Safc 2 Knock Level

[so_tred]

I did the whole set up step of the knocking levels, was getting about 80 at 1,600rpm & 92-100 at 3,500rpm (in set up screen - not monitor)

so then I put it in monitor mode and it says around 4 while idling but then drops to 0 whenever the throttle is open..

I set it up once the car was warm & took it for a drive once the car was also warm & that's the reading I got..

(I've got an R34 with 35,000kms on the clock)

Ideas as to why it drops to 0?

[paulr33]

its not meant to constantly knock

it should only knock when detonation is occuring

so usually when the engine is on load

i would be surprised if its knocking at idle

[Eug]

i just bought an safc2 myself (havent installed it yet)

but as i understand it - you are meant to subtract the "stock" knock figures from the "tune" knock figures... no?

since it's a microphone you'd get knock anyway - but since the "stock" knock figures are normal, you would ultimately make that zero?

[paulr33]

what the ?

the knock display on the powerfc is bar chart and digital counter output which goes up as the knock is larger

ie: knock 0 means no knocking. knock 40 is mild, knock 60 is warning, knock 100 is bad etc etc..

normal driving should be 0 or very very low

[Eug]

what the ?

the knock display on the powerfc is bar chart and digital counter output which goes up as the knock is larger

ie: knock 0 means no knocking. knock 40 is mild, knock 60 is warning, knock 100 is bad etc etc..

normal driving should be 0 or very very low

yes, but who sets normal driving = 0 knock? certainly each car has a different "normal"

[Strik3r]

rule of thumb - SAFC should read below 20 during normal cruising.. up to 30ish if your giving it a bit on a hot day... if your seeing 40 and up regularly then you might have some probs.

[so_tred]

So why the hell is mine reading 4ish when its on idle but 0 when it's being pushed

I'm going to have another play around with it today (do the knock settings step again) and see what I come up with..

[Cubes]

rule of thumb - SAFC should read below 20 during normal cruising.. up to 30ish if your giving it a bit on a hot day... if your seeing 40 and up regularly then you might have some probs.

This about right.

[so_tred]

Ugh, I tried resetting the knock sensor information and I'm still getting the same problem!

In the setup screen it's on about 63ish at 1,400rpm and 80-90ish at 3,400rpm yet when I take it to the monitor mode I still get 2,3,4 displaying in neutral with the throttle closed but as soon as I put my foot down a little it just jumps to 0..

I'm doing all this while the car is completely warmed up - oil temp wise.

[Strik3r]

this is normal.. it has to do with how the SAFC interpolates knock values.. you will often find that after a long driving session (where your knock might have been say 10-15, you will come to rest in neutral and the knock will jump up 8-10 while idling. dont worry about it.

[so_tred]

but I'm not getting any knock reading while driving..that's my problem..?

I did a bit more of an investigation:

0 Knock readout in Drive at all times

1-4 when in Park or Neutral

WTF?!

Edited April 10, 2007 by so_tred

[so_tred]

bump, I really want to figure this out..

The 34 has 2 knock sensors coming in/going out of the ECU, could it be that the other knock sensor might somehow respond differently? I really don't want to go pulling things apart again though unless its for sure that's what it is.

I just found this on another message board:

"I was wondering what other peoples knock readings were. WHile at idle, my knock reading goes anywhere from 2 to 16. When I give any throttle at all, the knock reading goes to 0 and stays there."

Reply: "I think at idle your picking up valvetrain noise and other noises.. Low idle you can hear rattles and other noises that you normally wouldn't associate with engine knock.

Even at low RPM its possible to pick up noise.. The truth is that knock sensitivity needs to be fairly numb at low RPM especially at idle, and progressively more sensitive at mid-upper RPM's where you'd typically produce the peaks of boost and up from there.."

Sound about right?

But why does everyone elses here not behave like mine & this guys..

Edited April 10, 2007 by so_tred

[paulr33]

i have no idea how the safc figures out its knocking levels but the powerfc does exhibit any of this behaviour

you dont need to calibrate the pfc knock sensor and it just works out the box.

you get knock display which increases as detonation occurs, via the factory knock sensors

the higher the voltage from the sensor, the higher the value of knock

[paulr33]

have you read the safc2 manual ?

[so_tred]

Yeah, the manual doesn't say much apart from how to set up the knock correction (which I've done)

Edited April 11, 2007 by so_tred

[paulr33]

let me look tonight ill see what i can find out

[Kaz200]

Michael gets high figures like (80-200) in his RB20 if he floors it onto the freeway. Not too good

I leave my car in the sun alot and it's always knocking when I start the car in summer Runs like crap in the heat... of course I think my coilpacks might be fried which doesn't help