Findings and conclutions about misfires and ignition pulls

135boost

Corporal
Oct 28, 2017
202
1
107
0
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

carabuser

Lieutenant
Oct 2, 2019
546
1
409
0
UK
Ride
Z4 35i & 335i
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?
Yes, IKM0S has a public damos.

If people know what they want then I can get them the table address for any ROM. It's just that I wouldn't want to put the time into digging through the logic to work out what's needed for something so niche that is of no benefit to my own vehicles.

The public XDF looks like it has everything you would want though. The maximum spark retard should let you choose exactly how much of a reduction you want depending on the voltage coming out of the knock sensors. I can make a logging file so the raw knock sensor voltages are visible rather than just the timing reduction output. If you have ProTool then that already lets you monitor the voltage.
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
I have a ton of damos files and fd docs heres where i got them https://www.digital-kaos.co.uk/forums/showthread.php/782616-BMW-Recent-Petrol-Damos-for-free
They all need a paid winols and iam on the free one but iam using the icmos and making the ijeos damos and translating to english. I have a pretty massive xdf if anyone would like a copy pm me i don't wanna just throw it up because its still a mess while all the hex and conversions are good there are alot of things i just find and add that need deleted because they shouldn't be messed with
 
  • Like
Reactions: wheela

nyt

Sergeant
Sep 15, 2019
316
1
277
0
Ride
2010 335xi
Yes, IKM0S has a public damos.

If people know what they want then I can get them the table address for any ROM. It's just that I wouldn't want to put the time into digging through the logic to work out what's needed for something so niche that is of no benefit to my own vehicles.

The public XDF looks like it has everything you would want though. The maximum spark retard should let you choose exactly how much of a reduction you want depending on the voltage coming out of the knock sensors. I can make a logging file so the raw knock sensor voltages are visible rather than just the timing reduction output. If you have ProTool then that already lets you monitor the voltage.

public XDF does not have everything. I've had super knock shadow codes pop up when barely any timing pulls are happening. There are other tables influencing things than the few that are available.
 

135boost

Corporal
Oct 28, 2017
202
1
107
0
Ride
135is
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.


I was suggesting that knock is now known and for sure one of limitator and too much noise is one reason to run in to emergency map whar seems to alter whole bank at the time. And yes, public xdf knock tables can be altered and indeed i have tested those with small increase and reductions, but didn't get this energency go away or didn't get rid of ignition retards. It can be that i just was too shy to mode those more.

This for sure is even more like a issue on built engines and high rpm noises from bigger piston clearance etc.. 4x4 don't reduce noise eather.
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
I was suggesting that knock is now known and for sure one of limitator and too much noise is one reason to run in to emergency map whar seems to alter whole bank at the time. And yes, public xdf knock tables can be altered and indeed i have tested those with small increase and reductions, but didn't get this energency go away or didn't get rid of ignition retards. It can be that i just was too shy to mode those more.

This for sure is even more like a issue on built engines and high rpm noises from bigger piston clearance etc.. 4x4 don't reduce noise eather.
Higher values desensitize. I think the isue is the frequency its listening for. A built motor or difrent valve train is going to be a completly difrent calibration. Iam not experienced in changing these things. In the proces of a built block and head so ive bin researching how to set up knock sensors on a standalone. The process should be the same.
 

nyt

Sergeant
Sep 15, 2019
316
1
277
0
Ride
2010 335xi
Higher values desensitize. I think the isue is the frequency its listening for. A built motor or difrent valve train is going to be a completly difrent calibration. Iam not experienced in changing these things. In the proces of a built block and head so ive bin researching how to set up knock sensors on a standalone. The process should be the same.

Generally, frequency is mostly dependent upon bore. When you close off the deck, you're transmitting directly from the cylinder wall to the block. This makes the signal a lot louder.
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
Generally, frequency is mostly dependent upon bore. When you close off the deck, you're transmitting directly from the cylinder wall to the block. This makes the signal a lot louder.
Good to know👍 does porting the head, changing the cam and valve springs have any affect on freq?
 

135boost

Corporal
Oct 28, 2017
202
1
107
0
Ride
135is
The whole issue can be like carabuser told just too noisy engine. I have tested to alter those knock tables on past but without knowledge of scaling, maybe too shy tests.

Those tables are cylinder individuals and maybe multipliciering it by 2,3 or 4 could fix this kind of issue.
After treshold window has past, it jumps to mode where that affect whole bank like on that picture with all 6 cylinder injection quantity. I have similair logs where both bank drop 30% and logs where it's only one.

I have searched that damos too, no luck
 

135boost

Corporal
Oct 28, 2017
202
1
107
0
Ride
135is
Cams affect noise too, as 4x4 transfer case .. as many other hardware.. i have double barrel shotgun setup on my too and cause it's not only noise quantity, it's frequency too, no one can determine what cause what noise vice.

That closed deck is for sure biggest noise increaser.
We should study difference on tables between M engines where there is closed from factory
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
Cams affect noise too, as 4x4 transfer case .. as many other hardware.. i have double barrel shotgun setup on my too and cause it's not only noise quantity, it's frequency too, no one can determine what cause what noise vice.

That closed deck is for sure biggest noise increaser.
We should study difference on tables between M engines where there is closed from factory
I think having a chanel set up to log the knk sensor voltage as carabuser suggestrd would be a good start. the factory calibration leaves some room to go higher for main window and pre ign. Theres preamplification tables that can be numbed up. The hysterisis of rpm and air could probably be raised to keeo from defaulting (hyterisis is included in most air and rpm axis) with the biger gradients we have at higher power. some rescaling to keep the dme from interpolating. There are other varibles that If anyone is good with can buss stuff the knock info goes out on can check out page 1958 in the continental fd. Theres is a ton of stuff in the fd about measurement windows, load dymamics, hysterisis jumps in rpm etc.. they specifically use c_fac_tra_knk to desensitize for high positive load gradients. Theres alot to wrap my head around but i think even us with the ijeos cyl 2 and 5 timing pulls on e85 can benifit aswell. The more params we can log the better. I just really looked at the fd a lil bit ago. This could be a whole thread ill post up all the knock tables soon for ijeos
 
  • Like
Reactions: 135boost and wheela

nyt

Sergeant
Sep 15, 2019
316
1
277
0
Ride
2010 335xi
I think having a chanel set up to log the knk sensor voltage as carabuser suggestrd would be a good start. the factory calibration leaves some room to go higher for main window and pre ign. Theres preamplification tables that can be numbed up. The hysterisis of rpm and air could probably be raised to keeo from defaulting (hyterisis is included in most air and rpm axis) with the biger gradients we have at higher power. some rescaling to keep the dme from interpolating. There are other varibles that If anyone is good with can buss stuff the knock info goes out on can check out page 1958 in the continental fd. Theres is a ton of stuff in the fd about measurement windows, load dymamics, hysterisis jumps in rpm etc.. they specifically use c_fac_tra_knk to desensitize for high positive load gradients. Theres alot to wrap my head around but i think even us with the ijeos cyl 2 and 5 timing pulls on e85 can benifit aswell. The more params we can log the better. I just really looked at the fd a lil bit ago. This could be a whole thread ill post up all the knock tables soon for ijeos
Can you share that doc?
 

nyt

Sergeant
Sep 15, 2019
316
1
277
0
Ride
2010 335xi
After reading through the continental msd81 docs and examining a knock sensor with a scope hooked up, I think I have some understanding of why the basic tables are ineffective beyond a certain point. The max signal level for the knock sensor is 5v, and as such, you can't set the knock threshold above that. Tapping on the sensor with a little allen key, I was able to easily generate well over 5v. That was with a very high impedance input, and I'm not sure what circuitry is on the dme, so that voltage may not all be visible there. I'm thinking adjusting the pre-amp levels to prevent the signal from being scaled too high may be the solution. It's just a theory, but should be easy enough to test.

Screenshot 2022-06-17 020056.jpg

I'm going to test some changes this weekend, essentially copying the 2496 row to the right for these tables. Will see what impact it has, if any, on the false knock.

This is also interesting:
KNKS_REL_NL[NC_CYL_NR] is the relative knocking value, it is the quotient of KNKS[NC_CYL_NR] and NL[NC_CYL_NR].

Basically, the relative knock value is the knock signal divided by the noise level. The averaging constant for noise level drops as RPMs increase. This may also be something that can be adjusted to get rid of some false knock in high noise scenarios.

Screenshot 2022-06-17 035906.jpg
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
I was hoping to have all the knock tables defined but haven't had a chance. Still have end of measurement window and begining, and max spark retard coming. And that will be everything from the continental knock stuff.

As far as the dme goes it works with the atic62 device. I have yet to find an application guide for it.
Theres a transient case for noise value to thats used when there are large positive load gradients during this mode adaptions look to be read only
 

Shitrockn54

Lurker
Apr 17, 2022
22
13
0
Ride
335xi
Does anyone else have horible timing pulls with no lift shift relay to? I dont have a way to log it but its likely that the averaging constant for noise at transient conditions is active for shift and triggered by large load gradients, effectively never trigering because of the no lift shift
 

nyt

Sergeant
Sep 15, 2019
316
1
277
0
Ride
2010 335xi
Thanks to @Shitrockn54 for defining the tables, I've managed to sort out the false knock issues, even with with built motors, in tuning.

I've posted details here, and I'm going to continue refining this.
 

135boost

Corporal
Oct 28, 2017
202
1
107
0
Ride
135is
Seems that this topic start to solve issues what never before has been solved so i feel satisfied to open it. I has been hospitalized for a week so i didn't have chance to test these new tables yet but from tomorrow on the n54 again searching solutions.....

Like this forum...
 
  • Like
Reactions: wheela

wheela

Sergeant
Jun 4, 2021
403
234
0
Twin Cities, MN
Ride
2015 e84 X1 35i Msport
Seems that this topic start to solve issues what never before has been solved so i feel satisfied to open it. I has been hospitalized for a week so i didn't have chance to test these new tables yet but from tomorrow on the n54 again searching solutions.....

Like this forum...
Sorry to hear you've been in the hospital, that's never fun. I hope you get well soon.