KR explained

[Lex]

I have a lot of questions regarding KR and I wanted to clarify things a little about several nuances of KR that are NOT caused by detonation and the timing curve in the map.

1. Spool up KR. Here you will see a bit of KR (anything under 1.0 I just take as a "we've reached the efficient point" sign). This is common and not to worry you if it dies down like it does here and does not exceed 2.0. Remember the ECU drops KR in steps over a certain period of time and you can see this here and in all logs. If the KR is dropping it means no more knock is detected and the ECU is returning the timing to the base table. Why in this log? Look at your BATs - they are higher than in other logs.



2. High RPM KR that is a result of mechanical noise/shifting. Again the same log you will see that over 6K RPM there is a 0.7-1.0 or so of KR creeping in. This is a sign of mechanical noise but at 0.7 it's not something to really worry about. Then take a look at the 2.1 value there before it goes to 0. That is where you let off the throttle and the motor moved in the engine bay causing again mechanical noise. This is very common - a fast spike just as you shift or right when you let go of the throttle. This is not knock - just the engine moving around in the engine bay - don't worry about this. You can decrease the sensitivity of the sensor in the high RPM region. However if it is very high KR (2-3+), you're either indeed detonating or have a VERY noisy engine (see comment below)



If you see consistent high KR (5+ during WOT runs) and it is not due to timing or during shifting this is caused by other mechanical parts. Anything from a timing chain, to injector seals, to a bent rod. So keep an eye and diagnose this instead of trying to tune around it. Below is that turned out to be KR caused by a bent rod. As you can see it ramps right up to the max 5.95 and sits there regardless of timing (which drops into negative numbers).




3. Cold engine KR. When the car is not fully warmed up (even if the temperature gauge tells you it's fine) you may experience more KR than usual going up in the RPM range or under boost. This is because the engine internals have not reached operating temperature and expansion and are just noisier. Rule of thumb is to drive the car for at least 15 minutes before doing full WOT runs ... or to get an oil temperature gauge. Either way, if the car is cold, it's best to let it warm anyways before really getting on it so this KR serves as a friendly reminder.

[Stealth01]

I officially propose we change Lex's username to "Professor Lex" and make him the wheelchair-bound, bald leader of the "Lex-Men."

[DISIindahead]

@Lex my buddy just got back from getting his car tuned. He did like 20 runs with no knock and is now hitting 5.9. He says it does it all the time now. I told him to watch for what you stated. Hes going back in to get tuned again, so we'll see what happens.

[Lex]

Originally Posted by DISIindahead @Lex my buddy just got back from getting his car tuned. He did like 20 runs with no knock and is now hitting 5.9. He says it does it all the time now. I told him to watch for what you stated. Hes going back in to get tuned again, so we'll see what happens.

That's a classic sign of something mechanical rattling in the motor unless he filled it up with 87 fuel.

Originally Posted by Sid3wayS So I've got a question, What temp should the oil be at to be considered "warmed up"?

That is a very deep topic. If you have a gauge, consider the temperature you see after 20 minutes of normal driving warm. If you don't have a gauge, drive normally for the first 15-20 minutes without intentionally doing WOT pulls to redline.

[IshiKage]

good shit, Lex. I mean, The Professor. :bows:

[Spoolme]

fucking kr

[Sid3wayS]

So I've got a question, What temp should the oil be at to be considered "warmed up"?

[crazyp]

Originally Posted by Sid3wayS So I've got a question, What temp should the oil be at to be considered "warmed up"?

I have both a pressure and temp guage. not knowing how accurate the pressure guage is before it warms up, when my engine is first started cold pressure is around 80 psi, if I was to drive right away it maxes out my guage. once the temp guage is 180ish degrees then I see 15-20 psi at idle and 60 psi driving. coolant temp gets hotter faster so when it reaches 180 the oil is normally 150 degrees. I usually drive off for wot runs once the coolant is 180 at least which is measurable in a cobb ap

[rfinkle2]

Once my coolant temp reaches 175*f, I no longer get part throttle or wot knock.

(well, the type caused by low engine operating temp anyway).

[Boost Addict]

Great write up, this should definitely be man a sticky. A lot of people are always asking about these cases of KR.

[hank25]

Cruising knock has been driving my crazy! Car is great at WOT and thats what matters but god that can sure be annoying! ! I have seen it up to 8.1.

[rfinkle2]

@Raider...can we get a sticky?

[speed d3mon]

this is exactly the info i needed. thanks so much!

[atvfreek]

I agree on sticky as well. Nice write up Lex!

Tappin

[IshiKage]

s@Lex whats your theory on why it seems like 08.5 and 09 Speeds do no react well to FFS'ing?

[Lex]

Originally Posted by IshiKage s@Lex whats your theory on why it seems like 08.5 and 09 Speeds do no react well to FFS'ing?

I don't think it's just those cars. I think there is an issue with the FFS logic where the car does not return to commanded AFRs after a shift and I've seen it in MS6s as well.

[Stealth01]

And btw folks -- them be MY logs lol. So my noobiness has been turned around into a learning experience for many. YAY!

@Lex -- played with the 1.6 map a bit and had no KR over 1.4, even during a 0-60 pull. And what I did have fit both your categories above. Only took one log, so I'll send you more later in the week, when I'm awake enough to drive safely again.

[Raider]

Stuck...Ill reward op when I get a chance.

[Lex]

Updated OP with bent rod KR.

[Stealth01]

Originally Posted by Lex Updated OP with bent rod KR.

And thank GOD those logs are NOT mine. LOL.

[TRex]

so...you seem to explain everything but actual predetonation knock.....so what exactly does predetonation knock look like?

[PaulDiGi]

@hank25 I agree with that cruising kr being annoying as hell. Totally fine during WOT but I consistently see 6.0 until the slightest load.
timing chain issue? or nothing to worry about like I have heard/read a million times.

[TriO]

Originally Posted by PaulDiGi @hank25 I agree with that cruising kr being annoying as hell. Totally fine during WOT but I consistently see 6.0 until the slightest load. timing chain issue? or nothing to worry about like I have heard/read a million times.

+1 same thing for me

[BigJimMs3]

Ahhhh yes the good olll fucking cruising then look down at my AP and see 4.3kr for no god damn reason KR lol.....

[atvfreek]

Here is a log of some "real knock". You can see the kr, and then as it starts to put timing back in, it pulls more. Sometimes you will see this if you fill up at a shitty gas station or driving real hard when the tune is pretty aggresive. This happened to be after a hard shift. The kr is less than 2, so it's well within the pcm's capability of pulling timing.

Sorry for just the log and no pic.

[rghispanic88]

awesome thread

[uncorked11]

@Lex Thank you for spelling this out clearly.

[bigriver]

Originally Posted by atvfreek Here is a log of some "real knock". You can see the kr, and then as it starts to put timing back in, it pulls more. Sometimes you will see this if you fill up at a shitty gas station or driving real hard when the tune is pretty aggresive. This happened to be after a hard shift. The kr is less than 2, so it's well within the pcm's capability of pulling timing. Sorry for just the log and no pic.

Here you go. Hope this posts okay. [shit, pic fail] Have to post from my home computer.

[atvfreek]

Originally Posted by atvfreek Here is a log of some "real knock". You can see the kr, and then as it starts to put timing back in, it pulls more. Sometimes you will see this if you fill up at a shitty gas station or driving real hard when the tune is pretty aggresive. This happened to be after a hard shift. The kr is less than 2, so it's well within the pcm's capability of pulling timing. Sorry for just the log and no pic.

Originally Posted by bigriver Here you go. Hope this posts okay. [shit, pic fail] Have to post from my home computer.

Just wanted to add to this a little. This kr only happened on one run out of a bunch with this map, so I left the map as is for the tune and he still hasn't had another run like that.

Also if you happen to fill up at a mom and pops gas station, and start getting kr that you haven't been getting. Just ride out that tank easy until you can refill at a known good station.

[p057]

any familiar characteristics of bent-rod knock?

or does it just fall under the "engine noises" category?


Awesome writeup that puts a little more mind at ease. Thanks.

[rfinkle2]

Originally Posted by p057 any familiar characteristics of bent-rod knock? or does it just fall under the "engine noises" category? Awesome writeup that puts a little more mind at ease. Thanks.

Most people get a vibration through the clutch before catching a log that shows knocking from a bent rod.

[Lex]

Originally Posted by rfinkle2 Most people get a vibration through the clutch before catching a log that shows knocking from a bent rod.

The one I posted didn't. Not that he could tell at least. Car ran like this for 2 weeks before venting #4 in front of the mall.

[dougefresh_]

Excellent write up!

[TiGraySpeed6]

excellent info lex, thanks!

[Domino81]

Subbed.

[G26]

I'd say about 75% of the time, i get some kr less than one on my logs, usually right after spool at max boost, and it drops it in steps.

[skiptowncat]

Any thoughts on KR in a particular gear, I'm getting anywhere between 2-4KR @~4.5k but only in 5th gear@ WOT??

@Lex @rfinkle2

[rfinkle2]

Originally Posted by skiptowncat Any thoughts on KR in a particular gear, I'm getting anywhere between 2-4KR @~4.5k but only in 5th gear@ WOT?? @Lex @rfinkle2

Lex is the expert, but I'd have to think that you are seeing different load values for longer durations of time in 5th gear.

[skiptowncat]

Originally Posted by rfinkle2 Lex is the expert, but I'd have to think that you are seeing different load values for longer durations of time in 5th gear.

I think I had already figured it out. Recently changed the open loop overload timing to match my normal table (following what I saw in a ots map) For some reason in 5th I seem to be hitting over my target which I'm guessing is why this is happening. I had advanced the normal table quite a bit previously. Just running in a new revision now, I'll let you know how it goes.

[Lex]

Originally Posted by skiptowncat Any thoughts on KR in a particular gear, I'm getting anywhere between 2-4KR @~4.5k but only in 5th gear@ WOT?? @Lex @rfinkle2

In any car you will see engine load go up as you go up in gear. The resistance to acceleration is higher so the engine will work harder and for longer. This increases the components that generate knock and these are cylinder pressure, temperature, and boost. As a rule of thumb, I look at mostly 4th gear when tuning because it will expose KR more readily than 3rd and running 5th to redline gets dicey in most areas.