knock what is a sfe knock and what would be a bad knock?

[GstRacer]

look i just got my car tuned and dynoed with my afc2 but i'm trying to figure out what is a bad knock and what is good knock to set the warning on the afc2 to tell me something going wrong so please help like give me a number thats not good to see so i can set it on the warning thanks i also got 257HP at the front wheels and 227 tq at 15 psi power baby

 

[terminaltsi]

bad knock is anything that pulls timing. there is a specific range some of the guys here know, i forgot what it is, but just look at yourlogger. when you have too much knock, you won't have much timing.

 

[GstRacer]

i don't have a logger to look at thats why i'm asking for some numbers

 

[CanadianTSi]

The S-AFC 2 cannot read knock on 2g's even though it says it can.

Get a logger and look at your timing curve, if it isn't a smooth increase then you are probably knocking whenever you see a decrease in timing.

 

[philipkrotch]

any knock above 8-10 i believe will pull timing. i have mine tuned to about 5 counts of knock at full boost at WOT and it runs great.

 

[BrnOutKing]

2G knock Counts are different then 1G Knock counts. So don't mix them up.

On a 2G DSM for every 1.5 counts of Knock it pulls 1 Degree of timing. Personally I Tune for "0" counts of knock on my 2G. Some people are ok with running 2-3 counts. (if I see 2-3 counts I take notice but I don't get nervous. However 3.5+ counts and I'm off the gas as quickly as I can. But that's just me. 5+ and your looking at possibly blowing your motor.


As for a 1G - I believe under 30 counts is normal/acceptable. (ie: "10" on a 1G is just like "1" count for a 2G)

 

[LandoAWD]

2G knock Counts are different then 1G Knock counts. So don't mix them up.

On a 2G DSM for every 1.5 counts of Knock it pulls 1 Degree of timing. Personally I Tune for "0" counts of knock on my 2G. Some people are ok with running 2-3 counts. (if I see 2-3 counts I take notice but I don't get nervous. However 3.5+ counts and I'm off the gas as quickly as I can. But that's just me. 5+ and your looking at possibly blowing your motor.


As for a 1G - I believe under 30 counts is normal/acceptable. (ie: "10" on a 1G is just like "1" count for a 2G)

Timing is pulled WAAAAAY before 30 counts.

In general, no knock is good knock.

 

[kpt4321]

2G knock Counts are different then 1G Knock counts. So don't mix them up.

On a 2G DSM for every 1.5 counts of Knock it pulls 1 Degree of timing. Personally I Tune for "0" counts of knock on my 2G. Some people are ok with running 2-3 counts. (if I see 2-3 counts I take notice but I don't get nervous. However 3.5+ counts and I'm off the gas as quickly as I can. But that's just me. 5+ and your looking at possibly blowing your motor.


As for a 1G - I believe under 30 counts is normal/acceptable. (ie: "10" on a 1G is just like "1" count for a 2G)

This is way wrong, a whole bunch of times.

Both 1g's and 2g's will retard one degree of timing for approximately 3 knock sum. The actual factor for a 2g is like 90/255, which is 0.35. I think that 1g's are the same or very close.

5 counts of knock will not blow your motor, probably never. When you start getting up in the 20-30 range, you may be doing permanent damage, but in very small doses.

I like to tune all the cars I touch to under 4 counts of knock, or what comes to to about 1 degree of knock retard maximum.

 

[G9S1X]

On a 1G this is what happens.

0-3 Knock timing will advance
3-7 Knock timing stays the same
7+ Knock timing will retard. Higher the knock the higher timing will retard.

 

[kpt4321]

On a 1G this is what happens.

0-3 Knock timing will advance
3-7 Knock timing stays the same
7+ Knock timing will retard. Higher the knock the higher timing will retard.

That might not be true, and I personally believe that it is not. That's what it "looks" like on the logger, but if you look at the actual timing map, your knock sum, and your reported timing, you will find that you tend to get one degree of timing pulled for approximately 3 knock sum.

If 2g's do it that way, why wouldn't 1g's? A lot of the ECU architecture is the same.

 

[Sotarts]

So who is right and what number I should stay away from?

 

[kpt4321]

I'm right. Knock sum divided by three is very close to the true knock retard.

I start to think about lifting around 5 degrees of knock retard, which is about 15 knock sum. However, you probably won't damage your engine even there.

Tune for as little knock sum as possible.

 

[Sotarts]

I think I'll just tune for zero knock then. And if I end up with 1-2-3 here and there at WOT, at the end of RPM line, I won't freak. It's not like we drive WOT 100% of the time.

 

[kpt4321]

Yup. Just tune so that the car is on the edge of knocking, so that you see a couple knock sum here and there periodically.

 

[BIGGSIE]

I use the "alarm" feature on MMCD and set it to beep at me anytime it hit's 6 knock counts. I think it works pretty good for tuning.

 

[Sotarts]

I use the "alarm" feature on MMCD and set it to beep at me anytime it hit's 6 knock counts. I think it works pretty good for tuning.

I've tried that with a logger and have discovered that while on the move, if you have "alarm/trigger" set as that, logging happens one or even two seconds (sometimes three) later after the fact--could be a little too late to see what's going on across the board.

 

[Sotarts]

One question. Sorry, I ddon't have time to search (I have to leave)--and we have to tune my buddy's '97 TSi with freshly installed Evo 16g, with 550's and 255lph HP pump--very soon.

How can we monitor knock on 2g cars? 2g cars don't have knock sensors as far as I know. I appreciate any help. Thanks.

 

[G9S1X]

just watch where your timing gets pulled, which ever rpm range that timing is being pulled you have knock.

 

[Sotarts]

just watch where your timing gets pulled, which ever rpm range that timing is being pulled you have knock.

That's no help at all. Am I supposed to pull numbers out of thin air?

 

[rarson]

If 2g's do it that way, why wouldn't 1g's? A lot of the ECU architecture is the same.

I don't think the 1g does knock retard at all like the 2g. First off, the 1g knock sensor is way less sensitive than the 2g. Secondly, the 2g doesn't keep a sum of raw knock count like the 1g does. There's a "backround" that the ECU uses to determine knock above that level. You're right, 3 occurences of what the ECU regards as knock results in a degree of knock retard. But I think you're looking at 2 different things when comparing instances of knock between a 1g and 2g.

I'm not saying you're wrong, I'm just saying I think it's a bit different. I've never datalogged with a 1g so I can't really comment on that.

 

[RipperXX]

Damn it I need to get the logger software!

My EGR vavle is stuck open, and I fear it's knocking something horrible. (And I have driven it for a LONG time like this, unknowingly)