How to: Use an safc2 to monitor knock on the 3sgte Options

[lagos]

I recently upgraded my safc1 to the safc2. One of the new features in the safc2 is the ability to monitor knock. However after doing some research on the topic, I kept hearing everyone say that the feature doesn't work correctly with our cars because it seems to report a knock count, even when there is no knock.

I decided to look into this myself, especially since my car has had some detonation issues. I started to notice a patten in the knock readings the safc2 was showing. What I noticed is that the knock number was always higher when my car pulled timing, and alot lower when it was not. I decided to contact califcarm to help me figure out if what I'm seeing is correct. He was able to verify my theory and help figure out exactly what is value is knock and what is just normal engine noise by monitoring his JS Safeguard for a knock count and comparing it to what the safc was reporting.

Now before you try to monitor these values, you need to look at your safc2 owners manual to setup your noise profile. There is a knock menu in the safc, where you rev to 1500, hold the rpm, and sample the noise print. Then you do the same thing at 3400rpm. The safc then uses those two values to extrapolate the rest of the data for your noise profile.

Here is what we found:

0-169 knock = Normal engine noise with zero knock
170-175 knock = On the verge of knock. Car is most likely making the most power, but you are running on the edge.
176-185+ knock = This is where most knock happens. The stock ecu might not react to these values alone, but there is definitely some detonation going on.

Now its important to note two things. First, there is no one magic number that will make the car fall into safe mode from knock. Instead the ecu waits till a few knock events (a few small or a few big) before it falls into safe mode. I have seen my car go up to 185, and not pull timing. Then right after that run, I hit 172 and the ecu went into safe mode and pulled timing. This is because it already remembered the first large knock count... tried to correct it, but saw another smaller knock count and decided to step in.

The other thing that needs to be mention is to take these figures with a grain of salt, and use them at your own risk. Since every car has a different noise profile, its possible that these values might be slightly different from car to car. However they DO seem to be consistent for me and califcarm.

I would also love to hear back form a few safc2 users to see what kind of knock counts they normally get under different conditions. This could be very useful tuning tool, especially those trying to use the safc to tune with alcohol injection.

[bccentaur3]

This is whats got me stumped. I wired up the knock wire as the manual states, BUT I am not getting any knock values what so ever. What do you think is the problem.

There was even a case where my ecu put me into safe mode with no knock.

[lagos]

You didnt set up your noise profile in the knock menu like i said to do above. Check the owners manual.

[bccentaur3]

Alright will do boss. Thanks a lot.

[DEATH]

Allright - this gives me an excuse to wire my SAFC-II up this weekend and set the value like you said and I'll report back next week what my readings are. Might as well get in there and do your LED mod too.

[bccentaur3]

I will report back too, but my car isn't running yet. Still waiting for my clutch disc.

[lagos]

Allright - this gives me an excuse to wire my SAFC-II up this weekend and set the value like you said and I'll report back next week what my readings are. Might as well get in there and do your LED mod too.

Thats what I like to hear.

[presure2]

just FYI art, i'd say with the 5sfte, those #'s are just about in line with what i seen when i had the SAFCII installed, as long as i ran a 50/50 mix of race fuel. lmao.
i'd normally see higher values in general without the good stuff.

[lagos]

Thats awesome! Now we have more proof that the knock feature works and makes for a good tuning tool. It should be a great benefit for 5sfTe guys as well.

[Tigawoods]

in the past, my numbers went no higher that 120

id did save me once when it was generating high numbers at idle, checked the oil and there was none ( during my oil burning phase )

the safc2 saved my life. i havent seen any knock numbers since then

[WALKER]

Right now I just have the 5SFE, with that I have my low rpm (1500) background noise set at 36 and my high rpm (3400) background noise set at 106. With that setting I will normally don't see any higher than 50-75 on a WOT 4th gear run. On a hot day with a WOT run I have seen it as high as 106. Just to give you an example of my numbers.

[lagos]

Right now I just have the 5SFE, with that I have my low rpm (1500) background noise set at 36 and my high rpm (3400) background noise set at 106. With that setting I will normally don't see any higher than 50-75 on a WOT 4th gear run. On a hot day with a WOT run I have seen it as high as 106. Just to give you an example of my numbers.

So your knock numbers would probably be a lot different then mine, because your motor generates less ambient noise.
keep these numbers in mind for when/if you ever turbo your car. That way you'll have a point of reference of what value meant 0 knock.

[WALKER]

Right now I just have the 5SFE, with that I have my low rpm (1500) background noise set at 36 and my high rpm (3400) background noise set at 106. With that setting I will normally don't see any higher than 50-75 on a WOT 4th gear run. On a hot day with a WOT run I have seen it as high as 106. Just to give you an example of my numbers.

So your knock numbers would probably be a lot different then mine, because your motor generates less ambient noise.
keep these numbers in mind for when/if you ever turbo your car. That way you'll have a point of reference of what value meant 0 knock.

That is exactly what I am doing. Just getting a baseline for when I throw on the CT27! Just thought I would post them up here though.

[lagos]

This also brings up something I thought of before. Maybe Manny can shed some light on this..
Since the 5sfe is an NA motor tuned for 87gas, its ecu is probably programed to make much smaller corrections during detonation. I wonder how much actual timing it pulls and how much of that you can feel while driving the car?
In the 3s, when the ecu pulls timing, you feel a huge shut down in power. I cant imagine the stock 5sfe ecu being programed with such large timing retard. Im willing to bet that because of this, at lot of 5sfTe guys might have detonation they cant really feel?

[presure2]

This also brings up something I thought of before. Maybe Manny can shed some light on this..
Since the 5sfe is an NA motor tuned for 87gas, its ecu is probably programed to make much smaller corrections during detonation. I wonder how much actual timing it pulls and how much of that you can feel while driving the car?
In the 3s, when the ecu pulls timing, you feel a huge shut down in power. I cant imagine the stock 5sfe ecu being programed with such large timing retard. Im willing to bet that because of this, at lot of 5sfTe guys might have detonation they cant really feel?

ohh no, art.
trust me, when you knock with the 5s, you'll know it.

[lagos]

Ah, thats good!

[bccentaur3]

I did this and The highest I ever went is around 140. I am running around 10 psi too. I accidentally turned the boost up to 17psi and number doesnt jump past knock point. I also have the led knock mod too. Funny thing is, when I went to 17 psi I didn't even hit fuel cut. I have a 93 jdm swap.

[lagos]

what is your peak air flow % ?

[bccentaur3]

To be honest I don't even look at that. Why? Does it play a role in how I can boost with no fuel cut? Its going ot be a while until I can check because I'm waiting for my fmic set-up.

[lagos]

You can run more boost because 93s had their fuel cut raised to around 16psi. Depending on your elevation and how accurate your boost gauge is that could be higher.

I want to know your air flow % because mine wont go above 55%.