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    N5X Igntion coil testing, part 1

    As some of you know, the last couple months I have been helping reverse-engineer the BMW ignition system in order to help develop a path for upgrading it. The stock system isn't horrible, but it has many shortcomings as everybody who owns a high powered N54 is well aware of. That being said, since others seem to also be developing upgrades, I think I'll start releasing some information on what I've found for the benefit of the community. Unlike some other threads, this is all new information, and will be expanded and refined the next 1-2 months as testing continues.

    1) What are the hardware limitations of the DME?We'll use the older MSD80 to expand on this question. If the hardware is good, it opens up different options than if the hardware is lacking to begin with.

    Click here to enlarge

    Nearly all BMW's use TCI systems for spark (transistorized coil ignition), which means they have a transistor IGBT (also known as an ignitor) to drive an inductive coil. The transitor is located inside the DME, as opposed to some cars which have a module. The transitor used is a Fairchild ISL9V5036S3ST class IGBT, the datasheet can be downloaded here. It's a very nice transistor, capable of over 30 amps per channel and 250W heat dissipation, among other key features.

    The way the circuit functions, is you have a 5v logic signal to the IGBT in the DME. That grounds an output to the coil, energizing the coil (coil has constant 12v and a secondary ground in addition to the coil - signal). When the 5v logic signal ends, the ground path ends, and the coil fires. This is a "dumb" system since the transistor (aka ignitor/IGBT) is separate from the coil. Basically, the transistors function as the points in an old muscle car. Smart coils (LS, Audi, Honda) have the 5v logic going straight to the coilpack, which has the IGBT incorporated.

    2) What are the current ignition coils capable of? Bosch/Delphi OEM coils were used to establish a baseline, to see just how powerful the factory system is, and what the limits are for dwell time.

    The best way to test an ignition coil is with an oscilloscope. There are a few key things to be concerned with including primary coil amperage draw vs dwell time, primary coil saturation point, secondary coil peak voltage potential, and secondary coil output. Some of these measurements are more difficult to obtain that others. I am not going to release everything I have yet, others need to do their own due diligence, but here are some of my results for dwell and amperage draw that are relevant to everybody on the platform:

    a: Bench testing OEM coils. Top trace (green) is function generator signal (dwell), yellow is current draw, lower trace is high tension (secondary voltage, spark starts when primary current collapses and ends at the squiggly, better seen in lower image with upgraded coils)
    Click here to enlarge

    b: Testing OEM coils on a running car. Current draw can vary based on operating conditions but is a quick and easy way to see if the tables in the XDF are functioning as expected. In a nut shell, at the beginning of this project, they were not. Now they are, and similar to the bench testing the coils saturate around 3mS at ~14V. Note- current clamp was being finicky today and no good secondary coil data due to technical difficulties with interference (no spark plug wires makes it difficult to obtain):

    Click here to enlarge

    If you want to know the mJ output of the Bosch, it's low. The DME can handle more amperage than this, the coils were simply saturating. More will be released on this later.

    Just for fun, here's what an upgraded coil looks like on the test bench at 1, 2 and 3mS with significantly stronger secondary output:

    Click here to enlarge

    3) Is the DME hardware limited by software?Just because the hardware is good, doesn't mean BMW won't stop your fun.

    A couple people have tested the Dwell tables before and found that the car does not react as expected. This meant there were two options; go around the problem or fix the problem. Working with Jake and MHD, the Dwell tables can be made functional and at least one cause of current limiting has been resolved.

    4) Which coils should be considered for upgrades?

    The answer is always LS swap, for everything car related. Except LS are smart coils and tend to discharge early if over driven. Price, reliability, power are the players. I would love to hear opinions on what would constitute the best coil for these cars, as it seems there's a few drastically different versions coming out in the next 1-2 months.

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    This is great news for the platform! Thank you for the work you are putting in... repped on recharge

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    Looking good man! What do you think will be most beneficial when changing to LS type coils?
    Burger Motorsports
    Home of the Worlds fastest N20s, N54s, N55s, S55s, N63s, and S63s!

    It is the sole responsibility of the purchaser and installer of any BMS part to employ the correct installation techniques required to ensure the proper operation of BMS parts, and BMS disclaims any and all liability for any part failure due to improper installation or use. It is the sole responsibility of the customer to verify that the use of their vehicle and items purchased comply with federal, state and local regulations. BMS claims no legal federal, state or local certification concerning pollution controlled motor vehicles or mandated emissions requirements. BMS products labeled for use only in competition racing vehicles may only be used on competition racing vehicles operated exclusively on a closed course in conjunction with a sanctioned racing event, in accordance with all federal and state laws, and may never be operated on public roads/highways. Please click here for more information on legal requirements related to use of BMS parts.

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    This should help some of those high rpm misfires. Keep up the hard work.

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    Click here to enlarge Originally Posted by Payam@BMS Click here to enlarge
    Looking good man! What do you think will be most beneficial when changing to LS type coils?
    Not going LS specifically, but it's a good coil to compare against. There's many advantages but I feel moving away from the BMW OEM coils allows for gains in power and reliability, one less cause of misfires is a good thing.

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    Justin, we have discussed before, I have never had a single ignition related issue on the N54 outside of spark plug misfires from plugs gapped improperly, or testing plugs that were not up to the task. I find many more issues with fuel injection than spark.

    Saying all that doesn't mean the ignition system cannot be improved upon though. I look forward to what you bring to the table. You happen to tune the worlds fastest N54, who likes to test things til they break. Guess you wont have a problem really putting these to the test once done...Click here to enlarge
    Vargas Turbocharger Technologies
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    I don't fully understand the coil dynamics but love the data first approach. Dwell is just the coil charging time, right? Is the theory that the factory coils are not being charged to saturation at higher RPM?
    Burger Motorsports
    Home of the Worlds fastest N20s, N54s, N55s, N63s, S55s, and S63s!

    It is the sole responsibility of the purchaser and installer of any BMS part to employ the correct installation techniques required to ensure the proper operation of BMS parts, and BMS disclaims any and all liability for any part failure due to improper installation or use. It is the sole responsibility of the customer to verify that the use of their vehicle and items purchased comply with federal, state and local regulations. BMS claims no legal federal, state or local certification concerning pollution controlled motor vehicles or mandated emissions requirements. BMS products labeled for use only in competition racing vehicles may only be used on competition racing vehicles operated exclusively on a closed course in conjunction with a sanctioned racing event, in accordance with all federal and state laws, and may never be operated on public roads/highways. Please see http://www.burgertuning.com/emissions_info.html for more information on legal requirements related to use of BMS parts.

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    Click here to enlarge Originally Posted by Tony@VargasTurboTech Click here to enlarge
    Justin, we have discussed before, I have never had a single ignition related issue on the N54 outside of spark plug misfires from plugs gapped improperly, or testing plugs that were not up to the task. I find many more issues with fuel injection than spark.

    Saying all that doesn't mean the ignition system cannot be improved upon though. I look forward to what you bring to the table. You happen to tune the worlds fastest N54, who likes to test things til they break. Guess you wont have a problem really putting these to the test once done...Click here to enlarge
    I agree, the coils we have are sufficient given you run a tiny gap and have a fuel system in great shape. The OEM coils put out a very weak spark, but they spark multiple times in the midrange to make up for it. One issue is up top it goes back to single spark, and it's a weak spark, thus part of the high rpm misfires some encounter. A tight gap and weak coil gives you little room for error, you spend a lot of time on your car to achieve your results, and you get great power at low psi that others don't have such luck with, be it tuning, turbo or motor work. A stronger and longer spark will drastically increase the ability to ignite even poor mixtures. Also I'm just sick of these failure prone coils lol.


    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    I don't fully understand the coil dynamics but love the data first approach. Dwell is just the coil charging time, right? Is the theory that the factory coils are not being charged to saturation at higher RPM?
    Yes, dwell is coil charging time. Once it's saturated, additional time doesn't produce any more spark. But windings, magnet, inductance etc all effect how much charge you get, and how much of that charge gets transferred to the secondary coil (the one that sparks). This data actually shows there's room for a little more dwell in the OEM maps, which may help people a little bit. About .5ms more at 14v to start with would give you a little stronger spark up top even with multispark since it turns off up top. I've been testing with multispark and dynamic adjustments completely disabled so that dwell is adjustable the entire map.

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    This is the first I've heard that the N54 uses multispark, is that functionality defined in the updated xdf?

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    Click here to enlarge Originally Posted by V8Bait Click here to enlarge
    As some of you know, the last couple months I have been helping reverse-engineer the BMW ignition system in order to help develop a path for upgrading it. The stock system isn't horrible, but it has many shortcomings as everybody who owns a high powered N54 is well aware of. That being said, since others seem to also be developing upgrades, I think I'll start releasing some information on what I've found for the benefit of the community. Unlike some other threads, this is all new information, and will be expanded and refined the next 1-2 months as testing continues...

    Thanks for sharing! Very informative


    Have you tested the Rolls Royce coils or the S63 coils to see if they are any better that stock?

  11. #11
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    Click here to enlarge Originally Posted by noorj Click here to enlarge
    This is the first I've heard that the N54 uses multispark, is that functionality defined in the updated xdf?
    There's around 8-10 larger tables and even more smaller ones that define when and how the car will use multiple sparks, and some of this may get further defined. Currently, it's easiest to just disable the trickery for testing. Many modern inductive designs use multiple sparks to reduce emissions in the case of a misfire, going back to the 80s and 90s with waste spark for example. Difference is our computer can trigger multiple sparks during the power stroke, similar to how a CDI ignition works but not to that extreme.

    Click here to enlarge Originally Posted by Optigrab Click here to enlarge
    Thanks for sharing! Very informative


    Have you tested the Rolls Royce coils or the S63 coils to see if they are any better that stock?
    We're testing a handful of coils from OEM to LS truck (fancy ones with the heatsync, incompatible with our ignition system innately but a great comparison) and a few others just for curiosity, I'll check into these! Ultimately the numbers are mostly academic, how they perform and if they're reliable will be more telling in the end. As Tony said we have gotten by with OEM for years, but now that we're here with a magnifying glass we might as well find a definitive upgrade (or upgrades, there's not just one good choice).

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    Click here to enlarge Originally Posted by V8Bait Click here to enlarge
    There's around 8-10 larger tables and even more smaller ones that define when and how the car will use multiple sparks, and some of this may get further defined. Currently, it's easiest to just disable the trickery for testing. Many modern inductive designs use multiple sparks to reduce emissions in the case of a misfire, going back to the 80s and 90s with waste spark for example. Difference is our computer can trigger multiple sparks during the power stroke, similar to how a CDI ignition works but not to that extreme.



    We're testing a handful of coils from OEM to LS truck (fancy ones with the heatsync, incompatible with our ignition system innately but a great comparison) and a few others just for curiosity, I'll check into these! Ultimately the numbers are mostly academic, how they perform and if they're reliable will be more telling in the end. As Tony said we have gotten by with OEM for years, but now that we're here with a magnifying glass we might as well find a definitive upgrade (or upgrades, there's not just one good choice).
    Cool best of luck! This is the coil I was talking about it would be good to get some data about it.

    BMW# 12138657273 made by Eldor

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    Click here to enlarge Originally Posted by noorj Click here to enlarge
    This is the first I've heard that the N54 uses multispark, is that functionality defined in the updated xdf?
    they have been using multispark since atleast ms42. It's mostly an emissions feature. The reason it's not active at higher rpm is because there isn't enough time to be of value. At higher rpms the crankshaft is moving 35-40* every millisecond, with a charging time of 1ms, the second spark wouldn't fire until the Piston was well on its way down on the stroke.

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    Click here to enlarge Originally Posted by hobbit382 Click here to enlarge
    they have been using multispark since atleast ms42. It's mostly an emissions feature. The reason it's not active at higher rpm is because there isn't enough time to be of value. At higher rpms the crankshaft is moving 35-40* every millisecond, with a charging time of 1ms, the second spark wouldn't fire until the Piston was well on its way down on the stroke.
    Yeah I'm pretty familiar with multispark or ignition restrike, almost every platform on MED17 uses it. Alot of applications can still benefit from a second strike at 30*-50* after spark, considering that can still be around 20*atdc which is still only around 50% mfb

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    Click here to enlarge Originally Posted by Optigrab Click here to enlarge
    Cool best of luck! This is the coil I was talking about it would be good to get some data about it.

    BMW# 12138657273 made by Eldor
    looks as tho it's used on some 335i's already?

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    Nice
    2007 BMW 335i Sedan
    Motiv 900 W/PI, Fully Built Engine W/ VAC Stg 3 Head, Solid Mounts - Overrev Roll Cage, IC & Crashbar - Lvl 10 Trans - Revshift Flex Disk - DSS Rear Axles - M Factory LSD - Defiv Lock Down Kit - Fuel-It Stage 3 LPFP - Turner Motorsports Solid Subframe Bushings, Wheel Studs - Stoptech SS Brake Lines - DirtKurt AT Trans Cooler Bracket W/ Aubeast Trans Fittings & Setrab 25 Row Cooler
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    Click here to enlarge Originally Posted by hobbit382 Click here to enlarge
    looks as tho it's used on some 335i's already?
    I think they became bmw parts around 2015 from what i heard can say for certain though
    Rolls-Royce Ignition coil Teilenummer: 12138657273 (12 13 8657273)

    Tech. info:

    Replacement number: -
    New number: -
    Old number: -

    Comment: -

    Addition: ELDOR
    Details Class: 69
    Details Group: 1
    Number of standard: -

    Obligation to return (GW): -
    Designation of local parts:
    Index of rounding: N
    weight(Kg.): 0.260

    Packing: 1
    Count in the warehouse: 12
    Count in the container: 576


    01020304
    Click here to enlarge


    SearchRolls-Royce RR4 GhostEngine Electrical SystemIgnition coil/spark plug


    Rolls-Royce PARTS-CATALOG RR4 Ghost Ignition coil/spark plug

    Series: : RR4
    Model: : Rolls-Royce Ghost
    Body: : Lim
    Region: : ECE
    Hand: : L
    Transmission: : A
    Year/Month: : 2010/04

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    The good news is we can choose to keep multispark or disable it now, current limiting is still a concern with some coils but it's being worked out. With the potential for such a strong initial spark, it seems unnecessarily complicated to keep it around and optimize it, but testing will continue.

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    Click here to enlarge Originally Posted by V8Bait Click here to enlarge
    The good news is we can choose to keep multispark or disable it now, current limiting is still a concern with some coils but it's being worked out. With the potential for such a strong initial spark, it seems unnecessarily complicated to keep it around and optimize it, but testing will continue.
    Would it be beneficial to disable multi spark at WOT and retain multi spark for part throttle and idle?

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    Click here to enlarge

    I saw some post on the n54 FB page about using r8 coils (or something similar), have you tried or looked at those yet?

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    Click here to enlarge

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    Click here to enlarge Originally Posted by noorj Click here to enlarge
    Click here to enlarge

    I saw some post on the n54 FB page about using r8 coils (or something similar), have you tried or looked at those yet?
    Yes I've looked into these, the R8 coils perform well. Alex Fuller (don't know his name here) is developing a kit that uses them so questions about it should be directed towards him. The r8 coil is grouped with other smart coils like the LS, which our car cannot drive without either modifying the internal circuitry or using a custom adapter, things I'm not interested in although very cool in concept. I'm relatively certain he is using an adapter, in which case the r8 will perform well, as trying to drive them directly off the DME (while possible) is absolutely NOT a good idea. In fact it could be dangerous with some smart coils like the LS so I really hope Omar's post didn't entice anyone to splice in random smart coils lol.

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    Click here to enlarge Originally Posted by ninjacoupe Click here to enlarge
    Would it be beneficial to disable multi spark at WOT and retain multi spark for part throttle and idle?
    Beneficial? Sure! Practical? Questionable. I'd love to retain multispark, for now it's on the back burner, similar to primary cats in race cars. Beneficial if you can have your cake and eat it too ;-)

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