Adding a knock sensor to MS??
 

Hey have any of you guys seen this webstie http://www.viatrack.ca/
they sell the KnockSinceMS that appears to make it VERY easy to add an knock sensor to your MS. It is about 90 dollars with sensor which really doesnt sound too bad.
What do you guys think? I feel that a KS would make tuneing a little more safe. Having the MS retard timeing when it hears a knock and seeing the led blink will let you know to take your foot off the gas and retune :gay:

nobody?

I did a little homework on where to mount the Knock sensor
http://img211.imageshack.us/img211/5981/ks5tk.jpg from FM's link manual
it looks like it uses the same sensor as the knocksence. cool

If I were running a turbo I would certainly use a knock sensor. This looks like the way to go. What pin on the DB37 is needed to do it?

It looks like pin 27 and you make a jumper from x12 to jp1 pin #5
Diagram is here http://www.viatrack.ca/KnockMS/KNOCKMS_SUP.JPG

i ran a ks with my link and it was THE piece that really puts your mind at ease. if i could run one with a ms, it would definitely help.

Great work mate!!!

Let us know how it goes.

I will when I get around to acutally GETTING the MS haha :gay: . I think I am going to save up and buy a beater to drive first so I can take my time on the miata for now on. I hate stressin' about finishing something before monday.

This will be something that I do before I put the turbo on the car! Nice find and cheap too... does anyone know what that source is for the knock sensor? (as in what car did it come on originally?)

Thanks,
Chris

It's a Bosch knock sensor I have no idea what car the guy gets the from, so you should shoot him an email. It looks like its the same one that FM uses so I would try to get that handly custom bolt they have.

I've started to build the knock sensor controller shown on the MSnS-extra page:
http://megasquirt.sourceforge.net/extra/knock.html

Here it is in VERY early stages: :bigtu:

http://static.flickr.com/45/114592865_1367ccd113.jpg

I'll keep you posted with how it goes!

oh awesome man! please post updates (and a step by step!) either in this thread or make a new one. I am really intrested in this! How much did it cost for all the materials. How hard to build etc? :gay: :gay: :gay: :bigtu:

The hardest bit is trying to figure out the best way to lay everything out on the PCB. Once I've built one, the next one will be a lot smaller and more refined I'm sure! All the components should be widely available (I got my stuff from JayCar and Dick Smith), the cost all up was AU$18.31 (about US$13.30).

awesome, is there a write up on how to build one already? Becuase looking at the chart on the extra page just confuses the crap out of me. :bigtu:

What Knock sensor are you going to use?

3 296-1411-5-ND IC PRECISION TIMER 8-DIP 0 0.45000 $1.35
3 497-3106-5-ND TRANSISTOR NPN 30V .8A TO-18 0 0.99000 $2.97
3 296-1391-5-ND IC QUAD OP AMP 14-DIP 0 0.45000 $1.35
10 495-1636-ND CAP 10NF 250VAC EMI SUPPRESSN 0 0.47900 $4.79
10 620QBK-ND RES 620 OHM 1/4W 5% CARBON FILM 0 0.05200 $0.52
5 470QBK-ND RES 470 OHM 1/4W 5% CARBON FILM 0 0.05400 $0.27
10 10KQBK-ND RES 10K OHM 1/4W 5% CARBON FILM 0 0.05400 $0.54
5 39KQBK-ND RES 39K OHM 1/4W 5% CARBON FILM 0 0.05400 $0.27
10 399-3029-1-ND CAP 10UF 6.3V CERAMIC X5R 1206 0 0.71500 $7.15
3 ZTX688B-ND TRANS NPN 12V 3000MA TO-92 0 1.21000 $3.63
5 TIP122FS-ND TRANS NPN DARL 100V 5A TO-220 0 0.60000 $3.00

This is my digikey order, I ordered about 3x what I needed to build the knock sensor and then I threw in some ztx688b and tip122's while I was ordering.. I am not sure if all of these will work or not. But I will let you know if I get this circuit built...

Chris

I'd love to see how you've laid yours out because mine is looking like spagetti at the moment!

I will take a pic when I get it sorted out.

Do you have a part number for a GM knock sensor that works well with our cars?

Chris

Why not use a knock sensor off a NB?

why not use the one in the link I sent you guys in my first post. The guy sells them for 25 used and appears to be the same one FM uses with their link ecu's.

Any updates on how these sensors and the related wiring is working for you guys? Pics?

Nah, I gave up. Chris, did you finish yours?

If you have an NB8B or NB8C you don't need the KnockSense. Just follow the instructions and build this circuit:

http://megasquirt.sourceforge.net/extra/knock.html

Works like a charm on my NB8C!

I bought the knocksensor on the website listed in the first post. It's top notch quality, and works wonderfully. I highly recommend shelling out the dough, its very professional.

The same one I posted above, but I was too lazy to finish building it. Someone make an SMT version of this! :bigtu:

Can you share the knock sensor output with the stock ECU?

Apparently yes. I share it with the stock ECU and I have no problems (no CELs etc).

How do you know it's working? Have you datalogged any knocking?

Cheers

I datalog anytime I drive around since I have the incar pc. Yes there is knock and yes the knock sensor shows it. I can hear it, place a marker in MegaTune and when later on I check the logs in MegaLogViewer, I can see the knocks.

This is off-topic, but how do you place a marker in MT? Never heard of that.

On topic, here is an interesting thread on knocks sensors: http://www.corner-carvers.com/forums...ad.php?t=32308

Press the Spacebar while in Megatune. The marker will show up as a red vertical line in MegaLogViewer.

what sort of output does the knock sensor circuit put out?? im wondering if i could build one and log it on an emanage using the alternative logging software that allows extra inputs???Or could i just hook up a l.e.d on the dash??

5V -> No Knock
0V -> KNOCK!

Bear in mind that this is a "binary" output, there are no "levels" of knocking.

So, I've been doing a bunch of reading and wanted to pass on an idea for this. The Saab APC has an output that is grounded when knock is detected. All the MS needs is signal like this to detect knock. Advantages to this are:

-The APC is tuned to the specific sensor used. Less chance for false alarms.

-The APC box has an RPM input, which it modify it's sensitivity at higher RPMs. Once again less chance for mistakes.

The APC also can control boost, but that's a different story.

The modifications to the MS would be a 470R to 2kR 5V pullup resistor and bringing the signal in from the DB37.

I've got a snowboard-busted up knee, so I won't be able to make it out to the junkyard for a while. Thoughts?

do you have any links on the apc sensor? I'm interested in reading about how it works. Does it require you run the APC ecu somehow? The whole problem with a knock sensor is that you need something to interpret its signal.

The APC box does the sensor signal conditioning. The APC box is a stand alone with the appropriate knock, pressure sensor and boost solenoid. It is a very common swap on volvos. It does not need the Saab ECU. It's real purpose is to reduce boost when knock is sensed. It could control boost in our application also, but you have to add a pressure transducer and a few more wires.

http://www.pbase.com/740atl/apc_installation

very nice. Im going to track one of these down for my next build. Thanks!

This APC stuff is very interesting. I've decided to add a knock sensor before tweaking my timing map. I've got reading to do. Thanks.

Just tryin' to keep it "DIY" real.:bigtu:

Hurm, maybe i need to find the APC unit I got from the junkyards for consideration on my honda... miata could make better use I think.

Thanks for reminding me of it... i almost forgot I had the thing sitting in my piles of junk.

I talked to a Motec guy, who should know what he was doing tuning those WRC cars and he pretty much downplayed knock sensor saying that every time they change something in the car, the frequency the sensor looks for when knocking changes too and that causes a lot of false alarms or overreacting. And they do test a lot, even different exhaust changed the way knock sensor worked.
He did not treat knock sensor as tuning device, more like a suggestion.

hrk

True, but remember that the WRC engines are alot "noisier" than ours. Solid lifters, straight cut tranny gears, ect all create more noise to filter out to hear a true knock.

As for the last statement, definetly. If you crank up the advance and hope the knock sensor saves you, good luck.