Tuning the roomates car, we did a pull, from 3k-4k afrs were 10.4-10.8 with great timing, everthing in spec. The car IMMEDIATELY pulled 8 counts at 3.1k then 22 counts at 3.2k dropped to 21 at 3.25k then 29 at 3.4k then 36 at 3.5k all the way to 4k i LET OFF the gas and 200rpms later still had 33 counts of knock.

Turn around, wondering about my issue, I at idle revved the car to 2k, 3k and 4k. Ended up getting anywhere from 1-12 counts of knock at different times.

Compression is 174 172 171 174, motor sounds perfect, no shavings in oil. Checked all vibrations, can't seem to see anything that would be traveling. I put a stethoscope near the area of the knock sensor, didn't hear any vibrations or noises.

Faulty knock sensor?

WB is purple
knock is pink
rpm is tan

 

Throw some q16 in and ensure that its not real knock.... once ure certain, play with the knock sensitivity threshold values.

My motor was loud after my build and i was getting phantom knock in the 2.5-3.5k range. I bumped up form the stock 13,17,20 to 18/21/21 and that solved it. My knock responses normally to timing now ~3 counts / degree.

Another thing to check is to ensure the washer was replaced between the sensor and the block.

 

I ordered a new knock sensor from Buschur. I did a pull today on the interstate from 3,800rpms to 7k. Got 1 count of knock in a spot half way threw the pull? but then i 2step, i get 1-3-12counts? or as shown before just rev it up to 2k rpms and get knock still? I'll post graph asap

 

if you need help tuning the knock sensor you can pm me.. i advice you to check the engine thoroughly though for anything rubbing, hitting, loose, etc.. typical things to cause a false knock are the o2 housing heatshield (if the car has it still), the downpipe may be hitting oil pan (if it has horrible fitment), the way the wideband is routed under the car ( wire/connector could be banging against the heatshield)

make sure the ic piping is not hitting anything and you can wobble it up and down, left and right, and no contact with anything.. bov not hitting the radiator fan shroud, etc etc

valvetrain could be causing it too, or a overly noisey clutch.

things like that..

 

on the dyno getting tuned my car was fine, then leaving a day later getting phantom counts of knock and not all the time either. Im hoping something is loose somewhere and maybe making some noise

 

Log knock voltage and look for peaks especially in areas like decel which its common to see rattles occur and the knock sensor will pick it up as a voltage spike but there will be no knock since the load is below threshold.

Max voltage for the sensor is 5 volts if i recall in case you want to see how hot its running.

 

Im having this exact same issue with my 05. Im pretty sure it started when i put in the cams but im going to check everything that tscompousa said to see if i can find something rattling. I guess i can start by checking the voltages as described by roadspike first

 

What clutch and how many miles?

It seems so often the solution is fix the knock tables... Funny thing they haven't been around that long to modify.

Probably not a sensor issue but something causing it to happen.

 

bump, were you able to find out the cause of the phantom knock? I'm having the same issue