Findings and conclutions about misfires and ignition pulls

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
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 😛
 
Last edited:
  • Like
Reactions: Jeffman and langsbr
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

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is

cold start and cruising speeds are stft wise quite decent, small issue with STFT at loads from 90 to 130 at rpm rate
from 1800 to 3000 because fuel scalar trims are maxxed out to 2.01 in that area.

is thera a more clever solution that... hmmm.. my taughts...

KF_DRKSOLL_KORR, have a table but not sure about how to use it.
KF_FRKINST_POS, did some mods to area 90 and 120 load with 1000 to 3000 rpm, will test effect and report what happend

when thinking about logic, warm up enrichement factor is one possible place to overrun that positive STFT issue with
rescale warm engine with rescaling whole warmup enrichemet scale by 1.15 and have some 1,10-1.15 as scaling parameter on warm engine
and compensate that 1.15 in whole fuel scalar table to "buy" more room to tune.

fuel pressure is maxxed out on that area too so no room for any more there, AFR is at prox 12.5 in that area too si lean out
kould fic parameter value but on cost to reduce torque, no good.
 

carabuser

Lieutenant
Oct 2, 2019
966
1
960
0
UK
Ride
Z4 35i & 335i
Rather than fudge the calculated fuel mass you should start with some basics like getting reported load in order.

Rk_soll is the target fuel mass which is based off the target load. Your logs show 186% load at 21PSI so I'm guessing there's still problems in your tune.

You should post the bin file you're using. Might not fix your problems but can spot any errors. Fuel scalar that high is a problem and the usual cause is a bad tune.
 
  • Like
Reactions: wheela

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
we had some private conversations with carabuser and i will try IS boost request offset table.
there seems to be differences on IS and non IS because what he sent me was little different what i had in my 4x4 orginal bin.

i read long topic about carabusers tests with that boost request offset and sure it seems to affect boost target, maf, fuel scalar and quite many other things.

if it was it was stated a "VE" table where all tables is searching a calibrating value for demand it is a problematic place to do calibrations.

for sure if that is VE, it will calculate MAF from boost pressure and ve, MAF will then mess up boost target to hit some load targets and there is
for sure then involved some combustion pressure calculations too what affect ignition pulls etc..

in my tune, one of the issue seems to be fuel quantity at some 2000-3000 rpm and it`s more than obvious that because it seems to
be easier on injection window to fill fuel demand after quite sharp 3000 rpm my guess is that it`S aplace where this move to single injection mode

on fuel scalar there is visible this area where fuel demand is bigger and that must be consequence of wierd things in VE table
first huge bump with maxxed scalars to 3000, then dive to some 1.60 scalars when i assume it move to single injection mode.
still there must bee room for more fuel in lower rpm/lower boost cause injector it selves cant be even close to maxxed out so it
must be just some 3 phase injection or some fuel mass/volumetric effiency/what ever to scale that to the point where scalars is not
enough

i put one maxxecu ve table there as reference for much more normal start phase, no dips, no bumps and difference is that there is no
hidden multiplier or scarlar messing up anything.

messing up with boost request offset could fix that maxxed scalars but can escalate some other issue.

i will doo today (if there is dry enough some pulls
1200-2000 wot ->shift
1200-2500 wot ->shift
1200-3000 wot ->shift
1200-3500 wot ->shift
1200-4000 wot ->shift

with those IS boost request offset tables (latest was with flat 90 over whole table and is has values from 90 to 96
 

Attachments

  • fuel scalar.png
    fuel scalar.png
    21.9 KB · Views: 34
  • clip0947.png
    clip0947.png
    182.1 KB · Views: 25
Last edited:

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
There is those logs with IS boost request offset maps. Car run very smoothly with it.
There is still that prox 15 stft at 2500rpm level and before 3000 it's close to 0.

Sorry about my picture quality, hope you get the idea.
 

Attachments

  • 2021-11-03 18_57_28 IJE0S g25_660_v2_boost request_offset_carabuser_IS.bin.csv
    145.9 KB · Views: 13
  • 2021-11-03 19_06_46 IJE0S g25_660_v2_boost request_offset_carabuser_IS.bin.csv
    23 KB · Views: 13
  • 16359633405734161875174384110852.jpg
    16359633405734161875174384110852.jpg
    230.4 KB · Views: 33
Last edited:

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
Yes, all boost it can throw, because 2 big turbos. Wgdc is at 100% to some 4000rpm

Turbos is still 2x 54mm compressor and 0.72 ar exhausts so 1200lbs at +70% effiency
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
I's about boost treshold, it just don't spool boost.

Full boost is somewhere in 4500rpm little depending on gear but no chance to spool it in 3000rpm to much more than some 10-12 psi without playing with much retarded ignition

Like i told, this rpm range is 5000 to 8000 and whole engine, piping, turboswith +30psi target etc is to that goal.
 

RSL

Lieutenant
Aug 11, 2017
937
501
0
Are you trying to find misfires and timings pulls or tune your spool? I don't understand what are you trying to accomplish with a log WOT only 2000-3000rpm each gear 3rd-6th? It's probably spool mode most of the time. There's a lot of cam overlap whole time either way and VANOS impacts a lot of things, including MAF, fuel and boost. In or not in spool mode are very different things.

90% across the board BRO aren't "IS" values.

STFTs are the difference between calculated+scalar and what it really needs to meet AFR target based on lambda feedback.

You get one calculated fuel mass per injection. Whether it's injected over 1-3 bursts, it's still the same total amount delivered at different rates/times.
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
Sorry to show those low rpm pulls here, it's wet so no possibility to do pulls over 4500rpm.
Those pulls were to try undertand logic between 3 phase and single injection phase so it's not
Straight to this topic.

Carabuser suggested that there is something wrong with the tune causing scalars hit max and
He had issues in ignition pulls when he jerked with boost request offset.

There was on numerous tuned bins what i found straight 80 or straight 90 in boost request offset tables
So i tested those until carabuser sent me that IS table and from yesterday i have that in my bin.

And yes, you have right and i'm aware that stft is showing error between calc values and lambda targets.
Carabuser just showed that boost request offset affect those ignition pulls and fuel trims so i did tests
About effect limited here on wet road and grip issues, otherwise pulls would be to +7000
 

RSL

Lieutenant
Aug 11, 2017
937
501
0
I couldn't figure out why you were logging like that, since it was obviously on purpose. Definitely not worth the risk if it's wet.

When it's in spool mode or moving in and out if it, it adds other variables to the mix and wanted to point that out.
 

carabuser

Lieutenant
Oct 2, 2019
966
1
960
0
UK
Ride
Z4 35i & 335i
The BRO% table effects quite a few parameters. The one that I noticed recently is where the output of the BRO table is used to calculate an offset onto lambda target during spool, effectively how lean spool operates.

It does have a side effect of also increasing target load and boost but that's not the correct method for doing so. It's a bit like cutting a limb off as a way of losing weight, it works but it's not recommended.
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
oh.. some wierd side effect with prox only tune difference was IS BRO%.


first, some connection or read error on log between 4000-6200, don`t dig in to it, seems that this
do that some times, it just jump 0.2-08 sec without read data correctly.
on this pull it was smooth and that was read error, not something else.

what was interesting, no misfire to +7000rpm, minor ignition pull to +7000 so it can be some
wichcraft on that IS BRO% what affect something else causing odd behaviour.

i will do tomorrow ( if dry) more testing on it but this was first 3rd gear long pull without any
misfire, lambda jump or anything.

there is seen activated single injector charge pipe additional fuel add why stft fell to -15 value, it`s been activated at prox 3500 WOT and now because of that log blackout it jump sharp to value prox 8 but in real life trancient is smoother.

There is something what alter load target what is in map 215 and in log little over 200, and still boost target and boost is close to each other. that is something to do with IAT because boost targets are higher at higher IAT what i feel is wrong, propably logic to have constant engine output not depending on out temperature
but in tuned engines that feel backwards thinking and i could want to get rid of that feature, just straght
boost target until IAT is too high



what is there as problem still is bank difference between bank 1 and bank 2 in over 6500rpm, that can be injector issue and i will do some INPA check about injector adaptations if there is differences.
 
Last edited:

carabuser

Lieutenant
Oct 2, 2019
966
1
960
0
UK
Ride
Z4 35i & 335i
I've seen logging jump like that before. Probably a comms issue or bug in the app.

That spool does look slow though. I'm no expert on big turbos but I don't think anything should take that long to spool up.
The VANOS tables are setup for stockers so I've heard there's a lot of room for improvement on larger turbos. Any improvement should be really obvious for you as it's so slow already.
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
I have done vanos tests in spool area by some 50-60 tunes and this was prox best what it became.
That pull was with 3rd gear so it spool little later than with 4th gear.
Noticeable is that size of these turbos equal to something bigger tan single g42-1200 or gtx4202r
so treshold is a issue there

I will do some 4th gear or 5th gear pull today with log and post it here so we got compareable boost treshold ve normal dynopulls.

About BRO%, even if it's named as that, scale is rpm, % and intake cam spread? And with variables from 70 to 180.
Spread can't be compared to exhaust cam as LSA cause there min and max value is in level of prox 140 to 260, neither intake cam vs tdc, that's range is from 70 to 130 and if it's VE versus intake cam position to tdc, value differences should be much bigger than few % cause of egr effect.

For sure if variable parameter is some intake cam spread and not load it will have something to do with MAF and therefore cylinder pressure calculations.
 
Last edited:

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
raining so no 4th grar pulls over 4500 but here is some idea of boost treshold
i did small mod to ignition advance and it`s straight visible on the log, advanced 110-160 load 2500-4000 some 4-5 degrees
and loosed some 5psi boost with that.

what is not so well known ( credits goes to P33P33) fuel vice, there is spool (mode 20) or not spool (mode 2)
but in ignition, it does not follow same logic, spool or not.

ignition advance is a calc value between spool and main ignition table and there is map for that calculation.
then there is time based rule to it what is RPM depending and that is what is seen in this log.

first when start WOT acceleration it`s calc value between spool and main ignition advance table what was expected, then that last for some 4 sec and then what was not expected jump to main table even if fuel is on spool table whole time.


sidenote, did a pull on same plase with same rpm and very close to same load but ignition retarded from
that pull 4 degree, hold boost some 2 psi more whole spool area. so left it to that -2 degree on some 7-8 cells.

what i think was interesting on that pull was what carabuser noticed, wgdc was 100 to 4000rpm plus before
and with 4 degree retard in those spool area cells wgdc dropped to 80-90 level..



it was intended to test pull to 7000plus rpm but i had some .. call it more than interesting 2 lane 4x4 wheelspin with that 4th gear from 4500 to 6000 because of wet road surface.


Ps. There si logic what P33P33 discovered about iign spool
 

Attachments

  • 16361781839524929852774326523296.jpg
    16361781839524929852774326523296.jpg
    186 KB · Views: 22
Last edited:

QuestFor10s

Lurker
Apr 19, 2021
13
6
0
Chicago, IL
Ride
2011 BMW 335IS DCT
@135boost this thread is still about tracing down ignition timing corrections right? I might have found some good information for you. I'm reading through the MSD81 Specification document and it seems like there are several system which influence ignition angle.
- Traction Control: To maintain traction.
- Knock Control: To protect against knock.
- Torque Requests: Any other system can request a torque limit such as DSC, or the transmission limits.
- EGT: The DME alters ignition angle to manage EGT temperature to keep it within limits for the catalytic converter and oxygen sensors.
- Startup: We can ignore this
- Anti-Jerk: The DME alters spark retard during anti-jerk or torque jitter conditions.
(I am not confident this is an exhaustive list)

You have previously stated you have factored out TC, and Knock control so in efforts to further narrow down the source we will need to identify some variables associated with each system in order to log them and determine the source of the ignition retard. I have found a few variables of interest to you.

if IGA_DIF_SP_H_RNG == 0 then there are definitely no torque related requests to alter the ignition angle from the base ignition angle and knock control. I suspect it will be non-zero for you. If this is non-zero then there is a torque request active that you will want to then narrow down. If there is a torque request then you now need to narrow it down to EGT, Anti-Jerk/Jitter, or DSC, or Transmission.

If LV_TQ_IGA_REQ == 1 then spark retard for EGT has been requested
If LV_TQ_IGA_ACT == 1 then spark retard is active due to a torque request

I'm not sure how transient these variables are or if they are even able to be logged via MHD. These variables are updated every 10ms. To sample them without missing a transient condition we should sample at twice the update frequency, in this case 200Hz, and MHD is far too slow for that. However, hopefully this will shed new light on the topic.
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is
You are absolut right, topic is still about missfire and ignition pulls, and now with your influence too, i think we are closing in to root cause for this annoyling issue what cause these.

I'm still on the opinion that 95% of solution for these missfire and ignition pulls are just done to mask real issue and there you have it right, MHD is way too slow to monitor these kind of things. I'm proud to be in community this skilled where there is guys like you, RSL, P33P33, Carabuser, and many other.

Now what needed is to get those (and carabusers find about fuel constant) to xfd file and in my case, dry road and tempperature to + side of celsius scale.
It's fustrating tojust wait for rain to stop and obvious, it is visible in my posts where pulls stop to 4500 ..
 

135boost

Sergeant
Oct 28, 2017
250
1
140
0
Finland
Ride
135is

One pull to 7600rpm, issue is still there, but now something has cange, only 21psi boost in top andeven boost request don't
Hold to redline.
There is ignition pulls and misfire, now in bank 1 at 6900rpm and recovery at 7250 so if boost request offset change reduced boost, it just moved that in upper range of rpm range.

I check today that it's not a boost leak what drop boost level to be sure if it's tune or mechanical issue

****************************************

okay, that missing boost was a boost leak. one pressure hose has a rupture on it, fixed now and
search for reasons to misfire continue as before.


log from today pull, only to 6800 because speed -2c temp and road condition in pitch dark :-( (wuss)
few things, load is quite to the maxx and i`m not sure how to rescale it to more decent values, maybe 4bar tmap ?

misfire issue is still there, in this tune it trigs at 5700 and recover at 6100

what is interesting is that this misfire trigs at
399g/s maf on 27.5 psi boost at 5700rpm
395g/s maf on 18.5 psi boost at 6700rpm
386g/s maf on 25.6 psi boost at 5600 rpm
400g/s maf on 27.3 psi boost at 6126 rpm

so those odd ossues is quite close to 390-400 maf every single time with this tune scaling

and here is that max spool with decent ignition advance curve
3000 rpm prox 10 psi
3700 rpm prox 15 psi
4300 rpm prox 20 psi
5000 rpm prox 25 psi

i can get little better spool bur sacrifice then acceleration caused on so late timed ignition ( over 4 degree atdc)

 
Last edited:

MR-KRAKA

Specialist
May 23, 2020
85
56
0
I was just messing around with BimmerLink on and E61 I picked up. I had not realized the logging capabilities of it until now. There’s a lot of parameters in there I think you would find useful in your hunting like individual knock voltage and values, individual injector current etc. I’m not sure on the frame rates since the car isn’t roadworthy just yet but thought of you when I saw the long list available. They don’t all function since it covers a wide range of vehicles but I made sure to check those two. There’s also a calculated lobe spread value with vanos which was nice to see functional. Well worth the $30 one time fee.