SafcII Knock Question?

[OverboostXS]

I have been told that the knock sum given by the SAFCII is garbage. I am just a kid wanting to learn all i can, so i ask Why is the knock sum for the SAFC II not a real knock count? Thank You -Zach

 

[out there]

i don't remember exactly, but trust us that it's wrong. get some form of datalogging and read the more accurate knock sensor

 

[OverboostXS]

I have a logger, but I was just wondering the reasoning for having a knock count if it doesn't work.

 

[out there]

i prefer to use it as a general idea of how well i'm running, to see if i need to retune for the changes in weather. i know roughly where my counts should be at xpsi and xrpm
maybe i'm not using the right way, but it's working alright for me

 

[CanadianTSi]

i know roughly where my counts should be at xpsi and xrpm

You should have 0 counts all the time...

And it doesn't seem to work very well with the DSM knock sensor esp. 2g's. The S-AFC was designed for all cars, not just ours.

 

[out there]

i don't know about your car, but just when i was calibrating it, i was getting double-digits of knock count

 

[steve]

The ECU knows far more about whats going on that the SAFC ever could. When it comes to Knock all the SAFC can do is compare the output of the sensor when the car isn't knocking (when you calibrate it) to what it hears the rest of the time. It has no way of knowing if the noises picked up are happening during the time period that a cyl would knock if it was going to. So the SAFC knock function just tells you that your engine is noisier than it was before.

After looking into it, I didn't even bother to hook it up on mine.

Steve

 

[out there]

and to change the subject... in theory, could the safc properly count knock if calibrated to the gear that you need it to count for ???

 

[steve]

In theory, could the safc properly count knock if calibrated to the gear that you need it to count for?

The SAFC won't ever tell you what the ECU considers knock and that's the only knock that matters from a performance perspective. 1G dataloggers are cheap, get one if you don't have one.

Steve

 

[out there]

i have one, i'm trying to figure out a way that it might be able to read the proper knock. i think it doesn't work mainly because it's calibrated with the engine not bearing a load

 

[XtReMeToYz]

The SAFC won't ever tell you what the ECU considers knock and that's the only knock that matters from a performance perspective. 1G dataloggers are cheap, get one if you don't have one.

Steve

I think that about covers it.

 

[COHIBAGSX]

So knock on the SAFC II should be at 0 or the closes possible to 0 at all times? I dont have a data logger. Also when setting the Hi & Lo according to RPM on the SAFC II does the +- mean more/less air or fuel? Thanks.

 

[steve]

So knock on the SAFC II should be at 0 or the closes possible to 0 at all times? I dont have a data logger.

That would be nice but the SAFC knock values are meaningless for tuning. At best seeing knock on your SAFC would be cause to investigate what's going on. Just like using an blinkly light A/F guage, it's a way to monitor engine status for unusual activity. It's well known that you can see tons of knock on a SAFC II and have the ECU report 0 knock.

Also when setting the Hi & Lo according to RPM on the SAFC II does the +- mean more/less air or fuel? Thanks.

+ corrections mean your increasing the airflow Hz value to the ECU , - corrections mean your reducing the airflow Hz.
The Karmen airflow signal on our cars is a variable frequency. The more airflow the higher the frequency. Simplified, + = more fuel, - = less fuel at that RPM

Steve

 

[COHIBAGSX]

STEVE MY AFC IN THE MONITOR SETTING READS KNOW FROM 5-9 OR SO. THE A/F STARTS OFF ON RED (LEAN) BLINKING THEN GOES TO THE LAST BLOCK OF YELLOW BEFORE GREEN (RICH). WHEN I STEP ON IT IT GOES TO RICH ABOUT 2-3 BLOCKS. WHEN I LET OFF AND ITS AT IDLE ITS READING RICH. SOMETIMES IN 1ST GEAR THE CAR BARELY BOOSTS. ONCE IT GETS WARMED UP IT STARTS BOOSTING. 1ST 12-13PSI, 2ND 15PSI, 3RD 17-18PSI, 4TH 20PSI. I HAVE MY PROFEC-B ALL THE WAY TO THE MAX ON HIGH. I KNOW MY MIXTURE IS RICH RIGHT NOW WAITING FOR MY MSD IGNITION TO START TUNING IT. MY OLD IGNITION WAS INSTALLED WRONG AND WAS DAMAGED.