Adding knock sensor to AEM EMS - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-09-2009, 12:32 PM   #1
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Default Adding knock sensor to AEM EMS

I have a 30-1710 AEM EMS I am having someone help me set up a wire harness for my engine for it and I would like to add a knock sensor eventually. I looked at the PDF file for the EMS and it mentions one pinout for a knock sensor but I wasn't sure what i need to do to wire one in and what would be a good one to use. If anyone can give me some wiring advice for it and if i should look for a stock miata one from a certain year or some kind of aftermarket one that will work with the miata.
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Old 04-09-2009, 01:28 PM   #2
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Search for one sold by Boris. It's called Knocksense. It'll do the job. You'll have to fine tune it.
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Old 04-09-2009, 02:06 PM   #3
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Engine knock detection and indication for all vehicles is this the one? while i was previously searching the knocksensems was the onely one i saw come up and a lot of times complaints were associated with those discussions i believe you even posted saying you weren't impressed with its efficiancy. So is this a waste of time? is a knock sensor in general a bad idea? I didn't look into the knocksense before also because i assumed the ms on the end meant it only worked for the megasquirt not the AEM EMS also
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Old 04-09-2009, 03:03 PM   #4
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Engine knock detection and indication for all vehicles is this the one? while i was previously searching the knocksensems was the onely one i saw come up and a lot of times complaints were associated with those discussions i believe you even posted saying you weren't impressed with its efficiancy. So is this a waste of time? is a knock sensor in general a bad idea? I didn't look into the knocksense before also because i assumed the ms on the end meant it only worked for the megasquirt not the AEM EMS also
That's the one. It takes time to fine tune it. It's not put it in and forget about it. You have to tinker with it after installing it. Ask Savington; he dialed his in pretty well.

The AEM will recognize it.
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Old 04-13-2009, 07:12 PM   #5
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You can use a saturn knock sensor for the EMS. Search the AEM forums for details. You have to run a shielded wire to the sensor and mount it to the block using a modified bolt. I've got one installed but I haven't got it working real well yet.
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Old 04-14-2009, 06:57 PM   #6
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Search for one sold by Boris. It's called Knocksense. It'll do the job. You'll have to fine tune it.
No, you can't use that (it can't interface with the EMS) and it won't do the job reliably either.
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Old 04-14-2009, 06:58 PM   #7
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You can use a saturn knock sensor for the EMS. Search the AEM forums for details. You have to run a shielded wire to the sensor and mount it to the block using a modified bolt. I've got one installed but I haven't got it working real well yet.
+1. The resonant Saturn sensor is the one he needs.
Flat response sensors won't work.
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Old 04-14-2009, 07:00 PM   #8
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Engine knock detection and indication for all vehicles is this the one? while i was previously searching the knocksensems was the onely one i saw come up and a lot of times complaints were associated with those discussions i believe you even posted saying you weren't impressed with its efficiancy. So is this a waste of time? is a knock sensor in general a bad idea? I didn't look into the knocksense before also because i assumed the ms on the end meant it only worked for the megasquirt not the AEM EMS also
Do not use that. You don't need to buy this device because it can't interface with the AEM EMS. You'll be wasting your money.

Last edited by j_man; 04-15-2009 at 01:05 PM.
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Old 04-14-2009, 08:55 PM   #9
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+1. The resonant Saturn sensor is the one he needs.
Flat response sensors won't work.
I am using a flat response (bosch?) knock sensor on my aem ems and it does work. Not ideal due to the low voltage but it does work.

It's a leftover from my link ecu days.
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Old 04-15-2009, 09:22 AM   #10
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I looked through the aem website searched miata nock sensor / saturn knock sensor / and nock sensor couldn't find any info though. when adding the wire or wires into the harness for the knock sensor do i add only one or two? The AEM single Pinout do i run one wire from there only or do i add a second "ground" wire to the aem pinout somewhere also? and honestly which one would be best for the knock sensor a wideband bosch one or that saturn one (and if i get the saturn one which engine is it from?) one i get it done i'll post most info and a howto (this could be a while though since I still have a decent amount of work on the car to make it run)
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Old 04-15-2009, 01:02 PM   #11
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I am using a flat response (bosch?) knock sensor on my aem ems and it does work. Not ideal due to the low voltage but it does work.

It's a leftover from my link ecu days.
Yeah, I used one with my AEM EMS (Bosch one which came with my Knocksense back then) too, but it was giving false alarms - maybe my car is noisier (maybe because of the supercharger whine). The Saturn one works better. The reason is unlike the Link, the AEM EMS doesn't have a built in bandpass filter so you even strong non knock frequencies are seen as knock from the ECU.
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Old 04-15-2009, 01:12 PM   #12
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I looked through the aem website searched miata nock sensor / saturn knock sensor / and nock sensor couldn't find any info though. when adding the wire or wires into the harness for the knock sensor do i add only one or two? The AEM single Pinout do i run one wire from there only or do i add a second "ground" wire to the aem pinout somewhere also? and honestly which one would be best for the knock sensor a wideband bosch one or that saturn one (and if i get the saturn one which engine is it from?) one i get it done i'll post most info and a howto (this could be a while though since I still have a decent amount of work on the car to make it run)
Check BarryK's post in this thread - it has the part number:
MX-5 Miata Forum - Who's running a knock sensor with the AEM EMS?

You can get the connector either from a GM car in some junkyard, or order one along with your sensor from places like www.rockauto.com (that's where I got both my sensor and connector from there)

I use a shielded wire for the signal. If you do too, connect only one end of the shield to chassis ground. Besides that, the connection sensor to EMS is just one wire.

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Old 04-15-2009, 01:38 PM   #13
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The reason is unlike the Link, the AEM EMS doesn't have a built in bandpass filter so you even strong non knock frequencies are seen as knock from the ECU.
Which is also why the AEM EMS only looks within a certain amount of degrees from a spark event to register it as knock, to attempt to cut down on false triggers. Again, technically not the most ideal but still pretty slick and better than nothing at all.

Knock should be louder than anything else around a timing event.
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Old 04-16-2009, 09:01 AM   #14
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I think i found the knock sensor... it is the one for 1991 - 1995 Saturn SC and SL as well as the 1993-1995 SW series. now to figure out how to weld a nut onto the cylinder head if i read his instructions right. I really don't need the knock sensor yet but i'm still going to look into the stuff for it if it isn't too pricey i may go ahead and buy it and install it now so that by the time i get the turbo added to the car the knock sensor will already work
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Old 04-16-2009, 01:35 PM   #15
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I think i found the knock sensor... it is the one for 1991 - 1995 Saturn SC and SL as well as the 1993-1995 SW series. now to figure out how to weld a nut onto the cylinder head if i read his instructions right. I really don't need the knock sensor yet but i'm still going to look into the stuff for it if it isn't too pricey i may go ahead and buy it and install it now so that by the time i get the turbo added to the car the knock sensor will already work
I bought the nut from the local hardware store then brought it along with the engine mount bolt to the exhaust shop around the corner and they welded the two - they didn't even charge me because it was like a 2 minute job (I just tipped the welder)
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Old 04-16-2009, 01:50 PM   #16
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I bought the nut from the local hardware store then brought it along with the engine mount bolt to the exhaust shop around the corner and they welded the two - they didn't even charge me because it was like a 2 minute job (I just tipped the welder)
Can one use the one that FM sells?

BTW j_man; I stand corrected on the knock sensor. I just reread the thread on m.net about the subject. This is the second time you suggest it to me and I simply forgot. That's what old age does to me!
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Old 04-16-2009, 02:09 PM   #17
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you put it on the engine mount rather than the cylinder head?
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Old 04-16-2009, 02:18 PM   #18
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FM's goes on the engine mount. All knock sensors I've seen in OEM apps go on the engine block, not the cylinder head. I haven't seen much though.
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Old 04-16-2009, 02:38 PM   #19
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you put it on the engine mount rather than the cylinder head?
If you put it in the cylinder head you'll encounter a lot of interference from valve noise.
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Old 04-16-2009, 03:34 PM   #20
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so it either goes on a particular mount or it goes on the engine block... i need to find a miata i can look at
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