Findings and conclutions about misfires and ignition pulls

135boost

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Hi

I started this cause there seems to be numerous different approach about this stupid and very annoying issue of n54 misfires

I think half of those is just related to worn out parts like stock coil, plugs, faulty injector or just clogged intake runner, piston ring land, or something else very obvious.
But then there seems to be a bunch of misfire issues not covered by those common easy fix and owners has throwed and swapped every part in whole engine department and still struggle with this issue.

First this engine is still just a petrol burner, air, fuel, squeez, bang, exhaust dump..
I have struggled with these for few years now and still miss the root cause for them. Trebila has been awesome help and p33p33 even more awesome help to tune this but still there is to much on the dark side of this issue, and for sure, i'm not the only one with this. This seems to be stupidly sensitive to all what can cause misfires.

At the end of day, solutions should not be in a level of "edge where maybe it ignite every pulse", more like enough room for to be sure we aren't even close to misfires, damn, gtr's with these miniatyre plugs iginite even with 55psi and 2000 horsepower and propably 40% more cylinder pressure at the moment of ignition without issues.

What i have read from these forums, numerous injector swaps, numerous playing with different coil packs, spark gap, finetuning of software, different plugs, wichcraft, gremlings, different brand of fuels etc and still misfires even with big players like Tony @ vtt, Terry @ burgertuning and numerous others too.

Damn it, even 1970 made carburator engine turbocharged ignite mixture without issues so why is this so damn difficult.

First known real issue, miniatyre size spark plugs what for sure is more prone to run to issues cause of very thin layer of insulator and frame been close to electrode, that is somethinw what just is, caused on limited space in combustion chamber in di engines.

Then few things about di and plug relation what can trig issues, injector is very close to spark plug and with very high horsepower n54, on di, when injection window start (not sure about excact timing cause of missing map in xdf but some guess is that window is some 250 degree ) piston is close to tdc and maybe there is on big injection quantitys in that situation to some degree of risk to wet the plug.

First question, have there been any notices of difference in full di to the max with bigger di hfpf systems versus di plus pi cause on that occation, di plus pi should be less prone to this if that is the case

Second question, b58 style spark plug with much more protected center electrode could also provide some protection against that wet foul possibilities, some notices if that does any positive effect against misfires. Someone maybe even tryed pi only?

Seems that pr coils, b58 coils etc has for sure enough energy to ignite this kind of combustion so i think we all can be sure it's nothing to do with pure spark energy. Energy need is also reduced with spark gap reducing even if combustion pressure increase energy need and spark resistance at level of 1 to 1

What about mosfets or cabling to coils, i don't think cabling are too small to proper support coil charge even if they ain't ment to support more than stock coils but what about mosfets ability to disspatch heat with much longer dwell times in optimated dwell maps? I really think we have enough knowledge on those proper optimum coil dwell tables to rule out thatwrong chargetimes from issue causings list.

There has been one test what i have found from web where those was measured and conclution was that b58 coil is superior to allmost everything what can be throwed in in dumb coil markets. Has there been any taughts on temperature issue or is there real differences when used smart r8 coils on misfire front?

What about heat sink glued with thermal glue on top of all mosfets? Not so very difficult task to do.

On mechanical side there has been reported that some teflon tape wrap to injector has cured a small amount of misfire issues, sounds like bush fix, it may work but not caused of better sealing to combustion, it should worse out that sealing situation caused by many time bigger area to be sealed than that orginal 8mm but there is one thing what on my opinion has been totally missed and what that teflon tape could on short term cure.

What if the issue on that is not gas leakage, but jiggering of whole injector as a result of combustion chamber high pressure pulses?

Seems to be that issue is escalating with boost pressures over 25 psi and that teflon wrap fix has been when there has been complains about injector bore been out of shape or loose.

I came to stupid taught, what if that big cylinder pressure is starting to resonate the whole injector against the injector holding clip, that could easily explain wear out injector hole, that for sure could cause very erratic injector behavings caused on movements inside of injector and it's needle. Area of injector is in size of 0.5cm2 (8mm cross section ) at injector injecton nose where that teflon seal sits so if there is some 100bar cylinder pressure at highest point, the spring has to be hold some 50kg force and i'm sure it does not withstand that without some warping or small resonation. What if the injector locking spring is orginally designed to work as some kind of hydrolock protector to give up after example double orginal cylinder pressure and designed to protect pistons and stock rods in a case of injector fairlure and pump combustion chamber full of gasoline? And then when we reach that level with double absolute charge pressure, what is in a level of prox 40psi compared to stock some 20psi abs, 14,7psi plus some 7 or 8 psi boost? Just playing with idea...like valve float, difficult to show out as small amount until it's sewere issue an can be heard.

On these n54, that resonating frequency is in a rateof 2500 to 4000hz, half of engine rpm so monitoring should on my opinion be done with high speed videocamera in a dyno under full pulls to se if there is a issue. That spring type injector holder is not to be seen in any diesels, tfsi, n55, b58 or other engine models so what if this is the real issue in these n54's and was at the beginning a idea of bmw engineers to do it as that mentioned protector cause it was their first di engine?
I think movement level to mesh up injector is in a level of 1mm or something so movement does not have to be even visible to eye without slow motion diagnostic video.

Easy fix for sure is stack 2 springs to clamp that injectors, doubling it's clamping force. Has anyone even tryed that?
I have a spare of those and for sure will throw them in to do road test to it but i don't have easy access to chassis dyno or high speed camera equipments to do real investigatios other than road tests.

On afr side to solve this issue, it seems to be regardless of afr, for sure very rich mixture is causing misfires but even of correct best power level afr or little on lean side of it, it seems to be a issue still having mystery misfires.

Next question, if that is dme related, then all with syvecs s6 or s7 should be without any misfire issue at all, is that the situation? If it is, then dig again us in to dme mosfets.

In some occations, there seems to be claims that weak battery is causing these kind of issues but
That should stress more generator than trig misfires if dme feed voltage stays on decent level.

For sure i know this is a network of different bus in these so maybe there is some relations caused of some mystery module like lfpf but i think it's long shot.


My setup starts to run to misfires in a region of prox 23-25 psi, tested 3 different injector packs, 3 different coil packs, both pr and n58 coil packs, slight different afr's, diferent plug gaps, different dwell table values, even p33p33 knowledge, and misfire is popping up somewhere in 6000-7100rpm at every pull with at least one gear recovered after second or two to normal again and to the point of misfire everything seems to be totally normal except ignition pulls
Propably related to some torque limit table, 6at (testing at the moment on 29psi and target at the end is 33psi with 1:1 boost exhaust pressure) what i think is a totally other issue.

That ignition pulls has been reported that is more prone on xi models, and if so, it can be related to noise from dront diff ve rwd cars, more than diferent in calibrations or something else, faulty prop shaft or half shafts can bring noise to oil pan what can trig it but on mine, i tested few pulls with knock deactivated at over 3500rpm and still puls so it's not knock in my situation.

Known trigger increaser is forged internals, check, high lift cams, check, closed deck, check, xi, check, so i have them all.


Taughts?, suggestions to keep my mouth shot? Ideas ? And yes, again, i know my english is not perfect so gramma lections suggestions don't belong here eather or could it be better to write on my natives Finnish or Swedish 😛
 
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Solution
“We choose to tune bmw n54 in this insanity and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one ... so.. is it even technically possible to increase that 1389 value or is only path port injection

135boost

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digging little deeper in to funktion rames of these MSD80 and MSD81, it`s more than just hint that Carabuser is on the track with that Notlaufmanager, there is huge amount of limit values behind that Notlaufmanager what to trig

this is from document 4cc4jm0e page 1515 forward

-max torque (propably not this issue, according xdf, no torque limitations)
-max rpm (not this issue, max rpm is at 8000rpm and issue starts at 5600)
-dwell( not this issue dwell is constant and under control)
-statusvalues (not yet figured out what this is)
-priority variables (not yet figured out what this is)
-sequential spark (not this issue, according xfd, run on single spark)
-agr intervention (it should not be this)
-spreading procedure (maybe something to do with this )
-driver torque detection (should be under control, at least according xdf)

-BAW not allowed (this is strange) -->operation mode request , can be some real issue, demand for different operating emergency modes, k_bawu_nl 1,2 or 3

-BAVB (this is switch between hom,h+s or s mode, not issue on my opinion)

-lambdaselect not accepted, this is only place where i find bank selection ********** , one variable is rev limiter.


then jumped to 4cc3kmos pdf

on around page 4280, there is some way explained o2 sensor diagnostic and that can cause this kind of strange issues too.

If LV_DIAG_CDN_PLAUS_LS_DOWN = 1
and LV_INH_DIAG_FL_LS_DOWN = 0
and C_MAF_INT_MAX_DIAG_FL_LS_DOWN > MAF_INT_FL
> C_MAF_INT_MIN_DIAG_FL_LS_DOWN
then Diagnosis available
LV_CDN_DIAG_FL_LS_DOWN = 1
else Diagnosis NOT available
LV_CDN_DIAG_FL_LS_DOWN = 0
endif
Formula section:
If LV_CDN_DIAG_FL_LS_DOWN = 1
then If VLS_DOWN < C_VLS_MAX_DIAG_FL_LS_DOWN
then FL signal plausibility fault present
ERR_SYM_FL_LS_DOWN = sym_3 /"FL PLAUSIBILITY ERROR"
/Error Manager shall debounce this symptom
else
ERR_SYM_FL_LS_DOWN = "NO_SYM"
/Error Manager shall decrement the debounce counter
endif
endif

what does that FL_PLAUSIBILITY_ERROR do in logic ??

then what is to be found in page 4284

there is 2 variables, full load and rich conditions

seems that this logic goes like this, there is a limit in full load maf value (MAF_INT_FL) and it`s to be used in case of longer full loads or longer rich conditions (what is case in my wot runs) this will reset if full load condition no longer excist (LV_FL from 1 to 0) or VLS_UP no longer indicate
rich condition ( mode 15, extreme lean)

this seems on my understanding separate calc maf vs raw calc maf values and drop closed loop lambda from usage and what that do is
my kind of strange behavior, there is too those time frames and resets.
 
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carabuser

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Notl_wahl value of 15 means the reason for the fuel cutoff is pre-ignition knock. It applies an ignition cutoff for a set number of cycles.

Basically the knock sensors are picking up lots of noise in the pre ignition window. You can disable this using this parameter:
1654959978361.png


If you set that to 0 then pre ignition knock control will be disabled.
 

135boost

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I tested allready to disable all knock related modules, and at the moment knock is disabled at 5400rpm but it does not seems to solve this.

Like i wrote before, it does not drive fuel cutoff, it reduse whole bank injection time by 35% and that for sure is some issue. Logic with fuel cutoff yes but logic to drive it to extreme lean 17 afr when knock is detected, no.. and yes, there can be some knock noise and at start, it start first to reduce ignition advance.

What i wrote before, on previous post, on msd80 document, there was explained on possible cause what could explain all this kind of one or 2 bank issues.

Is maf_int_fl limit value findable, what it value and how much is there room to increase it?
Because what i got from that document, it follow maf until maf max treshold is hitted, then check if full load exist, and if both exist, check for rich condition with some treshold, trig emergency, pick reduced sensor input precalc maf values until afr goes lean , trig fuel mode 15, and that switch it back to mode 2.. then same again after some time window
 
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135boost

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I'm just telling you exactly what the problem is. If you know better then keep at it.

I am very thankful and prishiate all help i can get with this, and for sure you are much more capable of these kind of issue solving and i'm sorry if i sound stupid or rude on this, my native language is not english, not even second language so it's not so floating to explain issues.

I disabled knock control some time ago at prox 5400 because my engine for sure is noisy, piston skirt clearance is bigger than stock, more aggressive cams etc so suspect of this was first knock or misfire module issue..

😬😬
 

135boost

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This was that notl_wahl what i was digging in funktion ramens, not only to adjust things but also to try to understand what is behind those values.

What i get from logic, all notl_wahl come first trough MDBANL_Main_auswahl module, page 1509 what separate all mechanical emergency issues out from logic, like vanos, or similair issues, then logic continue to MDBANLMain_umschalten module on page 1512.. 4cc4jm0e pdf




Ps, there was settings on pre knock control on my bin, it was 5600, not 5400rpm.
Pic 2, so if this is knock, it was off from5600 and this jerking is over that rpm limit so if mode 15 is knock, it trigs some other thing too.


I'm well aware of difficulties to explain shit like this and for sure there is too much variables to everything to be taken note of.

One thing that can affect this is that i have only one secondary o2 sensor in use on my car because of strange wave effect caused by the other one when it was in use and (afr wobble between 10-18 under light load) and what i have now got from funktion ramen, that can be a full load issue, this issue was modifyed some year ago with P33P33 and we did decision to use only one downstream O2 sensor.

those explanations below can explain all wierd shit what is happend inside this N54 and maybe dozens of other too. there is limits inside this bin and they can affect quite much things what is not to be in mind when adjusting so maybe example that o2 sensor miss is causing this shit in my engine.


On this pic 3, there is bunch of values what can be reason to this whole fight
First this is allways FL issue what is full load (don't have tools to determine full load condition in MHD)
This happend at prox 400 maf what can be definition of full load ?

my wish list is this to tunerpro as maps
One value where i could want to get my hands on is C_MAF_INT_MIN_DIAG_FL_LS_DOWN to get it if possible away with max value 1820.42 added to it what mean 50.55g, then maybe MAX value too
Next is C_MAF_KGH_MIN_LS_DOWN_DIAG to push it too away if possible.
Third is C_VLS_MAX_DIAG_FL_LS_DOWN
fourth is MAF_INT_FL max value
fith is MAF_INT_FL_ACT timeframe
maybe determination of rich condition to lower value..

and some of those to MHD as logging parameters to log out trig values where shit happens.

this text is the one irritating me at the most
>
The calculation of MAF_INT_FLexpires in 20ms raster as long as either the operation status FL is
fulfilled or VLS_UP indicates rich conditions, depending on the setting of LC_MAF_INT_FL_CDN_
AFR. The integral is calculated even when the application conditions for the plausibility check function
are not fulfilled. MAF_INT_FL is limited to the maximum value if necessary in case of a longer FL (or
rich) phase.
The value of MAF_INT_FL should reset to 0 if the transition LV_FL = 1 -> 0 takes place resp. if
VLS_UP no longer indicates rich.

what i get from this, is that if it overshoot maf max value on full load, and rich condition exist, it will throw this to emergency mode with some time windows and reset is with
-no full load condition, nope
-no maf max value, nope
-no rich condition, yes, because overshoot --> emergency mode-->time frame--> reduce whole bank injection quantity by 30% -->lean -->reset to normal -->follow if it still overshoot-->timeframe-->emergency mode-->reduce whole bank injection quantity by 30% .....




EDITED...

If (LC_MAF_INT_FL_CDN_AFR = 0 and LV_FL = 1) or
(LC_MAF_INT_FL_CDN_AFR = 1 and
VLS_UP = C_VLS_UP_MIN_MAF_INT_AFR and
VLS_UP = C_VLS_UP_MAX_MAF_INT_AFR)
then
MAF_INT_FLn [g] = MAF_INT_FLn􀀀1 [g] + MAF_CYL * T_SAMPLE [ms] * 1/3600 [(g*h) /
(kg*ms)]
else
MAF_INT_FL = 0
endif

i suspect this is the calculation where everything goes left when we have tuned engines and we hit max preprogrammed maf value

conditions where this shit start is
-FL full load
-MAF max value reached
-rich condition

it throw us to this calculation
MAF_INT_FLn [g] = MAF_INT_FLn􀀀1 [g] + MAF_CYL * T_SAMPLE [ms] * 1/3600 [(g*h) /(kg*ms)]
from this
MAF_INT_FLn [g]

and what i get (not smartest guy here) is that when max allowable maf ( prox 400) is reached and full load is achieved with rich condition
dme determ that there is something going wrong with sensors giving maf inputs and jump to emergency "maf values" what is determined stock engine in sight.

i have monitored with MHD my MAF values and if i ignore that 0.8 sec and continue with WOT i reach MAF values up to 540 or so.

we have there few variables what change much that preprogrammed values in this kind of situation.
-stock engine with stock size turbines mean exhaust pressure vs boost pressure reach 3:1 ratio
-less restriction with catless DP
-maybe bigger cams
-maybe bigger valves
-maybe ported heads

all of those turn this preprogrammed calc to left from real values and if we hit that limit, it will throw us to situation that we got reduced
fueling and lean conditopn and misfires and all kind of issues.


what do you think ???
 

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nyt

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Notl_wahl value of 15 means the reason for the fuel cutoff is pre-ignition knock. It applies an ignition cutoff for a set number of cycles.

Basically the knock sensors are picking up lots of noise in the pre ignition window. You can disable this using this parameter:
View attachment 69671

If you set that to 0 then pre ignition knock control will be disabled.

This msd81? What are the rest of the values for conversion?
 

135boost

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HA... YIPPIKAIEEEEEEE.. Carabuser had it right, issue is knock related, there is more hidden behind knock than just
Max rpm to inhibit knock related modules. I think it will follow that logic until some timeframe has gone and then it start to jerk.

I did not have any tools in my xdf to access real issue until carabuser helped to pinpoint where it goes left.. and cause i didn't have any maps to test, just sit and bang my head to wall.. but now it seems to work, rip like shit, rev to 8000 without any hesitation, i think max hp rpm lays somewhere past 7600...

And one log, 100 to 200 was stupidly fast, should be 100kph at 4400rpm in third and 200kph at 6800rpm on fourth



Seems that i need more fuel from pi at over 7300 rpm..
 

nyt

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You have allmost same setup than mine, i just have bigger turbo (2x g25-660)

yeah, I had false knock with this setup before I changed to a closed deck setup, now it triggers super knock. I put this together to try to find a balance. Some nylon spacers got me most of the way there. I'll likely install this within the next week. I wish the rest of the knock tables were defined, I don't have the data or the time to go define them :(
 

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135boost

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like Carabuser told me that it`s knock and seems that that 0 notl_wert 15 is knock and fuel mode 15 is differ issue from that.

one what is building noise to me too is for sure semiclosed deck with all other mods and issue maybe is jump from knock to superknock
where everything start to go left. on knock, it just adjust timing retard but when moderate normal knock is recorded for some timeframe, it trig superknock mode and there is changes to some "safe map" fueling or something and for sure that safe map does not calculate our very much reduced exhaust pressure, fully built heads, bigger cams etc what for sure increase high rpm VE quite much = lean condition

my 10cents
 

wheela

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like Carabuser told me that it`s knock and seems that that 0 notl_wert 15 is knock and fuel mode 15 is differ issue from that.

one what is building noise to me too is for sure semiclosed deck with all other mods and issue maybe is jump from knock to superknock
where everything start to go left. on knock, it just adjust timing retard but when moderate normal knock is recorded for some timeframe, it trig superknock mode and there is changes to some "safe map" fueling or something and for sure that safe map does not calculate our very much reduced exhaust pressure, fully built heads, bigger cams etc what for sure increase high rpm VE quite much = lean condition

my 10cents
This all seems very logical, but I don't understand the intervention the DME is taking in response to the continual knock. Everything I understand says that richer mixture will be more knock resistant. So regardless of changes we've made to VE that the DME doesn't know about, why is the DME responding to continual knock by reducing fueling? I could see reducing load with a throttle plate intervention, but doesn't reducing fueling in this circumstance seems like starting self destruct mode🤷‍♂️

On that note, with disabling all your knock control, aren't you concerned about blowing up your motor? One thing I don't understand well is how somebody determines it's false knock vs. real knock. I guess if your motor doesn't blow then it's probably false knock, but that seems like a risky approach...
 

carabuser

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The DME cuts fuel and ignition to the cylinder to protect it. The bank reads leaner but the other 2 cylinders will probably be at a normal AFR.

It is pretty risky to disable knock. But on built motors like this the knock control is probably meaningless anyway. It's designed for a standard engine so I doubt it was picking up any meaningful knock while switched on. He was getting almost constant -7 corrections on all cylinders before so it's clear that it wasn't working as intended.
 
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wheela

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The DME cuts fuel and ignition to the cylinder to protect it. The bank reads leaner but the other 2 cylinders will probably be at a normal AFR.

It is pretty risky to disable knock. But on built motors like this the knock control is probably meaningless anyway. It's designed for a standard engine so I doubt it was picking up any meaningful knock while switched on. He was getting almost constant -7 corrections on all cylinders before so it's clear that it wasn't working as intended.
Thanks for clarifying, that makes sense. When he said it was affecting the whole bank and that bank lamda went lean I mistakenly assumed it was running all 3 cylinders lean vs. just shutting 1 down.
 

135boost

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I`m well aware of risks blowing engine :)
there should be to find some golden path between total knock eliminating and these wierd issues.

in my situation it didn NOT cut fuel off one particular cylinder, it cut 30% of all cylinders in same bank what was to be seen in injector timing
(from 220mg/stroke to 160mg/stroke for that 0.8 sec)

i think the logic behind this is more calculated to stock engine because you have absolutly right on that self destuctive behavior of driving lean if knock is detected.

i think it`s more like knock or false knock detected ( my corrections 7) no issue with fueling and AFR keeps steady like it`s on every log...
but then sone timelaps or calculator goes over limit value --> superknock or some other mode and there whole ballgame changes because
it`s some kind of emergency mode.

i think that emergency mode goes and read reduced amount of sensor values, it rely more to pre calculated values and read WBLS but not work on closed loop, more like open loop where there is no corrections for fuel and maf is more calculated as stock engine value... booom for sure lean condition appear if built engine built head more cam less exhaust back pressure ....

Here is a pic from fuel mass on individual cylinders
Names on cyl are wrong, it should be 1 phase on all 6 cylinders so this is bank dependant
 

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nyt

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Thanks for clarifying, that makes sense. When he said it was affecting the whole bank and that bank lamda went lean I mistakenly assumed it was running all 3 cylinders lean vs. just shutting 1 down.
It cuts the entire bank in these conditions
 
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135boost

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It cuts the entire bank in these conditions
Nyt has right, normal knock seems to be cylinder dependable but this , what ever it calls, 0 NOTL_WERT value 15 is "superknock" or something like it and if AFFECT whole bank, not single cylinder.

i went trough quite many logs where i had access to after Carabuser did injector phase logging possible , 18 values, 6 cyl and 3 different phases.
those names are wrong, like i told before, there is cylinder 1, phase 1,2,3 and cylinder 4 phase 1,2,3 and correct is cylinder 1,2,3,4,5,6 and phase 1 from all of them.

i`m not sure how much all other tunings make to those swaps and mass wehrt on different phases but one thing is sure.

here is to be seen all 3 different injection phases and vacl combined it inject right value

this run with 1 phase injection mode until some 30-35mg/stroke is archieved, for sure there is more parameters like throttle, map, rpm, what ever.
then this jump to 3 phase injection mode and what i get out of those is that there is H / HS and S in use.

so, this 35-120mg is starting injection first with richer mixture what follow pistonhead preventing knock because it`s piston edges where knock starts. then int inject leaner second phase and again to end a richer mixture what is for sure sum of some ansys or similair fluid flow analysis very complex calcs.

my opinion is that those injection pulses it what it is because no one has any possibilities to inspect 4-8/1000 sec timeframe simulations inside cylinder under compression or ignition conditions.

that continue to prox 120mg/stroke injection mass whereafter one is fall of from injection phase, i assume it`s second phase
what is that stratified phase.

this DME continue to prox 180mg/stroke with that double injection mode, that for sure is way over stock engine fuel demand so i assume
all full load stock engines run to limiter with that double injection mode, correct if i`m wrong.

it can be that stock engine with stock injection mass is left to level 120-130mg/stroke and it run 3 phase until max boost max maf where it just
tip over from 3 to 2 injection phases and pull full power withhout that leaner second injection stage.


then after that 180mg/stroke this jump back to single injection mode, that`s why previous log looks so stupid on fuel injection mass where i logged only first injection mode in every cylinder. this is so much fuel i don`t think stock engine ever see so that`s why i think BMW had done that
2 stage full throttle position ( maybe 130mg/stroke)

that picture was with quite high injection masses ( pi rest of it), total injection mass is around 300mg/stroke and there was clearly visible that when issues come up, it`s whole bank.

i have some 15 logs now with every time same issue, occationally one or borh banks reduction of fuel mass in every injector of that bank by some 30% (210mg/stroke to 160mg/stroke) but it`s not single cylinder, allways whole bank

i think there is logic running from normal map with knock, then it continue normal map with ignition reduction caused by knock and then when
amout timelaps or rpm has gone and cnock or false knock kontinue, it jump to "superknock" table where there is whole different walues and quite much is determined by raw calculations without all of sensor inputs.

now knock maf table was altered, that is on my guess minimum maf where there can be determination od "false reading" of sensors or calibration, eg fuel mass, maf or some other things what is double or triple what was intended and thats why BMW engineers put hidden limit values in the software.. 300hp engine pushed to 900hp is for sure way over intended safety limits and thats why it overshoot values and jump to " emergency" maps or so..


speak is free
 
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carabuser

Lieutenant
Oct 2, 2019
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I don't think the problem is you going over the limits of the the software. Just purely a case of too much noise on the knock sensors.

The routine that monitors knock events has a buffer. It allows a certain amount of knock events in a time window before it triggers the emergency fuel mode. This would be the same on any engine regardless of power levels that is having that amount of knock.

The issue is that in your car the engine is built in a way which generates excess noise which the DME picks up as knock.

You could possibly get the same effect by reducing the sensitivity of the knock sensors in the public knock tables. This would achieve the same effect as people that apply pots to their knock sensors. Although I think this approach is meaningless and equivalent to just disabling knock control.
 
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nyt

Sergeant
Sep 15, 2019
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I don't think the problem is you going over the limits of the the software. Just purely a case of too much noise on the knock sensors.

The routine that monitors knock events has a buffer. It allows a certain amount of knock events in a time window before it triggers the emergency fuel mode. This would be the same on any engine regardless of power levels that is having that amount of knock.

The issue is that in your car the engine is built in a way which generates excess noise which the DME picks up as knock.

You could possibly get the same effect by reducing the sensitivity of the knock sensors in the public knock tables. This would achieve the same effect as people that apply pots to their knock sensors. Although I think this approach is meaningless and equivalent to just disabling knock control.

The public knock tables only go so far. Even if you set them to the far limits, there will still be timing pulls, and even in cases without many timing pulls, super knock will still trigger.

There are a lot of tables that are not in the public XDF, though. Is there damos or other map data available for msd81/ije0s?