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Old 02-08-2018, 04:58 PM   #1
Greenvolv
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Default Anyone else running AEM?

I'm running an AEM infinity and trying to figure out if I'm having a setting issue or mechanical issue with the knock sensor. The raw voltage from the sensor seems low but I've tried swapping knock sensors with same readings. Messed around with some of the settings in the software but it doesn't seem to change very much.
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Old 02-12-2018, 12:05 PM   #2
LDSNOMAD
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I'm running a AEM EMS-4 however I need to finish it.
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Old 02-12-2018, 12:31 PM   #3
Mogly
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throw that knock sensor away
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Old 02-12-2018, 04:28 PM   #4
Greenvolv
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I have knock sense disabled for right now but would like to be able have it on for peace of mind. Is there a different knock sensor that works better?
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Old 02-12-2018, 06:59 PM   #5
Mogly
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Try running a newer knock sensor, something like out of a BMW.
MTC knock sensor, Vemo knock sensor and the KTuned knock sensor work good.
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Old 02-12-2018, 08:30 PM   #6
Mogly
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Is this setup running on a redblock?
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Old 02-12-2018, 09:43 PM   #7
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Knock sensors don't produce any voltage unless they're vibrating / knocking. If you have an oscilloscope, you can set it to a low voltage (1volt/div or lower) and whack lightly on the knock sensor with the handle of a plastic screwdriver and see the sensor output voltage.

From this writeup: http://www.efi101.com/forum/viewtopic.php?t=7972
the older AEM knock setups were tuned both to a knock frequency range and a window of crankshaft rotation. Whacking the sensor with a screwdriver at just the right times to hit the detection window(s) is probably very difficult.

I'd do some searching, or email AEM, and see if they have a good writeup on how to setup knock parameters for your ECU.
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Old 02-13-2018, 04:59 PM   #8
Greenvolv
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I'll look into using one of the knock sensors you've listed Mogly. Is there one you like using more? Yes this setup is for an 8v redblock. ECU shows raw knock sensor voltage at 0.03-0.04v at idle and highest voltage at 0.94v from logs. I've set the knock sense to start at -20 btdc with a window of 50 degrees. Bandpass center frequency is at 6.64 Hz, amplitude gain is set has high as it will go at 2 and I've dropped integrator smoothing time down to 40 us. Does anything jump out as unusual? Do you happen to know what normal knock sensor voltage readings are when audible knock is heard bobxyz? Audible knock seems to happen when ecu is showing knock sensor raw voltage anywhere from 0.70-0.90v but seems to occur randomly in that range. I've emailed AEM but seem to only get general answers to my questions so I was hoping for more help on turbobricks.
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Old 02-13-2018, 08:33 PM   #9
Mogly
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And you are trying to get this function to work just Incase of bad fuel?
What features are offered when knock is detected with your ecu?
I heard of some tuners finding valve train issues, bad fuel and things like that with knock detection on. So Iíve destroyed a B230 at around 30psi because of bad fuel. Iím sure it knocked then went boom but my exhaust is loud. So I understand what you mean by peace of mind now. I will have to get my knock sensor out of the trash
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Old 02-13-2018, 09:42 PM   #10
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I've not tuned an ECU with knock detection (but I have tweaked the one adjustment pot on a standalone KnockSense box), so these comments are just a guess. Your setup and voltages seem reasonable: voltages up to a volt, ~6kHz center frequency, gain of 2, and a small integration window to get a bigger signal.

If you look in the Volvo 31397-1 Ignition Greenbook, it talks some about EZK-116 knock detection. It mentions a 7.5KHz center frequency, which is a bit on the large side for a 96mm bore and traditional resonance mode equations. It also says EZK uses a window of -15 btdc to +55 atdc, which seems a big big.

Have you checked that your knock sensor mounting boss and sensor bottom are smooth (no corrosion), and that it's torqued properly?

gross polluter on here worked a lot with the MS3 knock detection during development. The MS3 detection is similar to AEM, but looks like it's not as advanced for responding to knock once detected.
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Old 02-14-2018, 04:34 PM   #11
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I'm trying to dial the knock sense in so I can advance timing as safely as possible. My hearing isn't what it used to be either. The ecu has separate ignition and fuel controls for knock. Sensor boss is clean, chased bolt threads as i had used lock-tite on the bolt and was unsure if that was causing the issue when knock sensor was swapped. Torque wrench was used to bolt sensor to block and I think I had tightened it 1 ft.lbs. tighter then spec. I'll try changing bandpass frequency to 7.5 kHz and see what happens.
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Old 02-16-2018, 11:04 AM   #12
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use a dyno, preferably one with an eddy brake, to dial in timing.. you may find that it doesn't want timing right on the threshold of knock. Using a knock sensor to dial that part of the equation in is generally not a great idea.

if that's not available, careful tuning at a dragstrip will tell you if a change has made more power or not (looking at trap speed specifically).
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