B58 Ignition Coil conversion (M5X) Dwell settings

[Dj Buttchug]

School me on technicals as I am uncertain how to interpolate this graph into my LINK ECU. Obviously I would like to find and load the correct settings. Does anyone have any experience with this? It seems to me it is a fairly newer modification and there is not much detail as to how to set this up correctly. I want to run the updated coils simply because they are cheap, more powerful, much newer and they can handle the demand of FI far better than OEM Bremi coils.I am doing this modification to get the most efficiency out of my engine and because I have ran into several builds documenting issues with spark delivery at high RPM high boost combos.

I have searched for hours and found guys using this conversion saying the dwell settings for the Bremi bolt down coils will function the B58 coils with no issue. I find this very hard to believe as the ignition coils that are 20 some years old have nearly nothing in common with the newer technology.

I have purchased the conversion plates and harness plugs from this company : https://www.facebook.com/tunertechllc/

After some research I found this which gives some detail on what the settings are (or could be) I cannot confirm with any additional info that this is actually correct.

https://www.spoolstreet.com/threads/b58-coil-pack-data-dwell-times.7716/

Discuss.

[varg]

Figuring out dwell time, you measure the current as you vary dwell times at different voltages to target a primary current that matches the published spec. If you don't have a published spec you measure temperatures and hope for the best. Measuring spark energy and voltage is a little more difficult, but the best possible way. You may find because of the characteristics of the coil that you see a drop in secondary voltage or spark energy past a certain dwell point, even with the primary current within spec. Coils are still coils, it's just down to them having more refined windings and cores, and what is economical for mass production.

Top down view, the numbers in the map you posted look reasonable, they're very similar to M50 numbers from the OE DME tables. Unless someone else has done the legwork for you and posts their tables or bosch has published a datasheet for their B58 coils (maybe email them?), there's one way to find out for sure:

http://www.dtec.net.au/Ignition%20Coil%20Dwell%20Calibration.htm

A verified map from a Supra ECU is the next best thing I suppose, but you don't know what modifiers are applied to that dwell number unless you can dig through the software yourself. It's always possible that the numbers you see in the table are subject to some other modifiers and that the actual dwell under boost or cruising is different from what you'd get just reading that one table.

[Dj Buttchug]

^ That was a good read. I also found this digging around some more. I am confused on the multi spark table to right in this article. I would assume I would use the values on the left side table.

B58 Ignition Coil Conversion - MS4X Wiki

[Panici]

Couple posts (Number 451 and 452) from my build thread. This is with stock M52B28 coils and Quadspark modules.
Not sure if it applies at all to B58 coils.

Table I used was from Haltech's website.
https://support.haltech.com/portal/e...les/m52-engine
I went with a base dwell of 3ms and my own multiplier table to be conservative.

If that old forum post is to be believed, it looks like the original ECU dwells the coils longer then 3ms (until 7000rpm) so I am satisfied I won't burn out my coilpacks with my numbers.





And an old forum post for more reference info:
https://www.bimmerforums.com/forum/s...il-dwell-table

For what it's worth, here's the dwell table from MS41.2 for the S52.



MS41.0/.1 on the M52 uses the same physical configuration, so probably the same, but nobody has added the address to the ECU definitions so I can't be sure.

Hard to compare between different ECUs, but with these settings, stock (Edit: and original from 1997) Bremi coils, BKR7E gapped to 0.020", I get some breakup under boost at higher RPM and 10-14psi.

[Dj Buttchug]

Thanks Panici! I too stumbled on that thread looking for Bremi OEM coils for m5x just to compare what I am running in LINK to stock.

I found these tables to be interesting. Post claims these are stock DME settings.



Here is my current table with Bremi coils. Note (not one single issue with coils so far) This is the table that comes in the G4X e36 base map plug in from Link ECU.

After doing some more reading I found that operating MS @ 14v should be 3.5 or under... Still no hard info on B58 coil dwell other than what has been posted above. I did find one guy on youtube claiming the 413 red label DME settings for dwell will run b58 coils fine as they are " close enough"
Not sure how I feel about that.



Varg,

What does your table look like?

[Panici]

After doing some more reading I found that operating MS @ 14v should be 3.5 or under... Still no hard info on B58 coil dwell other than what has been posted above. I did find one guy on youtube claiming the 413 red label DME settings for dwell will run b58 coils fine as they are " close enough"
Not sure how I feel about that.

Good to hear about 3.5ms being the limit, I have a little headroom.
Mine are 3ms @ 14v and have no issues yet (granted I'm still running low boost).

[Dj Buttchug]

I may just trial and error b58 coils at these settings and see how it works out. I have all the parts now just wasnt too excited about chopping up my harness and have it not work out.

[varg]

I'm going to learn from your experience either way. So far I've reached 15psi of boost and I don't have any issues with misfires on my M50B30 with stock Bosch coils and 0.02" gapped plugs, but I may yet. I am still pretty much on my base ignition map and there's always a chance that it misses with more advance.

[Dj Buttchug]

No updates on this yet as I have not committed to cutting my harness up. Will report once I do finish it.

[Northern]

^ That was a good read. I also found this digging around some more. I am confused on the multi spark table to right in this article. I would assume I would use the values on the left side table.

B58 Ignition Coil Conversion - MS4X Wiki

Honestly I have been confused about this for years.
The way it's written makes it look more confusing than it should be, you could easily think left vs right tables could be MS42/43 bolt-in coils vs MS45 pencil coils, or MS42 vs MS43.

I think from the text above that, MS43 can do multispark? Not like multiple plugs per cylinder lol, but multiple ignition events per combustion event?
Seems weird, but I guess it's a thing, and what the second column with the weird values is for.

So first column is what you'd use for a 2D table like on MS41. Once you bring in engine speed, I'm lost though.

[Dj Buttchug]

Diving into the coil swap last night and into this morning I was able to get the stock harness modified to accept the new plugs for the coils.


I dont know for sure if this is needed but I built a ground harness that bridges both coil mount plates together to ensure the ground was strong on each bank. Probably a bit over kill but better safe than sorry.
Here is the dwell chart I am running. This comes from the above discussion about what to use for settings... The car starts, runs and the new coils do not overheat or behave in any odd way so far. I am sure these will need adjusting later. I am hoping for now they are safe to use until I can confirm more information on the subject.



Here is a shot of the final product. There is no way to completely install new wires into the existing harness. You have to cut somewhere (which sucks) I went for the cleanest possible way that is easy to access if there is an issue later on. Wiring was connected using solder in the smallest portions possible. Proper sized shrink tubing should insulate the wires well enough to prevent any noise issues. The cut and splice was the worst of my worries in doing this which is why I put the project off for so long.

It will be interesting to see how the new coil work out. The factory beauty cover fits over them as normal. If anyone has new info and/or constructive comments to add please do so.

[varg]

The angle of the connectors makes me wonder if my stainless coil cover would fit with these coils. I just started getting a misfire at high rpm under boost. I need to pull my plugs and check gap and condition but I suspect I'm soon going to find the limits of stock coils. I like the version of the kit that puts the connectors on the intake side since I already can't fit the coil wire guide under my coil cover.

[Dj Buttchug]

The stock cover fits with no issues but a stainless cover may sit lower. I should mention too I have my spark plugs gapped at .024 adjusted down from .035. I do not have any misfire issues @ the lower boost settings of 7psi nor did I have any with the stock bremi coils and a .035 gap on the plugs.