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Old 11-24-2009, 01:43 PM   #1
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Default Knock sensor/light

Looking around for info on knock lights. I'm on a couple different forums now reading what others have done and trying to compose a low priced knock sensor setup. I thought I remembered seeing something on the DIYautotune website that had a way to hook the knock sensor up to the MSPNP, but I didn't see it on there just now. Now I'm looking at the turboXS knock light.

Anyone on here want to suggest anything? I feel like this is a most necessary purchase along with a EGT gauge.
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Old 11-24-2009, 01:51 PM   #2
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The knock-lite seems to work well from what I have read. It is also one of the few affordable systems that is adaptive to engine noise at different rpm which helps to avoid false knock. Unfortunately it wouldn't be a plug and play affair due to its output being digital, although according to one of the engineers over at turboxs it has been made to work with non turboxs aftermarket ECUs...Sounds like a problem for the great Joe Perez.

There is also knocksenseMS, however to me it seems like a mixed bag. For every guy that says it works like a charm, there is another guy who says that it is a paperweight. Though to be fair, it sounds like adding an additional pot into the output helps.
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Old 11-24-2009, 01:57 PM   #3
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Quote:
Originally Posted by Jeff_Ciesielski View Post
The knock-lite seems to work well from what I have read. It is also one of the few affordable systems that is adaptive to engine noise at different rpm which helps to avoid false knock. Unfortunately it wouldn't be a plug and play affair due to its output being digital, although according to one of the engineers over at turboxs it has been made to work with non turboxs aftermarket ECUs...Sounds like a problem for the great Joe Perez. There is knocksenseMS, however to me it seems like a mixed bag. For every guy that says it works like a charm, there is another guy who says that it is a paperweight. Though to be fair, it sounds like adding an additional pot into the output helps.
I just found the page on knocksenseMS. That's the one I was thinking of.

Engine knock detection and indication for all vehicles

I just read the installation manual for the turboXS light and it seems pretty advanced. Idle check, mid rev check, and a high rev check. Then you can fine tune with a sensitivity control, levels 1-10. Seems like the way to go I guess, not bad for $100 bucks.



http://www.turboxs.com/uploaded_images/558.pdf

Any recommendations on a good knock sensor? Just a Bosch one from whatever kind of car? Or are there better ones out there to look for?
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Old 11-24-2009, 02:07 PM   #4
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IIRC most knock sensors are just a piezo mic, so it wont really matter. I'm pretty sure any Bosch unit will have the same frequency response and its up to the controller/ECU to set the filter levels.

EDIT: I've really been thinking hard about about getting a knock-lite and scoping/probing the output. Apparently it flashes different colors for different intensities of knock, so it isn't unreasonable to think that a cheap circuit could be built to read that signal, and output something suitable for the MS's knock input. Thinking about it, if it uses the standard logic signal (which I believe is +5VDC), it might not need to be altered at all, but it might look weird. ( anyone feel free to correct my non EE newbness )
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Old 11-24-2009, 02:24 PM   #5
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subscribed to this thread, been researching the same thing for a bit now and was also wondering what type of knock sensor to go with, as in bosch etc etc...

where did you find this knock light at for $100 vash?
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Old 11-24-2009, 02:35 PM   #6
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Originally Posted by NAshowdown95 View Post
subscribed to this thread, been researching the same thing for a bit now and was also wondering what type of knock sensor to go with, as in bosch etc etc...

where did you find this knock light at for $100 vash?
On ebay for $96.75 + $7 shipping, but with the 8% paypal cashback it comes out to be $95.45.

TurboXS Universal KnockLite Knock Detection Shift Light:eBay Motors (item 110460418853 end time Dec-21-09 03:34:32 PST)

Use bing.com searching for SONY to get the 8% cashback link to ebay.
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Old 11-24-2009, 02:56 PM   #7
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I had a TXS knock lite back when I was running my FM II/Motec combo. It worked OK but I could never get it to integrate with my Motec. While there is a learning procedure with revving the motor so it can pickup engine noise vs knock to set sensitivity, the only real way to do that is to set it up while on the dyno and compare the knock to torque dips on the dyno chart. It did light up when my BEGI DP kept hitting the k-member so I know it worked.

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Old 11-24-2009, 03:18 PM   #8
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It's not exactly a knock light, but I use this and it has an audible warning and LED warning light.
KS-3 Knock Detection and Engine Tuning Systems
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Old 11-24-2009, 03:35 PM   #9
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It's not exactly a knock light, but I use this and it has an audible warning and LED warning light.
KS-3 Knock Detection and Engine Tuning Systems
For some reason, I seem to recall Andre at Pina Motorsports telling me about this a while ago. He spoke highly of it. But $325 bucks plus shipping from across the pond...
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Old 11-24-2009, 04:12 PM   #10
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Quote:
Originally Posted by Jeff_Ciesielski View Post
For some reason, I seem to recall Andre at Pina Motorsports telling me about this a while ago. He spoke highly of it. But $325 bucks plus shipping from across the pond...
They actually have a couple vendors in the US now that stock and carry it so you dont have to deal with shipping and import taxes.

$325 may seem like a lot but my pistons, rods, cylinder head, and labor are worth a lot more than that.
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Old 11-24-2009, 04:12 PM   #11
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Quote:
Originally Posted by Jeff_Ciesielski View Post
IIRC most knock sensors are just a piezo mic, so it wont really matter. I'm pretty sure any Bosch unit will have the same frequency response and its up to the controller/ECU to set the filter levels.
Indeed. Much like when measuring wideband AFR, the knock sensor itself is a fairly trivial part of the equation. A quality signal conditioner is what makes the difference.

Unfortunately, the Megasquirt doesn't have one.

The MS's provision for knock sensing is fairly primitive. It accepts a logic-level signal to tell it whether there is knock or no knock. So we need a device outboard of the MS to take in the signal from the sensor, process it, and toggle an output.

There are a couple of ways to do this. The simplest is just a bandpass filter tuned to the predicted knock frequency of the engine, which rejects all sounds that are outside the range of the knock frequency, and passes all sounds within it. That's what the KnockSenseMS (which is what I have) tries to do.

It's not very good at it.

It could be worse, of course. If the proceeds of its sale were being used to fund terrorism or support the poaching of endangered species in South America, that would be worse. But the problem is that engines are noisy as hell. They generate all kinds of broad-spectrum sound, some of which falls into the same range as knock. So with KS, all you can do is set the detection threshold to be somewhat above the worst-case ambient noise of the engine, and hope that the knock is louder than that.

It would appear that the Phormula box is doing essentially the same thing, albeit with a much friendlier tuning interface. And the KS-4 is likely MS-compatible.


Another approach would be to dynamically pre-scale the input signal to a variable that roughly tracks the amplitude of ambient noise being produced by the engine. The TurboXS box does this by taking in an RPM signal, and using this to adjust the relative sensitivity of the device. Personally, I question whether RPM alone is sufficient (I would think that noise intensity would vary with load) however I can't say I've done any first-hand analysis on this. It's a nice idea, though.


Within the realm of the OEM (on current-generation designs, at least), they're obviously getting a bit fancier, using some DSP horsepower to actually analyze the signal in some detail, looking for waveforms which differentiate knock from noise. I'm not aware of any third-party solution which operates at this level, and frankly, it's likely beyond my abilities to attempt.
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Old 11-24-2009, 04:28 PM   #12
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Quote:
Originally Posted by Jeff_Ciesielski View Post
For some reason, I seem to recall Andre at Pina Motorsports telling me about this a while ago. He spoke highly of it.
He's the one that got me hooked on it as well. We used another one of their products while tuning my car on the dyno and it worked great. I'll have this particular item in the car by next summer.
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Old 11-25-2009, 02:53 PM   #13
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The Phormula products look great - I just went over their entire website and it looks like a top notch solution.
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Old 11-25-2009, 08:36 PM   #14
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Been using the TurboXS Knocklite for a few years now, can't recommend it highly enough.

Picks up the slightest of det through the entire rev range.

It's advisable to set it up with a set of det cans, but once it's running it's a fantastic piece of kit with not 1 false knock in the 4 years odd i've been using it.

To set it up you simply free rev the motor to tickover, mid point, 7000rpm.

It then uses the noise at those rpm points as a datum point.



Great kit.


Cheers
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Old 11-25-2009, 09:09 PM   #15
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Originally Posted by eunos1800 View Post
To set it up you simply free rev the motor to tickover, mid point, 7000rpm.

It then uses the noise at those rpm points as a datum point.

Great kit.
And why I'd still tend to lean towards it, rather than the one with the phunny name, despite the fact that the latter costs more and looks cooler. All evidence suggests that KS-3/4 boxes are using a static reference level, whereas the TurboXS unit (at least in theory) has a variable reference level.

One of these days I need to get off my *** and scope my knock sensor under both varying RPM and varying load, to see what really matters most...
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Old 11-25-2009, 09:35 PM   #16
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Gotta say i was impressed to bollox with the Phormula units and came to within a gnats bollock of buying one.

A person who's opinion i tend to trust tried one though and said he could not set it up to work correctly on a MX5.

Our motors tend to be very noisy which is the problem with most knock detection devices.
Seems that the Phormula units are unable to differentiate between noise and det at higher rpms.

So i stuck with the knocklite.


As i say though if you do fit one, i would strongly advise checking it's operation with some det cans first before trusting it.


Cheers
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Old 11-25-2009, 10:53 PM   #17
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Quote:
Originally Posted by eunos1800 View Post
Been using the TurboXS Knocklite for a few years now, can't recommend it highly enough.

Picks up the slightest of det through the entire rev range.

It's advisable to set it up with a set of det cans, but once it's running it's a fantastic piece of kit with not 1 false knock in the 4 years odd i've been using it.

To set it up you simply free rev the motor to tickover, mid point, 7000rpm.

It then uses the noise at those rpm points as a datum point.



Great kit.


Cheers
Mark
Could you tell us about some situations when the Knocklite detected knock and you found there to be a valid problem with your setup/tune/engine/car? Has it saved your motor from damage before?

Did you calibrate it on the dyno by advancing timing until it started to knock?
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Old 11-25-2009, 11:37 PM   #18
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I've a few problems over the years with det/knock.

Couple of bad tanks of fuel (Knocklite detected them)
When first tuning my car i had some det at the beginning of summer (knocklite detected it)
Last year my fuel pump was on it's way out (knocklite detected it)

Plus i'm always messing about with my tune and every time i've gone to far with the timing it's detected the faintest hint of det.


I have had a blown motor, but that's 100% the **** of a drivers fault (me) rather than the knocklites.

It was flashing blue murder, but of course i knew best and ignored it and popped me motor.


That's really the only downside of the KL, it's not active knock control just a knock warning system.
But then for the price it's still great VFM.

It's been tested several times wit det cans and it's capable of picking up the slightest bit of knock.
Obviously det cans are better for tuning, but as a saftey measure that's constantly running it's a great device.

It also has a built in gear change indicator and the light is very bright and noticeable even with the top down in summer during the day.

It comes with velcro tape, so you just stick it on the top of your steering cover, wire it and your good to go.


There is 1 output that's used for Subaru ECU's, i believe it's a knock output signal that feeds into the ECU but have not been able able to find anymore info on the type of signal it is.

So it's possible you MS guys may be able to utilise this output as a knock input after some work.

My cars never visited a Dyno, so all the setup was done with road tuning and det cans.


Cheers
Mark
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Old 11-25-2009, 11:42 PM   #19
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Bit more info.

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Couple of pics of mine installed.

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Cheers
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Old 11-26-2009, 12:51 AM   #20
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Thanks for the [email protected] I think I'll pick one up. It's much chezeaper than the phormula. My Hydra's supposed to retard but I'm not sure it really reacts rapidly enough to prevent damage. The last time I dynoed I was running out of fuel above 6500 RPM because of my fuel pump. The hydra did hard retard then, but I had never noticed anything on the street-- probably since I'm only above that RPM for a couple tenths of a second.
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