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How to read knock on aem

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Old Nov 6, 2012, 05:38 PM
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How to read knock on aem

Hello I have aem ems series 1 and I'm learning how to tune my car but alittle confused on how to read knock..Can some one shead some light on how to do so ..Some one told me you read it with volts and I want to know whats the safe volts it should read on a full throttle pull..I been into dsm's for years and was pretty good tuning dsmlink which was very easy cause it would read knock count but aem doesn't have that..thx
Old Nov 8, 2012, 02:29 PM
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First off, you should look @ your knock stuff from internal logs.

log rate should be set @ 250/sec.

put these 2 parameters in the "FAST" section of the internal log list

Knock #1 volts
Knock #1 retard

if you dont view internal log data for this, your fooling yourself.

personally, I would set your car up to be med boost, ~14 psi, ignition map set safe, & conduct a few 3rd gear pulls from ~3k revs to redline.

what your trying to do is establish a basaeline knock sensor profile for your engine. In theory, everything should be happy & afr's are ok, your not knocking too.

so per the rpm break points within the knock sensor cal table, find your highest voltage value, +/- 100, take that voltage & mulitply it by 1.25

so when you zoom into your pull, you will look @ knock #1 volts, this output will be a little choppy, but if you see a voltage spike ~1.00 volts more than either side of the spikes other high points, consider that individual spike to be knock.

for example, @ 4073 rpm, you saw a 1.05 voltage spike, keep in mind that the sensor output is jagged, but nothing crazy jagged. so take that 1.05 * 1.25 = 1.3125 is your knock sensor cal table value for 4000 rpm.

do this for all the rpms you will be going thru... basically 2400 up to your redline.

this will then give you a offset. any voltage higher than those values, ignition retard will occur.... thats if you have your ign retard set-up correctly.

hope this helps.

Last edited by Aby@MIL.SPEC; Nov 8, 2012 at 02:37 PM.
Old Nov 8, 2012, 05:53 PM
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Oh wow that seems like alot of work lol ..Another question i have is when i do A 3rd gear pull in my car its only running 2 degrees of timming ..is that normal?
Old Nov 9, 2012, 10:31 AM
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Honestly, you need to take the car to an AEM certified tuner. Where are you located?
Old Nov 15, 2012, 07:04 AM
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Originally Posted by 99EclipseGSX
Honestly, you need to take the car to an AEM certified tuner. Where are you located?
+1

Besides, what i described should take ~30 minutes of your time to get your knock cal profile established.

if that is a lot of work, then please takes 99EclipseGSX's advice.

GL
Old Jan 17, 2013, 12:05 PM
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hmm

Originally Posted by Aby@MIL.SPEC
+1

Besides, what i described should take ~30 minutes of your time to get your knock cal profile established.

if that is a lot of work, then please takes 99EclipseGSX's advice.

GL
what sort of timing you call conserative for 14-15 psi to make the pull?
Old Mar 14, 2014, 06:42 PM
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Looking for some tips on knock control since the AEM forum is down for a while now

how much spark do you guys pull back & percentage fuel you add when knock is sensed?
Thanks
Old Mar 17, 2014, 09:48 AM
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i pull 5 deg max
retard 2.2*/V
restore 10/rev
spark adv 1.41deg

imo, fuel is a waste of time, since spark is immediate, with fuel, your waiting on transport delay.
Old Mar 17, 2014, 01:43 PM
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Old Mar 17, 2014, 07:37 PM
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Originally Posted by Aby@MIL.SPEC
i pull 5 deg max
retard 2.2*/V
restore 10/rev
spark adv 1.41deg

imo, fuel is a waste of time, since spark is immediate, with fuel, your waiting on transport delay.
Awesome man! thanks for the tips. Many vendors would probably not share this kind of info
I agree with you on the fuel response, but figured since its calibratable then why not use something more proven than what's in the Aem very base map.
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