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Ex Skylineowner
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Discussion Starter #1
Installed my second hand SAFCII the other day. Initialised (reset) it and entered all the setup details for my car and it all runs fun. Good stuff. Onto the knock reading setup. The base reading at the top above the 2 rev point readings was sat at 56, scroll down and hold the revs at 1500 - 56 again, down to the 3500rpm setting and get 58. OK, i think? Into the monitor knock, X has gone from the 0 reading and seems to monitoring fine.

Went out for a drive today about 90 mins each way. Was reading 0 for about the first 40 mins on the way out then started to creep up slowly, i mean very slowly but got up to about 15 by the time i reached my destination. There was no spiking and when i put the foot down the reading actually dropped back down to 0/1/2 before climbing back up to the highest reading before. Let the car cool down for few hours then a pretty much identical story on the return leg but only creeped as high as 10.

Any theories, suggestions or calming words much appreciated. Next step was to splice into the other sensor (front 3 cylinders) and see if i get different readings there.
 

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Are you sure it is a problem Darth? I do not have any working knowledge of the S-AFC but know from running a power fc that low level knock readings would be perfectly normal.
 

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Ex Skylineowner
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Discussion Starter #3
Thats the thing, having never monitored knock readings i don't know if these figures are normal or not?
 

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mine does the same, i think mine might be something to do with the fact ive got no sound proofing on the bonnet and that the engine bay temps may be effecting it cos now the bonnet gets quite warm.
im getting some vents cut in to see if thats any better
 

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Ex Skylineowner
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Discussion Starter #5
Nice one :) So the consensus so far is nothing to worry about. Just need to save pennies to get it set up properly now :(
 

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The knock values on the SAFC 11 are meaningless, they are for reference only, different knock sensors from different manufacturers will show a different reading for the same knock too, eg 10 on one make of sensor might be ok but with another make of sensor 10 might be doing damage.

The idea of them is so when you measure the knock with eg det cans, you can use the values as a reference to when you heard det.

The other thing worth noting is that these sensors are designed to pick up a certain frequency and there are other things in a car that under certain conditions will emmit the same frequency and give you a false reading (usually just a random spike tho)

also

When you start changing parts like exhaust manifolds, turbos and camshafts etc they can have an effect on the frequency that emmits when det is occouring, hence better checking it with det cans too.

Since the SAFC 11 is altering the airflow signal the ecu will be altering the ignition timing relative to the standard maps, if the correction factor is extreme, the ingition timing may not be ideal. :)
 

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Ex Skylineowner
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Discussion Starter #8
Cheers for the posts. I had heard that the knock values weren't to be treated as anything other than a guide. I was more just interested in whether or not the way mine were changing were anything out of the norm (ie-creeping slowly up the longer the car was run)
As all the correction points are currently zero then not too worried about the timing yet but i will certainly keep it in mind for when it gets put on the dyno

:cheers:
 
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