knock retard
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- Start date
With this car, yes.
I've seen anywhere from 0.4 to 7.5.
I think we'll discover the secrets of the Bermuda Triangle before we learn why this car knocks so much. Some say the sensor is simply detecting a condition for potential knock and retards timing to prevent it before it happens.
I've seen anywhere from 0.4 to 7.5.
I think we'll discover the secrets of the Bermuda Triangle before we learn why this car knocks so much. Some say the sensor is simply detecting a condition for potential knock and retards timing to prevent it before it happens.
The cumbustion charge of this car is very hot. It's engineered to run 15.6 lbs of boost @ 9.5:1 compression ratio with 91 octane gas, but the boost spikes (dashhawk logs it going as high as 18 lb spikes) send it into KR territory.
I had a mechanicky type person look at the dashhawk logs and he was impressed by how this car stradles the edge of perfect tuning for what it is. 0.2 - 0.7 spark retards are like nothing he says.
Thats why this thing runs so rich; it shoots extra gas in there not for combustion, but to keep it cool. I don't think people take that into account when they start frowning at their AF mixtures.
A turbo with better thermal efficiency or anything else that will cool the compressed intake charge (FMIC?) would help with knock I would think. Bone stock the car is stradling just enough advance for how it is out of the factory.
Since I don't own one, I don't know, but I would imagine all high boost hot hatchbacks run into the same KR issues. I've just never really persued the dashhawk logs of an SRT4 or Chevy SS model. I think I looked up a Saturn Sky Redline ecotec DISI datalog once and it was hitting 1-4 spark ret during it's boost spikes too.
I had a mechanicky type person look at the dashhawk logs and he was impressed by how this car stradles the edge of perfect tuning for what it is. 0.2 - 0.7 spark retards are like nothing he says.
Thats why this thing runs so rich; it shoots extra gas in there not for combustion, but to keep it cool. I don't think people take that into account when they start frowning at their AF mixtures.
A turbo with better thermal efficiency or anything else that will cool the compressed intake charge (FMIC?) would help with knock I would think. Bone stock the car is stradling just enough advance for how it is out of the factory.
Since I don't own one, I don't know, but I would imagine all high boost hot hatchbacks run into the same KR issues. I've just never really persued the dashhawk logs of an SRT4 or Chevy SS model. I think I looked up a Saturn Sky Redline ecotec DISI datalog once and it was hitting 1-4 spark ret during it's boost spikes too.
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I got ******* 8.1 this morning. It was early in my commute, and I accidentally reset the ECU 30 miles ago (left lights on).
My LTFT's are still s*** and my STFT's jumped up to +25 for a few brief moments.
Granted, it was pretty cold this morning for where I live.
My LTFT's are still s*** and my STFT's jumped up to +25 for a few brief moments.
Granted, it was pretty cold this morning for where I live.
phantom6294
Member
First... no knock is the best knock. But as already mentioned, getting readings of KR on the MS3 and MS6 is pretty common.
I've personally found there are three 'types' of knock retard (KR) -- in other words, I get KR readings on my DashHawk in three different scenarios:
1) KR at WOT
3) Very short blip of KR upon lifting off the throttle after accelerating in boost -- normally in higher gears but not always
3) Sustained KR readings while cruising at light load / light throttle while being between 3-4k RPM -- normally in higher gears but not always
So, the first, KR at WOT should not be taken lightly. A KR reading of under 1 is probably okay, but if you consistently get higher KR readings while at WOT then you need to take it seriously.
The second form can probably be ignored. If it is real knock, well, you've just taken your foot of the gas and my theory would be the engine is rapidly ramping up the spark advance to account for the sudden drop in load and perhaps the conditions exist for a split second for a knock condition to occur but quickly go away.
The third seems to be the situation that is most prevalent and what is confusing the MS3 on the whole. I've been doing a lot thinking, reading, data logging, more thinking, and more reading, and more data logging. I've come up with a theory. Someone had mentioned that the ECU 'learns' around knock retard. Lately, when I am cruising and I get a knock retard alert on my DashHawk, I purposely do NOT lift the throttle. What I have noticed is that normally the knock retard is slowly 'aged out' or decays over time. In other words, if I get a reading of KR of 6, it will slowly work its way back to 0.
Take a look at this log from a few days ago; it has a long sustained KR reading going as high as about 6. At one point, I had a KR reading of over 5 for about 10 seconds.
Specifically, look at the relation of KR and Spark Advance -- when the KR jumps up, the spark advance briefly goes to 20 but settles at about 28. Then, as KR decays the spark advance slowly increases until it seems the spark advance is too much and the KR reading jumps back up and spark advance is retarded.
So, it would seem a reading of KR does not necessarily mean the car is knocking. Rather, the initial reading of KR would indicate a possible knock condition but after that, not necessarily. The reason is that if the engine were STILL knocking after an initial retarding of the spark timing, wouldn't the ECU continue to pull timing and the KR reading continue to go up until knock was eliminated? For example, in my log, if the KR were a reading of actual and, more importantly, continued knock, why the heck wouldn't the timing be dropping through the floor with the ECU in a panic attack to get the knock under control????
It seems more that the ECU is alerted of a knock condition, it retards the timing, and then begins to work back to the 'base' timing in the map. It's as if the ECU uses KR as a spark timing version of the fuel trims -- a short term (maybe long term?) adjustment to the spark advance. This jives with my experience -- lately I've ignored the KR alerts while cruising (for science, and since my car is bone stock... if it blows, new engine for me!) and every time the KR works back to zero eventually. Also, many people report that they will lift the throttle when they see the KR reading but as soon as they get back on the throttle, the KR returns. This would potentially imply that the ECU learns/remembers the KR for a certain engine condition. So, when you get back on the throttle and return to the previous engine condition, the ECU once again is using the KR to adjust spark advance for those engine conditions. The question would be... how long does the ECU store the KR readings for given engine conditions. If it is for a significant time, then it is possible when you return to a certain engine condition (minutes, hours, days? later), the KR reading suddenly goes up without any actual knock event.
Now, this doesn't actually answer what causes the initial knock in the first place... but, I have a theory for that as well -- at least for the random knock in the 3-4k RPM range while cruising (light load / throttle). Well, in those conditions, the engine is going for optimal fuel economy and optimal burn for the lowest emissions. Well, in such conditions, the timing has to be pretty advanced to ensure optimal and complete burn... maybe the default timing maps are a bit aggressive?
I've personally found there are three 'types' of knock retard (KR) -- in other words, I get KR readings on my DashHawk in three different scenarios:
1) KR at WOT
3) Very short blip of KR upon lifting off the throttle after accelerating in boost -- normally in higher gears but not always
3) Sustained KR readings while cruising at light load / light throttle while being between 3-4k RPM -- normally in higher gears but not always
So, the first, KR at WOT should not be taken lightly. A KR reading of under 1 is probably okay, but if you consistently get higher KR readings while at WOT then you need to take it seriously.
The second form can probably be ignored. If it is real knock, well, you've just taken your foot of the gas and my theory would be the engine is rapidly ramping up the spark advance to account for the sudden drop in load and perhaps the conditions exist for a split second for a knock condition to occur but quickly go away.
The third seems to be the situation that is most prevalent and what is confusing the MS3 on the whole. I've been doing a lot thinking, reading, data logging, more thinking, and more reading, and more data logging. I've come up with a theory. Someone had mentioned that the ECU 'learns' around knock retard. Lately, when I am cruising and I get a knock retard alert on my DashHawk, I purposely do NOT lift the throttle. What I have noticed is that normally the knock retard is slowly 'aged out' or decays over time. In other words, if I get a reading of KR of 6, it will slowly work its way back to 0.
Take a look at this log from a few days ago; it has a long sustained KR reading going as high as about 6. At one point, I had a KR reading of over 5 for about 10 seconds.
Specifically, look at the relation of KR and Spark Advance -- when the KR jumps up, the spark advance briefly goes to 20 but settles at about 28. Then, as KR decays the spark advance slowly increases until it seems the spark advance is too much and the KR reading jumps back up and spark advance is retarded.
So, it would seem a reading of KR does not necessarily mean the car is knocking. Rather, the initial reading of KR would indicate a possible knock condition but after that, not necessarily. The reason is that if the engine were STILL knocking after an initial retarding of the spark timing, wouldn't the ECU continue to pull timing and the KR reading continue to go up until knock was eliminated? For example, in my log, if the KR were a reading of actual and, more importantly, continued knock, why the heck wouldn't the timing be dropping through the floor with the ECU in a panic attack to get the knock under control????
It seems more that the ECU is alerted of a knock condition, it retards the timing, and then begins to work back to the 'base' timing in the map. It's as if the ECU uses KR as a spark timing version of the fuel trims -- a short term (maybe long term?) adjustment to the spark advance. This jives with my experience -- lately I've ignored the KR alerts while cruising (for science, and since my car is bone stock... if it blows, new engine for me!) and every time the KR works back to zero eventually. Also, many people report that they will lift the throttle when they see the KR reading but as soon as they get back on the throttle, the KR returns. This would potentially imply that the ECU learns/remembers the KR for a certain engine condition. So, when you get back on the throttle and return to the previous engine condition, the ECU once again is using the KR to adjust spark advance for those engine conditions. The question would be... how long does the ECU store the KR readings for given engine conditions. If it is for a significant time, then it is possible when you return to a certain engine condition (minutes, hours, days? later), the KR reading suddenly goes up without any actual knock event.
Now, this doesn't actually answer what causes the initial knock in the first place... but, I have a theory for that as well -- at least for the random knock in the 3-4k RPM range while cruising (light load / throttle). Well, in those conditions, the engine is going for optimal fuel economy and optimal burn for the lowest emissions. Well, in such conditions, the timing has to be pretty advanced to ensure optimal and complete burn... maybe the default timing maps are a bit aggressive?
serialtoon
Member
- :
- 2008 Mazdaspeed 3
Wow Phantom! Way to go with the theory man. I was just about to post a thread about my morning commute and how a knock of 2.4 was read on the third scenario you posted.
Put simply. All cars have KR under normal driving conditions. This is just a part of normal engine operations. Put the DH on any other car and you will see this is the case. Cruse speed KR is nothing to worry about and is simply the ECU adjusting to normal driving conditions. Timing is advance till KR is seen then adjusted back. No worries, all is good. This is why you typically see KR under normal conditions in the start of your drive after the car warms up (at least that is how I see it) then after a few KR notices you don't usually see it again for that drive. I see this every day typically on my way too and from work (I have my DH set to alert at 2degs of KR).
What you don't want is KR at WOT. WOT KR is bad specially if you hear audible pinging. Now with that said, it is not uncommon to see KR at WOT on stock MS3's. There are many posts about this. There were a lot of theories about it (sensitive KR Sensor, 91Oct VRS 93Oct as an example) and some believe that its just normal and some believe it is not. The moral of the story is some people see 6degs of KR stock and some don't. It's a crap shoot.
I personally had upwards of 6degs of KR on my car at WOT in stock or semi-stock trim. I was not too worried about it. Now that I have an AP I don't have any KR at WOT and I'm happy.
So long story short, if you have KR during normal driving it is NOTHING to worry about. KR at WOT is something to worry about but keep in mind that on our cars in stock trim it is normal.....so take that as you will.
As always, it's a good idea to let off if you see KR and most certainly if you hear audible pinging.
What you don't want is KR at WOT. WOT KR is bad specially if you hear audible pinging. Now with that said, it is not uncommon to see KR at WOT on stock MS3's. There are many posts about this. There were a lot of theories about it (sensitive KR Sensor, 91Oct VRS 93Oct as an example) and some believe that its just normal and some believe it is not. The moral of the story is some people see 6degs of KR stock and some don't. It's a crap shoot.
I personally had upwards of 6degs of KR on my car at WOT in stock or semi-stock trim. I was not too worried about it. Now that I have an AP I don't have any KR at WOT and I'm happy.
So long story short, if you have KR during normal driving it is NOTHING to worry about. KR at WOT is something to worry about but keep in mind that on our cars in stock trim it is normal.....so take that as you will.
As always, it's a good idea to let off if you see KR and most certainly if you hear audible pinging.
- :
- 2001 Mazda MP3
i've been getting high KR in 5th gear about 60 MPHs, I have a warning set at 0.1 and another at 1.0, and under WOT i hardly EVER see KR, but cruzing i've seen as high as 7. or so,
That is nothing to worry about. I would change that 0.1 KR notice to at least 2KR so you don't see it that often. I have mine set at 2KR mainly for WOT purposes as I'm not worried about less that 2KR at WOT. I have it set for 2KR, 4KR and 6KR. This way if I see any warning at WOT I let off.
- :
- 2001 Mazda MP3
http://www.mazdas247.com/forum/showthread.php?t=123733000
hey guys, i'm trying to get a sticky for all dashhawk stuff related, as far as what you have warnings set at, and Logs that you want to post
hey guys, i'm trying to get a sticky for all dashhawk stuff related, as far as what you have warnings set at, and Logs that you want to post
phantom, KR job is to reduce knock, as we don't really understand the whole 3k-4k rpm knock reason yet, the KR job is to reduce knock and that is why you are seeing a reduction of KR as you continue driving. I don't think mazda, or any company for that matter, would set up an ECU to learn from knock, as KR means that the knock has already happened and the "potential" damage has already happend, so the KR comes into affect to reduce the chance of further "potential" damage. Lift up the gas at any knock, do not continue to cruise or WOT if you see knock great that 2-3.
phantom6294
Member
I am quite confident you're wrong in this respect. Continued advance of timing, is utterly and completely pointless and I don't believe ECUs are programmed to do so; they have a programmed map for spark advance based on engine operating conditions. Since nothing in the world is perfect (MAF sensor, timing map, fuel quality, etc, etc) the knock sensor exist as a just in case safety feature in case knock happens. If ECUs, while cruising, advanced timing until the onset of knock, then we would ALL see KR while cruising and would see go back and forth, back and forth... but, by all means, please go cruise around at a constant speed on a flat surface and log spark advance showing it continually increasing until the onset of knock -- I'd love to see that log, I'll be waiting.
Well... thank you Captain Obvious. More accurately, though, KR is used to retard the timing which is done to reduce (or better, eliminate) knock.
Hey, I said it was a theory. If you have a better explanation as to why the KR is slowly decayed and spark advanced is correspondingly added back, trying to return to the programmed timing map... then by all means, share. I use the term 'learn' in a very loose way. Want to use another verb, then by all means share. I personally think the comparison to Short Term Fuel Trims is a fair one. The ECU uses the STFT, based on the AFR, to adjust the fuel amount... the ECU uses KR, based on the knock sensor, to adjust the spark advance.
My point in voicing the theory was to dispel the idea that a reading of knock retard indicated actual and continued knock, which is most likely not the case. A reading of KR merely indicates the knock sensor has detected an instance of knock, and the ECU is currently in a mode where it is retarding the timing from the timing map. I've seen numerous people see a log with sustained KR freak out and make comments like 'your engine was knocking like crazy!!!' Well, most likely not... if the engine continued to knock... it would only make sense that ECU would continue to pull timing until knock was under control.
it wasn't anything personal, I just don't want people thinking that should continue cruising or flooring it if they have knock. It just kind of seemed like you were incouraging that way. My main point is that if there is not detected, just take the foot off the gas pedal.
Theories are good, I personally have a theory that since we have all this spike in power at around 3k-4k rpms, that something in the stock tunning itself is causing the knock. Alot of people can tune this out with an aftermarket tuner, so that is why I believe this.
Theories are good, I personally have a theory that since we have all this spike in power at around 3k-4k rpms, that something in the stock tunning itself is causing the knock. Alot of people can tune this out with an aftermarket tuner, so that is why I believe this.
My point is KR at cruse is NORMAL and happens on all cars. It's just part of the normal PCM process of maintaining AFR's and other thresholds. My timing example may very well be worded wrong and I probably should not have worded it that way, but I did for brevity sake and nothing more. The POINT was that KR at normal cruise is normal and nothing to be concerned about as all cars will experience KR at times during normal driving due to Load, timing, gear shifts etc......it's normal.
Conditions change all the time in normal cruise. The ECU is programmed to pull timing for actual KR and also to anticipate possible KR situations. That is why you can be cruising just fine and go up a little hill (like an overpass) and have to give a little more gas to maintain speed and all of a sudden you see 2KR. You're not getting actual pre or det, but the PCM is adjusting due to load and maybe your timing was more aggressive for the current condition. Thus is pulled a little timing and re-adjusted. This is what I meant by my timing statement above.
There are simply a ton of theories on the internet about KR under normal driving. Do a quick search and you will see that we're not the only cars with KR at normal driving. The end conclusion is that KR at normal driving is no issue.
What your DH logged is what is called False KR. KR is when the KR starts and continues to build. False KR is usually a quick spike followed by an immediate decline to a lower number or zero which is the exact opposite of what true KR looks like in a log.
Anyway, I hope I'm a little more clear this time in what I meant. KR is simply normal during normal driving conditions and is not limited to just our cars.
Speed3Rookie
Member
So...what do the ppl that are not stcok nor have a dh do as this same kr is ocurring?
In that case, let off if you hear pinging
That's all you can do without a KR sensor. However, you will feel the timing being cut as a little stutter.Here is a quick down and dirty explanation of KR.
https://www.zzperformance.com/grand_prix/articles1.php?id=20
https://www.zzperformance.com/grand_prix/articles1.php?id=20
i usually only get random knock when my boost air temps are above about 110+ and i have a FMIC. that doesn't mean its doing its just because in reality it has nothing to do with when you are cruising since that air won't cool as much as boosted air. whenever i get into boost it does drop quickly though so its doing its job. the problem is our intake manifolds seem to heat up quickly from the engine and basically act like an oven for the air coming in.
