How to read knock on aem
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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
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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.
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.
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