Findings and conclutions about misfires and ignition pulls

[135boost]

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

 

[iminhell1]

You must be looking at a different version than I've posted.
MSD80 in those pages is talking about cylinder balance.
MSD81 is talking about the HSO2's.
**Edit**
So the MSD81 does talk about spark later on. I just didn't read far enough.
/Edit


The things you/we need to look for are a pretty clear RPM, somewhere in that early 4,000 RPM range. And something that can relate to single cylinders. Spark is not adjusted cylinder by cylinder. Fuel is though. And the Cylinder Balance is how that's done. You can kinda see how this is done by running the cylinder contribution test in ISTA-D. It shuts down cylinder by cylinder to read each's contribution to total rotational speed (deg/sec).
Thinking about this, maybe it's a clearance issue between the crank sensor and the trigger wheel? I've never pulled mine but just maybe it's gunked up and not reading well enough.
It is odd that it's commonly #6 that's the problem cylinder, and if not #6 it'll be #5. Rarely is it the front bank. Heatsoak and inertia seem to be the logical things here. But there's no logic in the DME that accounts for either. So something mechanical, or harmonic, would be the explanation. I'm just not smart enough to figure out this riddle.

 

[135boost]

That crank sensor was one of my suspision too, that's why i swapped that from my spare engine but it did not solve the issue.
I have monitored fuel flow trough inpa and there is small 1-2% variances between cylinder to cylylinder, 1-3 is maybe average 1% smaller value than 4-6 but i don't find anyting else in those popping up.

Idle is at 130v, cruising at 138v with variances from 137v to 141v injection times from injector to injector is very close to each other etc.

Does ista-d give more detailed information about injection phase and varinces thn inpa?

That continental FR what i digged was a file name 4cc3kmos.... and pages started from prox 916/8404

Those harmonic issues for sure is a pain to find if that is something to do with to trig these misfires

 

[iminhell1]

I believe ISTA-D is more indepth. But it's been some time since I've been able to play with it ... my car is down. The language barrier of inpa was an issue for me.

The MSD80 documentation is easier to understand and gives better explanations IMO. For understanding the concepts it helps me to have both. Even though it's A LOT of reading.


In some misfire detection thread that isn't public, I guess there was talk about the injectors being able to find misfires. Why things have to go on behind closed doors I can't say. I don't agree with it. But maybe it's something else to read up on. Maybe there is something else the injectors and measuring (they are piezo and it's a neat material). Maybe one being loose or a bit hotter is the root.
New injectors never seems to solve this. So I want to say injector condition can be ruled out.

This stuff just hurts my head and causes sleep loss. LOL

 

[135boost]

So up to date situation about these misfires and root causes except of obvious damaged parts.
-injectors it selves is not the root cause or there is no way to overcome some physic limits in them
-it's not caused physically by spark plugs
-it's not caused physically by coils or coil type ( i have not tested r8 coils)
-what ever trig it, we all suffer from that issue if cylinder pressures are high enough
-it's something to do with rpm level over prox 6000
-harmonic vibration, it should be more rpm than cylinder pressure involved so it should be triggered with lower boosts too
-it's not fuel pressure depend because it's triggered in "all of these"


at the moment i`m in a limit of allmost every important part in stock tune and stock DME

-fuel scalars topped to 2.00 at half of the whole map
-air flow hit limit 536, max at the map
-fuel pressure is maxed out (double pumps) and after 6500 start to suffer from fuel starvation, fixed with 1200cc injector
-without rescaling calc torque hits 999
-rev limiter 8000, close to 32x255 max
-i think those double barrels are maxxed out too, wo. That 1200cc additional injector this start to struggle with hpfp pressure too.

with this setuop i try to reach 32 psi @7500-7800rpm And that should hit some 850 on crank at "mustang dyno"

On Finnish rallyguy dynos it shows propably 1100hp

What is left, software limitations, dme physical limits like current supply to mosfets or igbt's, injector physical (don't believe on that), wichcraft, something i`m stupin enough to miss or mess ...

Spark is adjusted some way cylinder by cylinder, at least timing and misfire detection, then that charge voltage treshold must be monitored in my opinion coil by coil to pŕotect IGBT against short circuits and then there must be something to adjust by bank because one feedback protection circuit was for 4 cyl only.

About piezos, they indeed should have capability to act like sensor and send back pressure information to dme but on my knowledge it's not in use in msd81.

Seems to be that worldwide there is some handfuls of people having skills and motivation enough to dig in to this issue and i'm not sure if one of them has solution to it allready (hidden map, wichcraft, better parts or something) what is not public.

there is datazap log to this morning, misfire 5 and 6 with some 205 loads and throttle closure not excist.
sorry for long log and wot is on the end of this log cause of cold start test and finetune of scalars to get stft as close as possible to zero and after this i did some adjustments to scalar tables.

boost only 26 psi because of 5c out temp.

datazap.me | Maantec | Log 1632370857

datazap.me

Ps, that language barrier is my issue too, i have been told in these forums numerous times that my english is so awful that it's close to unreadable, german is not my thing, english is not my native eather...

pps, if it`s possible, send those FR of msd80 and that different fr of msd81 to me cause this what i mess with is for 3kmos

 

[iminhell1]

I have the same MSD81.
But I'd uploaded them to the other site and you can grab form there (replace the u with an i, bimmer not bummer --> https://www.bummerboost.com/g2.php?do=download&file=170

 

[wheela]

okay, one day again with misfires.
to dig out real root cause of this annoying issue, like i started this thread, this is still just fuel,air,squeeze,ign,push,exhaust without any wichcraft.

one hour mission to dig me in to continental FR and pages 910-960 and there is very ... interesting things about this ignition system functions.
if i got it right, it`s not sipmle dwell adjusting, but scaled much to next level complicity monitoring and adjusting of spark.

It start with monitoring coil charge time and voltage rising, that is to be compared to pre programmed table in a limit window.
dme safety circuit calculate amd monitor speed and energy flow to coil, then it decide if coil is charged enough, if that treshold is reached, it reduce or cut the charging process and fire. now if that is compared to stock engine and stock coil values, it for sure cut dwell table values.
then after firing spark, it monitor time and quality of that spark to fit some pre programmed window and it so adjusting to next spark based on those values. for sure there is adaptations to every aspect and like we have on tunerpro xdf file min and max adaptation, there is bunch of other tables too what influence spark duration adn coil dwell / saturation.

there is few more steps to tune dwell time and spark but just to open eyes.

based on that, without any explanations how that all work together and with missing tables, it can be that real coil output in real live is much less than we think because of those background adjustments and for sure that will cause misfires.
possibility is that we buy better coils without any advantage of those if we se coil tests only on testbench what does not take in considering of these background processes.

then monitoring has it`s own specialities, there must be 2 circuits cause monitoring circuit is for only 4 cylinders and we need 2 of those to monitor 6, most likely 3 cyl/ monitoring circuit.

that monitoring work well until it reach level where 3 cyl dwell overrun time of 1 rotation of engine, then it start to throw flag of first noticed
misfire or issue caused of overlapping time.

story is very long but just to throw new perspectives and possible causes of misfires little out of box.

My opinion is that on mhd there should be to monitor dwell and adaptations to it

This is very interesting, I had no idea spark control was so sophisticated. What if part of the spark control system references load? If that was the case, could using the 3.5 and 4 bar tmap sensors be part if the problem, since load is being artificially scaled lower than real-world load (cylinder stuffing factor) to avoid going over 200%? If that was the case, the spark control scheme may not be sending enough energy -when it thinks your at 170% load, it would send spark energy appropriate for a real-world load of 170%. But due to the load scaling for the bigger tmap, when the DME is seeing 170% load, the real-world load is actually much higher.
This would present a much denser fuel-air charge than what the DME would expect for normal 170% load. Any thoughts on this?

 

[135boost]

You can Wheela be right on that, i'm not at the moment able to follow that logic path but it sounds logic that spark energy adjustments take to calculation load too and if that is rescaled, it can be that it's the missing factor to reduce spark energy.

Like i have told before, i tested this with different coil types, different plugs and different injectors and missfire issue sems to be too precise just to be failing component.

In log everything important seems to be okay until it hits and it seems to be with same tune close to 100rpm on same spot and with same load so i have started to truly suspect ignition logic to be some reason for it and if missfire detection is off, it recover that again when rpm level is higher what equal to less ve and therefore less cylinder fill and pressure and on my case with iat adjusting boost as factory intended, lower iat, less boost to keep cylinder pressures equal what ever outer temp is (prox 26 psi at +5c and 30psi at 30c) it hit that same missfire at same rpm on +5c and +30c

With this tune level i have, recovery is done at some 7000-7200 and from there it pulls to 7600-7800 quite normal.
(My real powerband is 4500-8000 with ve max at prox 5000-6000 and not stock 1400-5800 with ve max at 2000-3000 so that stretch to 8000 feels like stretch to 6200 with stock head and hybrids)

That smaller plug gap what i played with couls also be one proof that there inside dme is some kind on coil energy limiter based on calculations of coil charge and monitoring burn process.

Like i told, every 0.1mm reducing was increase boost level by 0.2bar before missfires in my case so it's clear something to do with cylinder pressure at ignition.

Is there anywhere ever done measurements and monitoring in real world of those coil outputs connected to this DME to be sure that coil charge is following dwell table without charge time cuts or any other wierd behavings or is all coil tests done only in test rig (that for sure is important too to get limitations of hardware to be known)

At the end, think if 10 year n54 community continous missfire struggle root cause was from some stupid hidden dme spark energy reducing table and we have spent thousands of manhours and stupidly amount of efforts just to mask the issue.


Ps. Wheela, you play with n55, for sure if n54 has that kind of logic behind spark energy adjusting you can find similair in n55 too with maybe little different parameters but same fuction processes. B58 has these much better coils so the logic can be based on much higher coil energy outputs and compairing to some preprogrammed window can differ much from these entry levels. N54 is 2 meg prom, n55 4 megs and b58 8 megs so there is sure room for gizmos to hide inside it.

Increase of that bin is most to meet different emission measures, that can be divided to 3 parts,white real fair tuning to get everything work, big gray area where all of manufacturers play to follow some ece or similair test patter window and that vw way to cheat mearurements with swap program if hood is open etc.

That big gray area make this software so difficult caused on adaptations after adaptations what is not to be seen in aftermarket ecu's. To get the idea of that complexity, we have things like adjustmets to injector needle temperature depend expansion ratio in these dme's.

 

[135boost]

did some more digging in to msd81 FR (these is my opinion and can be very wrong
dwell is very complicated things in these and for sure it has capability to do cylinder by cylinder corrections.

LDPM_VB_1_IGRE this is known, found from dwell table as voltage = 0-20V
LDPM_N_32_1_IGRE this is known, rpm as 32 resolution and 255 cell = 8160 max rpm
IP_TD is resolution 0,004 as ms

these makes our dwell tables

TD is time Dwell
FAC is ratio
TCO temp coolant
C is time
LV is start
CLC is calculation
SWI is switch
ST is start
INH is indication
SCG signal to ground
SCB signal to battery
CHN is channel

then to be found is
TD_FAC_MAX
TD_FAC_MIN
what is max and min dwell time control as some factor

we find there too
C_TD_FAC_ST_MAX
C_TD_FAC_ST_MAX
what is min and max dwell as factor , 20ms seems to be max value

there is this
NC_TD_LIM
what should be that real 20ms


then to be found is
IP_TD_FAC_MIN
IP_TD_FAC_MIN
this maybe is just value to make that dewll table possible, don`t know

we have too
TD_IGC
what does some cylinder individual adjustmentsand it take in account combustion mode switch too

jump over half and full static cause it`s limp mode things

LV_SCG_IGN
LV_SCP_IGN
individual monitoring of coils short to ground or battery

that propably is not a issue, tresholds to trig those is way too bigs for affect just burning process

V_DUR_IGN
here is burn time diagnosis for spark duration..hmmm at least in my engine that can cause issues if trigger
is too close to stock engine because high pressure affect burn time

ID_V_DUR_IGN_MIN
LDP_N_32_V_DUR_IGC_MIN
LDP_MFF_SP_MV_ID_V_DUR_IGN_MIN
there is hidden some map for minimum burn time diagnose ignition errors, that could be one to alter to get a little bigger margins

NC_IGBT_CUT_OFF_T
this maybe should be as factory value, time to cut off igbt if overload occurs, maybe some 10% could be increased ??
NC_INI_CTRL_DEAC
treshold for switch off, maybe factory value is ok, this is still only as filter against parasitic spikes, there can be those parasitic spikes too
so if nothing else help, alter this
NC_T_MIN_SCP
minimum time to detect shorts, nothing to alter, this phase is done due coil charge power stage

note, this is one of places where weak battery maybe affect this ignition phase

these 3 is monitoring that coil charging phase and there is a fixed treshold value what is higher than coil saturation value but....
on my opinion, this fixed value is STOCK COIL saturation value so when we charge these aftermarkets, is there that cut off coil charge treshold active and give us weak sparks.

then we jump to burn time measurement

we have value
V_DUR_IGN
what monitor and evaluate primary overvoltage duration, aim to detect and measure spark duration

this is most ment to give signal to
IGN_DIAG

not sure how that effect anything

then stacked to all that, we have dwell time adaptations and their inputs
CTR_TD_AD_SWI
LV_TD_AD_ACQ_VLD
LV_TD_AD_SWI
T_SUM_TD_AD
TD_AD
TD_AD_L
TD_AD_H
LV_ERR_CAM
LV_TD_AD_H
T_THD_IGCFB
C_FAC_DEC_TD_AD
C_N_32_MIN_TD_AD
C_T_SUM_TD_AD_MAX
C_TD_THD_IGCBF_MAX
C_TD_AD_INC
C_TD_AD_MAX
C_TD_AD_MIN
C_TD_AD_THD
C_TD_IGN_OL_MIN
LC_TD_AD_CLR
my opinion is that these should be overrunned so they does not alter dwell at all but now them
do much of wichcraft and come out with max and min dwell time adaptation.

these was cylinder independent values

it can be best to do dwell adjustments out of these values and leave min and max values as zero (my opinion)
to get rid of these adaptations just to get everything simpler
there is one thing
PRM_CYL
this can do adjustments cylinder by cylinder but dwell adaptation min and max in xdf is to all 6.

we have then
LV_INH_TD_AD
indicator if adaptative function is inhibited, not so interesting thing
LV_TD_AD_H
indicator if adaptative funtion is done in start, not so interesting thing
T_THD_IGCFB
this should be visible to know if dwell time and therefore coil charge phase is cut for some reason
TD_CLC
this should be visible too to be sure there is no adjustments we don`t want

TD_AD is allways 0ms at start, so it does not remember last session.

then it start to adjust it from start where
TCO temp coolant has it`s influence as factor what is
TD_FAC to TD_FAC_TCO so what if we have that .0930 cold engine value all over the cells ? this can do drastical difference in dwell ?
**********************************
then just to jump in to ECT_FAC, that can be one main key to influence our dwell because dwell should be longer in cold than hot engine.
variables is between 0.930 to 1.000 stock

what if we have that .0930 cold engine value all over the cells ? is this maybe the way to cheat more dwell if DME is really adjysting it in background
**********************************
we have few other interesting values here too that can and will affect dwell,
C_TEMP_MDL_IGC_HYS
C_TEMP_MDL_IGC_MAX
this is from multispark part but this seems to calc and monitor coil temp too

there is few
C_TCO_TD_AD_SWI
swithc over from start phase to normal running condition

NC_CFB_DIAG_SCP_CHN
start phase only

NC_TD_AD_CHN

datazap.me | Maantec | Log 1632587127

datazap.me

There is a log to 5000rpm, no real issues refer to driveability, did some wgdc base mods and ignition tunes after that but if there is something i missed, pleace point out it


This was with ECT_FAC 0.930 so it does not solve this issue
note 1
maybe it was my mistake to not understand logic, i had that adaptation max at 0.00 so maybe it was limited by that because of those corrections is to raw values.
note 2
tested value 1.15 too, got misfire in cyl 2 and 6
note 3
that 0.930 to 1.000 should increase dewll in cold so it must be some divider factor so i go forward and test 0.850
as value hotand have that max adaptation back to 2.00
note 4
reason for recovery is maybe not that cylinder max pressure drop caused on high rpm ve drop, recovery sequence is maybe caused of open loop and there fore dwell calculation parameters is only battery voltage and engine speed related because engine jump to open loop if misfire occurs and it shows stft as 0 in misfired banks.
Note 5 timing pulls seems to be boost and boost target related, did few pulls to 5700 today with load increased and got there without pulls, must reduce little wgdc base from 5700 forward to not overboost .

and at last, log with multiple test pulls and last to 6130.. misfire cyl 5 and 6. this was with 0.930 setting and o adaption max

datazap.me | Maantec | Log 1632589896

datazap.me

datazap.me | Maantec | Log 1632682926

datazap.me

 

[135boost]

Issues continue, seems that misfire strike all times at 6140rpm +-some 30rpm what is for sure about log resolution.
Now with this tune both banks and at same rpm so i don't think it's a hardware issue, more like some dme depending thing.

I have manage to get that misfire now 5-6 times in a row to that excact same rpm and from my point of view, nothing explain reason for it and i start to be quite sure it's dme logic and some hidden "feature" what cause that.

These logs was more like tune rpm range between 1250-4000 rpm and seems that i miss some 30-40nm still between 2250-3500 but tomorrow morning tests with little finetuned vanos.

datazap.me | Maantec | Log 1633894108

datazap.me

 

[carabuser]

If you're starting to dig into the FR then you will want to start logging custom parameters as it's impossible to fully understand what's happening without being able to see the live data. With MHD it's possible to log any address in the RAM so if you see any that would be useful then I can put together a custom logging file that you can use to add more logging params into MHD.

I'm no expert on knock calibration or even the detailed workings of DI but in your situation I would be focusing on getting your fuel pressure in check before going down a rabbit hole. Although not misfire related I'd also question the engine timing being so low until 4k RPM, is that on purpose?

 

[MR-KRAKA]

Not to oversimplify this but have you tried the common workaround for misfires on dual mass flywheels and such? If you haven't done this already, instead of using the global disable misfire detection try toggling that back on and just lowering the max misfire detection rpm (c_n_max_mis_at) to 5k rpm as a test. I've never used that global toggle, it may be overridden elsewhere. I have always used the max rpm method in the past to confirm a true misfire or not with success.

 

[135boost]

Hi Carabuser, nice to get respond to tricky issues.

First, ignition below 4300rpm is for purpose, some 12 cell from 1500rpm at 100load to 4500rpm at 170 load and purpose is as "antilag" to get boost treshold as small as possible. That same is going on with vanos tables too and tuned with some 150 logs just to get most of spool rpm under 4500 where this engine wakes up.

About hfpf pressure, i can reduce it by small amount to come away from max pressure but i don't think that will solve this issue.

In case to log something with mhd, just to rule out something, most important on my point of viewshould be to log true dwell time, soi and eoi or injector total injection time because i'm quite sure there is something odd with one of those

 

[135boost]

Thank you mr_kraka too to throw new point of views to these kind of mystery missfires.

My car is at6 4x4 so no playing with dual mass flywheel.

About missfire detection, if i toggle it to disable, it just hide the issue to not been detected from fault log and it recover autmaticly when conditions is normal so i kept it enabled to see what cylinder is missfiring and rpm seems to do that same over setted rpm

 

[carabuser]

Hi Carabuser, nice to get respond to tricky issues.

First, ignition below 4300rpm is for purpose, some 12 cell from 1500rpm at 100load to 4500rpm at 170 load and purpose is as "antilag" to get boost treshold as small as possible. That same is going on with vanos tables too and tuned with some 150 logs just to get most of spool rpm under 4500 where this engine wakes up.

About hfpf pressure, i can reduce it by small amount to come away from max pressure but i don't think that will solve this issue.

In case to log something with mhd, just to rule out something, most important on my point of viewshould be to log true dwell time, soi and eoi or injector total injection time because i'm quite sure there is something odd with one of those

If you give me the symbol name of the signal you want to log I'll get it sorted.

 

[135boost]

I think it's td_clc

That should be if i get it right end of locic path for dwell calculations and is one value what could tell if there is some mess with coil charge

 

[carabuser]

I think it's td_clc

That should be if i get it right end of locic path for dwell calculations and is one value what could tell if there is some mess with coil charge

Unzip this file then put it into the MHD root folder and you should see an extra parameter in your logging options called TD_CLC.

 

[135boost]

I will test that parameter output in one hour and tell what is shows.
For sure that does not solve the issue but it can open path to find the real cause for
This platform tendency to be prone for misfires.

Like whe i started this whole topic, these misfires in my opinion is most just wear of parts, weak stock coils, injector issues, and plug issues but then there seems to be that black hole starting from some 25psi upwards depending on exhaust back pressure, cylinder peak pressure or something where close to all hit some mystery high rpm struggle and that maybe is little operatins system depend, ijeos, ikmos or 4x4 to 2x4.

If this show some odd behaving in dwell time, then it's digging to winols and find tables what alter this dwell path and modify those maps, if not, then what, find a parameter to monitor crank trigger, if there is some odd harmonic resonances and it's crank position depend and it just is worst in crank position where cyl 6 should fire..

I will come out with all findings to this forum what i have possibility to dig out.

Thank you to be patient with me and try to solve out this kind of issues

**********************************************************************************************
drumroll......

so, with dwell table at 14v was
3.200
3.200
3.200
3.200
3.200
3.200
3.400
3.400


and ect factor of dwell table
0.930 0.938 0.953 0.961 0.969 0.977 1.000 1.000
(warm engine 1.000)

drumrolll.....

cold start was TD_CLC (time dwell calculation) at 2.8ms and......warm running at 2.1-2.2ms
what is close to stock coil max dwell reasonable 2.5ms (think factory has some safety margins removed from max values)

if that is output of dme to coils, this damn dme will cut out our coil output from some 45000v to 25000v and coil energy is only half of what we expect. and it`s not helping just to increase dwell time cause dme logic is monitoring coil charge and coil temp soit`s shit same what value over 2.2 you put to table, output is limited to that 2.2ms.

if i have right with function ramen, next monitored value should be
LV_TD_AD_ACQ_VLD and that is 0/1 because that indicate DME to reduce dwell time because of comparing it to some stock coil
saturation point.

if this is the story, there is reason for our mystery misfires what we have been struggle now for some decade.
next step is to figure out how to recalibrate that coil saturation treshold.

ps

Technical - Ignition Coil Secondary Spark Energy Comparison (N54/N55, B58 and PR)

The following is an analysis between the secondary spark energy & thermals produced by various ignition coils. Secondary spark energy is the measurement of energy released from the ignition coil during the discharge event and represents energy delivered across the spark plug gap. My test setup...

www.spoolstreet.com

 

[135boost]

stupidly much thank you car abuser for that mhd td_clc log possibility.

did some test runs with 3.200ms dwell at 14v
played again with ect factor like before but without possibility to log affect before.

1.000 --> 2.20 ms td_clc
1.200 --> 2.30 ms td_clc
1.450 --> 2.65 ms td_clc
1.550 --> 3.20 ms td_clc
1.650 --> 6.00 ms td_clc
1.800 --> 6.00 ms td_clc
1.950 --> 6.50 ms td_clc

so maybe 1.550 fix my misfire issue, i will test it and inform results.

without logging td_clc, DO NOT CHANCE much ect factor.
i did not test it with different dwell times but tuning ect factor can quite fast result 10ms dwell times and fryed coils
or IGBT overload

 

[MR-KRAKA]

Seems promising I am very interested to see the results and am impressed with your vigor on this.

I don’t want to distract you but a quick question. Do you have multispark disabled? IIRC if it’s enabled it references a different dwell table other than the main.

It looks like you have have thoroughly analyzed the FR so I assume you have done this already. I just don’t want you getting discouraged if the changes you make don’t seem to add up to the data.

 

[carabuser]

I'm sure there's other useful values when troubleshooting misfires. I'd imagine there will be a signal for knock sensor values and others for injection quantity so if you find any more I'll add them to the file.