans ensuring it was actual det I focused on.

My Knock threshold table was set up from driving around on a super safe map for a while. I used Megalog Viewer HD to create a histogram with a ton of data points for confidence. I set the threshold slightly above the histogram.

https://cimg7.ibsrv.net/gimg/www.mia...d0f6bf9d1d.png

I then verified the threshold with det cans again by inducing light knock. I now trust the system following quite a bit of checking with det cans. The Haltech is nice because it instantly pulls timing at a rate determined by the user and can also restore if you want over time with no further occurrences. You can quickly look at the long term trim table to see where any issues may be occurring.

Thank you very much!

I have one set up in mine.

You will want something like this to fit the Bosch sensor to the BP block in the original knock sensor position:

https://www.ebay.co.uk/itm/144450035...SABEgLtjfD_BwE

https://www.efisolutions.com.au/knoc...stud-m12-to-m8

I never saw these at the time. I used a OEM Toyota stud which goes from M12 to M10. I hand filed down the M10 thread then re-threaded it to M8 for the Bosch sensor. Works a treat and was cheap.

is there a spot for knock sensor on NA1.8 BP?

Yes. Directly above the oil pressure sensor there is a 10mm fine tapped hole.

if someone is looking to buy knock sensor I recommend this one ECUMaster Knock Sensor

it comes with a connector and stud.

https://cimg5.ibsrv.net/gimg/www.mia...25e9c52ea3.png
I used an NC knock sensor and made a stud from a spare bolt.

Nice! why is your oil sender mounted 90 degree, does it give you more clearance to install knock sensor or to remove the oil filter?

my main worry is that the NC knock sensor might be too noisy, assuming its ground is not shielded and I'm not sure if that sensor is wideband or frequency specific.

but I mean if it works it works.

the most important part when wiring knock sensor is to use shielded wires and to ground the shield at the ecu ground signal.

do you have a datalog of a real knock against the threshold, this should give us an idea if it's too noisy or not.

its mounted at a 90 for clearance and I built a bracket to support it, I was worried about vibrations breaking it from the vvt mount.
I believe the NC sensor is a wideband type, i used it on recommendation from my ecu maker
I regret not using shielded wire, but it didn't seem that big a deal when I asked about it.
car isnt running yet to know how it works

FYI you can use an M8-1.25 helicoil in the hole tapped in the block to mount a Bosch sensor. doesn't require drilling or retapping, just thread the helicoil into the m10-1.25 hole under the intake manifold.

I'm still using the Flyin Miata knock sensor from the Link ECU days. FM supplied a bolt that replaced a motor mount bolt, that had the thread for the bosch sensor. Currently i'm sandwiching an electronic det can (copied the diy from this site) between the factory knock sensor location and the FM bolt, with the bosch sensor screwed on top (not in picture).

I tune the bosch sensor by reving the engine in neutral and getting the background signal. Then anything above this signal is knock and it pulls timing proportional to the signal strength, IIRC.

https://cimg1.ibsrv.net/gimg/www.mia...c301a0bbe8.jpg
https://cimg2.ibsrv.net/gimg/www.mia...b319d21d6e.jpg