MSD Wasted Spark Question

[danmartin]

So I ran into the limit of the factory igntion on my E30 the other day at 17psi. I got massive spark blow-out. I ordered some MSD coils http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8224&N=700+400122+1003+4294925143+4294890813+115&autoview=sku. I was wondering if the low primary coil resistance is going to be any trouble for the IGBT's? Also is anyone else running these? I bought these primarily because I plan to get AEM's CDI in the near future, any input on this? Thanks guys.

[rob@vems.co.uk]

Low primary resistance shouldnt be a problem, make sure that you're running 7.5A fuses on the coil power supply as this will insure that the IGBTs dont get hurt...  The way to reduce coil current is to lower the dwell/charge time.

Rob

[danmartin]

I assume you mean 7.5A fuse for each coil? What kind of dwell times do you estimate I can run, curently I am at 2.0 ms, so I assume I can run at least that.

[danmartin]

I was also trying to figure out how to implement this. My firing order is 1-5-3-6-2-4 so coil 1 would have cylinders 1+6 coil 2 would have 5+2 and coil three would have 3+4. Would I use the dual output option in VEMS, or is that for wasted fire COP?

[rob@vems.co.uk]

You're correct in all your assumptions.
One fuse per coil 7.5A gives the IGBTs safety head room.
Keep to 2.0ms and see if you get any misfire issues at high boost - if you can find a current clamp for an oscilloscope you could measure the coil charge accurately, if we're keeping it Ghetto though the rules are: keep an eye on the coil temps when increasing dwell, watch for misfires at high load/boost when decreasing.

Pairing ignition is done with the Cylinders that are at TDC together, 1 5 3 | 6 2 4 -> 1&6 5&2 3&4

Dual out is for COPs it fires: Coil00&01, 02&03, 04&05, 06&07

[danmartin]

Okay, so the only thing I have to change in software is setting three outputs in the Ignition Outputs (02..00). Now do I just go coil 00 then 01 then 02, or since its traversed backwards go 02, 02, 00?

[Jorgen]

Hi,

The normal way to start is to configure so that the table looks like this:
02
01
00
02
01
00

In 1.0.73 you will only use the first three but there will be a day when 1.1.x is the recommended firmware for all installs and you will have to have all six configured correctly then.

The coils you ordered have parameters that seem suitable for inductive ignition as well as capacitive ignition. But with unknown coils I usually fit 5A fuses during the start and test drive as that will warn you if the dwell is far too high for the coil you use.

Jörgen

[danmartin]

Thanks for the solid info!

So to get this working first I change my h[2] table to :

h[2] =   01 00 02 01 00 02 01 00

(Since it travels from right to left)

An in megatune it should read

0      0
1      1
2      2

Is this correct?

[rob@vems.co.uk]

Almost - I think you've done a typo:


h[2] =   01 00 02 01 00 02 01 00

(Since it travels from right to left)

An in megatune it should read

0      1
1      0
2      2
------- And if you're going for the 1.1.xx proof install (and why not):
3      1
4      0
5      2

[danmartin]

Okay so our h[2] values agree, but I'm confused about the megatune part, why do the coils relate that way?

[rob@vems.co.uk]

Not sure how you mean?  With MegaTune we're restricted to how we can manipulate the data, so if its in that order internally then we're probably forced to display things like that.

Rob

[danmartin]

I meant in megatune why is the sequence
1
0
2

Does it read from the bottom value up? or bottom down? is there a shift in there? I dont get it.

[rob@vems.co.uk]

It reads from the bottom up...  You see on the Ignition outputs screen Ignition outputs in use h[2] and yours will be something like 05..00 for a six cylinder.  It starts reading from the highest number down to zero.
So using the example from earlier VEMS will read from 05 to 00 h[2] =  01 00 02 01 00 02 01 00 thus providing the pattern 2, 0, 1, 2, 0, 1

I don't know why its done this way, as it must be for computational reasons rather than usability

[danmartin]

Oh man thanks Rob it all makes perfect sense to me know lol. Thanks for being patient and answering all my questions, I got the coils in today, am going to make a mounting solution for them this weekend and wire everything up and let you know how it goes, more importantly if they are up for 1.4 bar...

[danmartin]

okay finally got the coils installed however my mega tune ended up looking like this:

05...00

00   02
01   01
02   00
03   02
04   01
05   00

the order mentioned in previous posts did't work for some reason.