SAFC2 knock readout

[Zahos]

One thing I haven't figured out yet is the knock reading on the SAFC2...

The reading kept telling me 0, so I got into:

settings -> Knk level

and set the knock levels for 1650 and 3650 rpm to whatever they were at the time (45 I think??)

Anyhow, if I stay on that screen, as the car warms up the knock reading goes to about 100. If I go to one of the screens in the monitor section, the knock goes up to about 10 on idle, and down between 0 and 3 when driving...

Can someone tell me what the differences are? I have no idea what either mean now

Thanks

George

[DJ_L3ThAL]

can i please have the wiring for the knock wire for the SAFC2 please... only thing i didnt hook up when i did mine, then i can let you know if i get the samr readouts

[T0nyGTSt]

The knock readout (if it is the same as the PowerFC reading) is a synthetic indicator of engine 'health'.

A bad engine is 60+

Mine came to 11-12 avg.

A new engine is supposed to be 20.

A well run in good running engine is 10.

30 - 40 might be a more well worn motor.

As it gets higher, the 'worse' condition the engine is (ie. the more likely you need a rebuild or the more it 'pings' metaphorically speaking).

Funny thing is that an engine that has forged internals will put out worser numbers.

This is a reading that the ECU (in its limited intelligence) gives. It is not 100% reliable.

T.

[Zahos]

But that still doesn't answer my question...

See the SAFC has a number that it spits out in:

settings -> Knk level

ans another on the monitors. The one on the monitors is relative to the one found in settings....

For example when I start the car cold, the reading is 40 (in settings), so I set the knock levels for 1650 and 3650 (that's all it lets you set) to 40.

Then, as the car warms, the number it shows for the current rmp grows to about 100, sometimes more.

The munber in the monitor section, is always around 20 on idle (when the car fully warms up), and about 9 when driving....

I dont know what the difference is between the 2.....

Does any1 know?????

DJ_L3THAL: I have attached a pic of the ecu as you look at it mounted in the side panel. the light blue (23) and light green(24) are the wires for the knock sensors. Connect it to 24 (cylinders 4-6) as I have read that they lean out first.....

[T0nyGTSt]

Think about this - does your engine run the same in every environment?

Run a bad load of fuel - the engine will run bad = higher knock number.

Run it on a cold morning and the motor rattles due to the cold = higher knock number.

If I warm the car up, kill the motor, reset the knock - the rating is like 1-5 which is almost unbelieveable.

T.

[Zahos]

All this I understand, but it does not explain the correlation between the 2 different readouts for knock...

The one in the setting menu, hangs around the 100 mark when idling, and increases as rev it out.

The one in the monitor section peaks at 20 on idle, and drops to 9 as I rev it out..

Which figure do I go by?

[Grim]

maybe the one in settings is the raw data value from the ecu but the one in monitor is the adjusted (true) readout.

[Zahos]

Yeah, thats what I am thinking (otherwise why would it be in the monitor section)

But obvioulsy it has some correlation with the values that can be set in the settings section. I wonder how this value would differ if the the setting were changed?

So then.... what should the two knock values for 1650rpm and 3650 rpm set to????

[Busky2k]

I got a SAFC II hooked up to my S14 SR20DET. I reckon the knock readout is completely haywire. The best way to check it is to go to the "sensor chk" and get a direct reading. I get around 50 when idling and it goes higher as revs rise/engine warms up.

I reckon the readout is complete shit as I can floor it at 3500 rpm or 2500 where knock would occur and it stays exactly the same, not even 1 unit count higher. Then I unplugged the det. sensor, and put a resistor on the harness and left it. And guess what. The readings were the same! WTF? How can it even get any readings if its not even hooked up? Sometimes it would show a value of 50 and then I swtich the car off. And it drops to 45. It should go to zero cos the engine is OFF!!

I cant figure it out either, so I disregard the knock sensor input. Hey btw, do you sometimes get trouble switching between File 1 and 2? I sometimes find switching between them CLEARS all my settings!!!!!!! Pisses me off.. Blah =(

The 2 maps/knock sensor reading is the reason i got the II over the original SAFC =(

[Zahos]

Nah, I haven't tuned the second file, so I haven't tried switching...

I might this weekend though, as I finally booked it in for a dyno tune...

Yeah that knock sensor readind pisses me of. It makes no sense.....

Did you figure out what the relationship is between the readind in the monitor section, and the reading in sensor chk?

I did 4 years of engineering maths at uni, and I cant figure the prick out!!!!

[Busky2k]

Go here to get the knock function working, but as I said before, its about as reliable as dogshit!!

http://www.prostreetonline.com/pso/pages/h....asp?sessionId=

Sensor Chk is the raw reading of the knock level. What you see during monitoring is any knock value that is HIGHER than what has been set in Knk Level. Ie so if the raw reading is 60 from the sensor, and the Knk Level been set to 50 (as background noise at that particular rpm), it'll report 10 to you!!

Read the link and it hopefully will clarify things. But still, i reckon the whole knock feature doesnt work. Might work properly with a separate knock unit from Apexi.

Let me know about switching maps too. Even just make two different files and switch between them while the car is off..

[SeriesIIGTST]

I have a similar thing on mine but much lower numbers.

Mine gets to about 10 on idle and reduces to 0-2 during driving. Is this indicative of a good engine (TOnyGTst?) or incorrect settings due to low numbers. I followed the instructions on that web page posted three times now with similar results.

[Zahos]

Hey Busky, thanks for the link.

OK, I am a little less confised, but I still don't fully undersatnd it.... I can't be bothered with it anymore though.

I dont think that it tells you what lever you have gone over the raw reading....

For example, my "acceptable" levers for the 2 rpm ranges specified are: 42 and 47 respectively. Sometimes the raw value has gone up to 130 when driving for more than 1 hour, but the readout in the monitor section is still only 9.

47 + 9 = 56 so that cant be right.

I guess we just stay tuned to that site for the next update...

[rev210]

The knock sensor is handy.

It learns the 0 point by the average of the two rpm ranges. The figures given are then taken as 'knock level' in the monitor section.

If done right the level of knock will stay around 0 for idle and low throttle, as this has been zero'd.

I have mine set such that I can use it in the 'graph mode' against rpm etc.

I find that a knock level upwards of 70 will correspond to a very light ping that gets worse, upto 190+ for a substancial ping. Setting the fuel and timing to a level where a max of 20ish is reached at the peak is what I aim at.

[Zahos]

So what have you set the knock level to be in those rpm ranges? Depending on what these are, it determines the value in the monitor section like you say.

For example, when I fist did it, the car was warm, and so those 2 values it bases the average on were 70 and 90 respectively. From that, my knock readout in the monitor was never over 7 on idle, and dropped to 1 when cruising / WOT.

Now I set them again when it was cold and they are in the low 40's, so I peak at 19 / 20 on idle, and drop to 7 - 9 on WOT.

How is everyone else's setup?

[rev210]

engine should be warm. Readings taken without any adjustment to the factory map.

[Zahos]

But that is what confuses me now....

If you take these readings while the engine is warm, your car could be knocking like crazy, but you set these knock levels at that time. Then in the monitor section, as that reading is relative the level you have adjusted, it would still show a low figure!?!?!?!?

So the knock level shown in the monitor section, is only relative to: how bad your car was knocking at the time you set it.

So how does this figure give you a true indication of knock? This was my argument to begin with....

It's giving me lots of headaches... I'm the type of person that doesn't just accept things, I need to know how it all works...

[Busky2k]

LOL told you man, its not reliable at all!!

I wound the timing way back as an experiment and it still showed knocking. WTF? And as i said b4, I disconnected the knock sensor once and it still said i was knocking.. heh.

=(

I'd just leave the settings at 70/90. Just when u boost it, make sure it doesnt go >150 (over the noise value) or some high figure like that!! Usually the ECU will wind back the timing if it senses knock anyway, so usually fat knocking wont occur in the first place unless the ECU cannot retard the timing any more. The SAFC might be confusing knock for engine noise at high RPM..

Im gonna take a look at Link's KnockLink. Looks good!!

[rev210]

a 'knock engine' as used to test RON figures for fuels will set you back the best part of $200k if you want an 'accurate' figure for knock. I'd suggest that the factory ecu does not allow the engine to "knock like crazy" under any circumstance (given factory timing and appropriate fuel). If your engine is 'knocking like crazy' expect it to die pretty soon.

The 'relative figure' as used by the factory ecu is good enough to tune with. Mine is fairly predictable and has served well as a tuning guide. The knock is best looked at on the graph trace Vs rpm and fuel correction. This way you can determine the relative 'stress point' of the engine's power band under load and adjust timing and fuel to suit.

I can quite easily remove any knock by decrease to timing and increase to fuel, the problem is in finding the balance for power.

[T0nyGTSt]

I got a 60 because I was pinging like crazy with my crap r33 AFM and bung fuel pump.

T.