mschlang

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

timk

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

Reverant

iTrader: (10)

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!

karter74

iTrader: (4)

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.

timk

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

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

Reverant

iTrader: (10)

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

timk

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

Cheers

Reverant

iTrader: (10)

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.

mschlang

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

Reverant

iTrader: (10)

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

4sfed5

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??

Reverant

iTrader: (10)

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

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

mschlang

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?

neogenesis2004

iTrader: (12)

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.

mschlang

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

neogenesis2004

iTrader: (12)

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

Al Hounos

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.

mschlang

Just tryin' to keep it "DIY" real.

Splitime

iTrader: (24)

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.

hrk

iTrader: (6)

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