There's a general sentiment around here that says the factory knock sensor, for all practical purposes, does nothing. But do we just not understand it? I have a log here of a WOT pull on an Rx-8 with a Greddy kit and an Emanage. It was originally posted in my thread about how the Emanage default timing maps suck.

http://www.rx8club.com/attachment.php?attachmentid=157509&stc=1&d=1276031154

This appears to be knock retard, especially since the owner reported a hesitation here. The EMU is reporting rediculously low timing advance values. Those two little dips are on the leading but then the trailing remains flat until the engine comes off throttle. I don't know if that means the spark was cut completely on the trailing or what. One thing to notice here is that the retard on the leading happened extremely fast (about .02 seconds), if the Emanage logger is to be trusted. It may not be possible to see this on an AP or other logger.

The sample rate for the Emanage Ultimate logger appears to be much higher than what direct PCM interfaces (AP etc) are capable of, approximately 50 samples per second. This is because the EMU logs sensors directly instead of going by what the PCM reports, which of course also has its disadvantages.

Here is another log of what appears to be detonation and knock retard:

http://www.rx8club.com/attachment.php?attachmentid=158536&stc=1&d=1277939537

5500 rpm on this log too. Boost is about 5.5psi, leading timing was 27 degrees with 15 degrees split until the knock occurs. The leading timing retards suddenly and recovers, but the trailing appears to be retarded or cut completely until the throttle closes.

So does anybody have any logs showing knock retard? The questions I wonder are:

1) Does the Rx-8 PCM have some kind of long term knock control strategy like so many other manufacturers have? It may exist and we just don't understand it.

2) Is there some kind of filtering or noise baseline calculated by the PCM? On certain Evo applications you can actually change this logic to affect the sensitivity of the knock control

3) In the AP helpfile I have (I don't have an Rx-8 AP) it lists a "Knock Retard - Base" table but with no description. Anybody have a screenshot of it?

4) There are timing decrement tables listed in the AP, to specify how many degrees of timing are pulled per knock event. But in the logs I've shown above the timing appears to be pulled very quickly and very drastically. I wonder when those decrement tables are actually used and how a knock event is actually determined.

This again makes me wonder if there are more than one knock control strategies that we don't really understand.

Max retard is -10 degrees....those logs look suspiciously like ignition dropout...not knock retard

AP has 10 tables for knock control

Base table...-10 below 5KRPM
Gear specific tables 1-2 and 3-4 -1degree decrements Gear 5-6 -2.5 deg decrements

MAX rpm 7000rpm
Min ECT 50 degrees

did you solve this issue?
was it a bad knock sensor?
actual detonation?

or some odd ignition issue?

I seem to be having the same issue, I was finally able to log the event, but its basically standing on the throttle 5900rpms and stays there, my logs show the leading pulling timing
about 5psi, too, after releasing the throttle the car goes back to normal

I can cruise in same gear at 6500rpms no problems.

Yes this is a thread revival, but its better then starting a new one

are you sure? This can be caused by other engine load conditions like air intake temp etc, nobody I know of has actually seen it work, the Cobb will supposedly read it directly but always shows zero change

I dont know if I want to log it again to see. Intake temps are pretty steady 2nd gear is 59 and drops to 49, random timing pull. 3rd gear is 43 - 41, strong pull in one sec it pulls from 11 down to 5 degrees. Stock o2 is pegged 10.95, auxwo2 (in catless midepipe) reads 11.9 - 11.6.
So real knock or?

Looking at logs again. Car has to be at 50% load before knock senser can work (atr setting) right past 50% load on my logs timing starts getting pulled and messed with

The AP will specifically log knock retard. There is no need to guess.

I made some adjustments to my tune (Knock section). when weather permits I should be able to make some more logs, with my quick preliminary run, and some sliding in ice there didn't seem to be any knock sensor detection to pull timing

did you have knock before? If you did you never stated so.


.

Did I have physical detonation or knock? I don't think so, never heard any, never any "jerking", nothing in the logs suggested I did.

However

Did the knock senor detect "something" and pull timing? yes

Did the knock senor detect "something" and pull timing? yes

Did you see this as a change in timing or an actual knock retard value?
If it is only the former, than the knock sensor had nothing to do with it.

It is likely that you have bad IAT values being reported sporadically.

Did the knock senor detect "something" and pull timing? yes

Is that your guess or did you actually go back and specifically log knock retard using the AP function as was previously discussed? Again, if you did it was never stated.


http://www.rx8club.com/attachment.php?attachmentid=179732&stc=1&d=1324197547

I was able to take some logs today its pretty cold 34-36 degree intake temps.
knock senser never activated
Timing was being pulled....

how does intake temps affect timing?

rpm Time auxafr oemwot
6461 0 5 0 11.25 10.95
6595 0 5.5 0 11.39 10.95

looks like its starts preparing for the apv? is there a timing retard for apv on cold intake temps?


5583 0 11
5742 0 8.5
5910 0 8.5
6041 0 9
6193 0 9
6193 0 9
6338 0 7
6461 0 5
6595 0 5.5
6786 0 7
6906 0 10

I haven't experienced this issue, but sounds to me like it may be pulling timing due to a high RPM delta. How do you have those tables set?

AFAIK, intake air temperatures only affect timing by changing load.

I don't see a High RPM delta, do you have another name?

there is Leading rpm delta A & B, and Trailing RPM delta A & B. both of which have not been changed from Stock

Actually those are the ones I'm referring to. As RPM changes quickly, these tables may come into play, though for my car I only really see it at idle and going off throttle.

I don't really know how to adjust these tables properly, and I wonder if there isn't something wrong with how they are set up in ATR. For example, if I use the Mazda scaling, the values come out like this:
http://www.rx8club.com/attachment.php?attachmentid=179747&stc=1&d=1324270431

Versus this in ATR:
http://www.rx8club.com/attachment.php?attachmentid=179748&stc=1&d=1324270431

are you saying that my rpms are climbing so fast that these tables are reducing timing?

I have heard (http://www.rx8club.com/showpost.php?p=3998236&postcount=6) that this is possible.

so the question is, now that I am forced induction should I leave it alone or change it?

Did you see this as a change in timing or an actual knock retard value?
If it is only the former, than the knock sensor had nothing to do with it.

It is likely that you have bad IAT values being reported sporadically.

wouldn't that show up in the logs, its a steady 36 degrees, then 34 degrees. and it seems to be happening in a predictable fashion

I have heard (http://www.rx8club.com/showpost.php?p=3998236&postcount=6) that this is possible.

You heard? lol

Was I really being that vague?

Sometimes you have to wonder why you even bother ...

.

http://www.rx8club.com/showthread.php?p=3427930 Interesting thread with more hints

http://www.rx8club.com/showpost.php?p=4048203&postcount=138 obviously my issue

http://www.rx8club.com/showpost.php?p=3427570&postcount=9. yet again

the key search phrase was "rpm delta"

thanks oltmann,

now onto further investigations.....

You heard? lol

Was I really being that vague?

:bowdown:

Anyhow, I'm reasonably convinced that this table is screwed up in ATR. If you want zero timing retard, enter -64. If you want advance, add desired advance to -64. If you want retard, just enter the value. 32 degrees in either direction is the max.

I think that the A tables are for when the car is in gear, and the B tables are for neutral, but I haven't checked yet.

So, it must be there for a reason, should I leave it or have it pull less timing?

For the positive RPM delta values, I think it is there to reduce detonation during transition from cruise to acceleration.

At light loads - as are used in normal everyday cruise conditions - an ignition advance of 40 degrees or more will improve responsiveness and economy. This advance can be used successfully on many engines - even those with an 11:1 compression ratio, if they are being run on high octane fuel. One factor limiting the cruise ignition advance that can be used is the maximum ignition timing attack rate provided by the ECU - that is, how fast the timing can change. If very advanced timing is being used with light loads and the attack rate is not high, there may be slight detonation when the engine load suddenly increases. link (http://autospeed.com/cms/title_Getting-the-Ignition-Timing-Right/A_109132/article.html)

OTOH, I think the Yamamoto books says that this type of detonation isn't problematic for rotaries.

For negative RPM deltas, more advance increases engine braking.

I have run with these tables zeroed, and I didn't have major problems. Still, caveat emptor.

maybe you should explain why in your mind that it even needs to be messed with?

maybe you should explain why in your mind that it even needs to be messed with?

to whom are you referring to?

You, why would I be asking anyone else?

You, why would I be asking anyone else?

Because your question makes no sense -- Fazda never asserted that it does need to be messed with. He merely asked a question.

So, it must be there for a reason, should I leave it or have it pull less timing?

It seems that in turbo applications it might actually be useful to retard the timing somewhat during deceleration, which seems to be the opposite of how things are set up in the OE calibration.

This feature is useful for engine braking under ecology limitations.

In order to avoid rich spices under throttle off it is useful to provide some additional air that is counterproductive for engine braking. Retarded ignition fills the bill.

Secondary, ignition retarded provides inti-lag feature for turbo application if you wish to accelerate sharply after breaking or gear switching. link (http://www.romraider.com/forum/viewtopic.php?f=15&t=6482)

Well it all started looking at 3gear wot logs, right around 5950rpm the car decides its not going any higher, standing on the throttle. Afrs look good, but timming is 5. So I am thinking that having this timming to small that it stalls the cycle, and it cant recover. To early a spark and you loss all power. All my other logs I have seen like to have 9 - 10 on the leading, through that boosted range with out timing pulled. So thats what I am shooting for. I have already adjusted my timing for boost, do I really need another? Maybe this is a rear occurance.

This is what those tables ought to look like:
http://www.rx8club.com/attachment.php?attachmentid=179781&stc=1&d=1324410863

So, if you are seeing timing that is 3-8 degrees retarded on the leading and 8 degrees retarded trailing, I think there is a good chance these tables are the cause.

Whether or not it should be "fixed" is really a judgement call.

Ah thanks, On the previous page I posted my rpm and timing portion of the log. have you had positive result in adjusting this table for boost?

Ok, I will sit back and watch you run him in useless circles then

Please, if you have something to add, please do, if you dont want to share it openly I have an empty pm box :)

You don't adjust anything for boost in the RX8 AP. You adjust for load. The difference is subtle, but you need to understand it.

If the engine is stalling at 6k then the problem is elsewhere. The timing would have to be mega-fubar to be the cause of this.

Ok, ill keep looking.
as a side note wont the power suffer with that kind of timming pull to 5 degrees?

in reference to what? You haven't provided much info. We would need to know the parameters that were occurring then, such as a log, etc.

log.....

Is that log when it's doing it? Would expect higher TP if you were "standing on it" ?

I'm starting to think the problem is obvious, lol

The brain attached to the foot that runs the computer taking the logs? ;)

I was only kidding, but nobody can be of any help without the proper information

Open excel, click file, open. select all files open text file. Text import wizard opens. Click next. Under delimiters checkbox comma, click next, then finish.

Rx8club does not let .csv or .exel files to be attached

bump

thinking out type

I am hoping its obvious,
the problem is me
you don't have enough info to help me

dannobre looked at my logs and noticed

Throttle Position = 67 (did a search this is the normal max)
Accel. Pedal Pos. =100

I am beginning to think I got it backwards, perhaps the hesitation is causing the timing pull.....

2nd gear
http://farm8.staticflickr.com/7014/6608921589_48e51328e6_b.jpg

3rd gear
http://farm8.staticflickr.com/7022/6614054969_bb3d64c7af_b.jpg

much better, thank you

now can you provide us with a detailed description on what is occurring and when relative to the log?

This is a third gear pull, car accelerates fine, then around 5800 the cars tone changes and it stops accelerating, no jerks, no jolts. Just stops accellerating

Please send me your email address

Done

updated post47

hesitation is gone, but timing pull still occurs
Do I need to address the RPM Delta table?

RPM Delta Table = accelerator position Delta table? wouldn't be the first time cobb made a mistake.

"Acceleration Ignition Map - Ignition timing can also be corrected for a rapid change in the throttle opening rate for a smoother transition into wide open throttle."

Did you ever resolve this?

I'm starting to think that there really is quite a bit more to the timing strategy.

Have you tried disconnecting the knock sensor and resetting the memory?

Still happening.
This is on a new engine installed. I have thought about resetting the ecs again. I think the rpm delta uses the knock tables perticularly the increments and decrements and max. I made some minor adjustments but have not tested it.

Iat.

Iat.

talk to the hand, or rather might as well be ...

I just wasn't sure if I had mentioned it here previously.
My hands are good listeners.

It was stated numerous times by various people just like your maf number comment in the Greddy compressor map thread

hesitation is gone, but timing pull still occurs
Do I need to address the RPM Delta table?

RPM Delta Table = accelerator position Delta table? wouldn't be the first time cobb made a mistake.

"Acceleration Ignition Map - Ignition timing can also be corrected for a rapid change in the throttle opening rate for a smoother transition into wide open throttle."

This actually makes some sense

RPM Delta Table = accelerator position Delta table? wouldn't be the first time cobb made a mistake.

No - the RPM delta table is the RPM delta table.

Obviously, RPM delta is affected by throttle opening angle and rate, but it is not the same thing.

I have been seeing logs that look just like mine, similar setup, and it has no timing pull, similar intake temps, g/s, and load. Maybe this only effects newish/healthy motors,

There is a knock learning strategy in the ecu and it looks just like what is implemented in every other Denso DBW ECU, right down to the values of certain parameters.
I'm not good enough with disassembly to understand exactly what, if anything, it is doing. However it doesn't seem like Cobb understood it well when they stopped working on the RX8, or for that matter even today on the Mazdaspeed cars.
So, there could be a knock learning table in ram affecting timing advance, and it wouldn't show up under the knock retard pid.

The routines are present.
Unfortunately, the Renesis knock sensor cannot actually hear detonation, so it doesn't apply any retard based on actual timing events.
I have analog datalogs of the sensor and the only thing it can hear is a bad motor mount.

Analog datalogs?
It is a linear knock sensor, if you didn't see a signal then the sensor was broken or you didn't measure it correctly. More likely you thought it was a resonant knock sensor.

It is a microphone, and the response is linear throughout the audible range. If you can hear it, the knock sensor certainly can.

The Ecu filters knock from noise.

You clearly have no applicable practical experience with regard to the RX8.

This is how the knock retard value gets converted from a float to an unsigned integer for transmission over CAN.

http://www.rx8club.com/attachment.php?attachmentid=180848&stc=1&d=1327786877
This shows why no one ever logs knock retard.

I'm sure Team can explain the rest.

So are u saying that the knock senser is pulling timming, but datalogs does not register it??

I'm saying:
- We can't log rough or fine knock learning corrections.
- Turns out, we can't actually log knock retard either.
- The assertion that the knock sensor cannot hear detonation is ludicrous.

Linear/flat response knock sensors hear everything. The ECU then has to use filters and FFT analysis to discern knock from other noise. You can't just look at a scope trace and determine what the knock signal is, though you could with the old resonant knock sensors.

It is difficult for me to say exactly what the KR system is doing in practice. Racing Beat says (http://www.racingbeat.com/mazda/performance/rotary-tech-tips/rx8-ignition.html) the system is too sensitive. They may have been monitoring knock correction parameters in ram directly through the AUD port or mode 23.

You are seeing timing pulled, and it seems to me that knock correction is a potential cause that has been discounted by some for dubious reasons.

Let me rephrase the question

Is it Possible that the system is in fact picking up knock, then reducing timing, but the knock value we see in Datalogs will remain 0????

Let me rephrase the question

Is it Possible that the system is in fact picking up knock, then reducing timing, but the knock value we see in Datalogs will remain 0????

Yes, there are three ways that knock can retard spark. We can't log any of them.

Very interesting discussion.
I know zero ... but I'm lurking thanks guys

yes, there are three ways that knock can retard spark. We can't log any of them.

thank you!!!

Yes, there are three ways that knock can retard spark. We can't log any of them.

Absolutely incorrect.

Start your log and take a medium-sized Crescent wrench and lightly tap the left-side motor mount.
Observe your logs.

Oltman is looking at code, perhaps we can log major events but not minor events, but minor events can still pull timing?

If thats wrong, why dont u tell us exactly whats happening?

The timing retard value that we log doesn't care what the "source" was. If there is a value shown, then that is what is pulled from the calculated timing value.

Why can't you guys just go outside and try the experiment? Is it really that hard or do you just prefer to throw ideas around without having to be responsible for them?

I did do the experiment, and yes there is a knock detection when hit hard enough.

but when my car pulls timing at 6000rpms there is no knock detection!!!

but when my car pulls timing at 6000rpms there is no knock detection!!!

How do you know it is pulling timing?

some things just aren't meant to be ....

http://www.chapso.de/galpics/2010/12/09/412453/21977/6991f5-1291868783.jpg

How do you know it is pulling timing?

The datalogs, that are posted in this thread....

The datalogs, that are posted in this thread....

you continue to miss the point, entirely ...

you continue to miss the point, entirely ...

Enlighten me,

Btw I emailed you my timing map and u never replied....

edit: apology my bad, sent you email

.

The datalogs, that are posted in this thread....

You show the timing being pulled, but you don't show anything that indicates it is knock. Because it isn't.
I already explained to you what is happening back on the 18th.

You show the timing being pulled, but you don't show anything that indicates it is knock. Because it isn't.
I already explained to you what is happening back on the 18th.

Whats wrong with the IAT?

No - the RPM delta table is the RPM delta table.

Obviously, RPM delta is affected by throttle opening angle and rate, but it is not the same thing.

Those tables are looked up based on the difference between measured RPM and desired RPM. Desired RPM looks to be set by the the idle tables, or when off idle it is set to RPM itself. I don't know it this ever actually amount to anything like a delta. No reason to speculate though, you can log desired RPM with any scan software that has the Mazda enhanced parameters. If anyone uses Torque for Android, it is mode 22 pid 0x96e. Scaling is x/4. I broke my Elm327 dongle or I'd do it myself.

In any case, this correction seems to be mainly for controlling hunting idle.

Desired rpm isn't used for much else, but it also looks up base idle timing. I'm not really sure why you can cause feedback knock retard at idle, but it is tangential to the candidate issue. It does highlight one important point: 0.5 load is the maximum for feedback knock retard. This is mislabeled in my version of AccessTuner.

Meanwhile, one of the knock learning strategies only starts at 0.5 load. There are also IAT limits for this stuff, so you could probably disable the whole system by miscalibrating it...

I think we need a utility like Learning View (http://www.romraider.com/forum/topic2772.html) to look at the learned parameters. If you're satisfied with what has been divined from crescent wrenches and defended with hand-waving, I have not a fuck to give.

Did you see this as a change in timing or an actual knock retard value?
If it is only the former, than the knock sensor had nothing to do with it.

It is likely that you have bad IAT values being reported sporadically.


You show the timing being pulled, but you don't show anything that indicates it is knock. Because it isn't.
I already explained to you what is happening back on the 18th.

What FazdaRX_8 have to show in order to indicate that it is knock and not just timing being pulled ?

If you're satisfied with what has been divined from crescent wrenches and defended with hand-waving, I have not a fuck to give.
At the end of the day, that is all that matters to anyone that is tuning these things.
If you are only interested in parametric masturbation, I have an equal quantity of fucks to offer.
What FazdaRX_8 have to show in order to indicate that it is knock and not just timing being pulled ?

The actual knock decrement value, which he has already said shows zero.

It does highlight one important point: 0.5 load is the maximum for feedback knock retard. This is mislabeled in my version of AccessTuner.

Meanwhile, one of the knock learning strategies only starts at 0.5 load. There are also IAT limits for this stuff, so you could probably disable the whole system by miscalibrating it...



so anything above .5 load would not be logged in knock retard?

? Bump

I have been experiencing this very issue and based on all my available data, the knock sensor is the culprit.

Looking at the code oltmann posted, there does appear to be an error present with regards to the logging capability. If I'm reading it correctly, any timing retard value less than 10 will always show as zero. It just so happens the max knock retard value is -10.

I have been running a very conservative timing map so my issue would compound itself. The sensor would think it hears knock (due to unknown reasons), pull timing which would then actually create a misfire causing further timing to be pulled. IAT's were all normal during this time and the RPM delta tables were zero'd which did not solve the issue.

After reading a post previously made by Kane regarding the knock tables, I zero'd all of them and the problem has gone away. No misfires and my timing is being set to what I have in my base table.

For all I know I have a failing left motor mount that is causing the sensor to freak out.

I think the jury is still out on this issue but removing the knock tables from the equation completely fixed the issue for me.

Good work Flash .
Is this under boost or NA ?

I always limit the knock retard value by about half anyway and don't see any misfire either .

I am keeping mine stock,

I mean if you flat line them all and you get bad gas, what keeps your motor from blowing?

Proper tuning ;)

Yeah, where do you get one of those?

Good work Flash .
Is this under boost or NA ?

I always limit the knock retard value by about half anyway and don't see any misfire either .

This is under boost.

Something has clearly changed in my setup as I never had this problem previous to doing the Turbo rebuild. For all I know I damaged the driver side motor mount with all the moving of the engine and the knock sensor is picking it up.

While removing the knock sensor's capabilities might not be ideal, no one should depend on it to save your engine. With the sensitivity to knock that the rotary has it is very possible you would destroy something before the PCM had time to react in the first place.

I have been looking into the mazdaspeed 3 ap, and knock stuff. Cobb gave up early on us. The knock sensor I think works fine, we just cant see what is acually reported. Other then logging timing and compare to comanded.

I do think that the kr system can save an engine from predetination, due to bad gas, that is why mazda has the system, incase someone put in 87octane.

The only way to get a "proper tune" for it is to tune with bad gas...

The only way to get a "proper tune" for it is to tune with bad gas...

Not at all. You can build in safety margins within the tune to account for poor quality fuel. That said, the best thing you can do is ensure you use quality fuel with octane ratings that can be accounted for and stick with it.

I've made a habit of carrying a couple gallons of Xylene with me when I make road trips to areas of AZ that I know have crap gas. In the end, that stuff is cheap while engines are expensive.

You could zero the table out for a test just to see what the result is :dunno: just make duplicate map with the tabled cleared and do a simple back to back comparison under the same conditions. It doesn't get any easier than this.