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Location: Virginia Beach, VA
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Chris,

The MS3X spark outputs are limited to the amount of current the logic circuit of the COP draws. For twin plug, the Toyota/Denso COP has high enough impedance to be paired together on one spark output without damaging the MS3X. "xbmwguy" on this forum has been running this setup on his 930 for years without issue. The LS2 CNP coils also work without issue, which is what I have installed. There maybe other coils that will work without issue, but you will have to do some home work. Do not get MS3X confused with MS3Pro, which has more robust spark outputs.
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1977 930 Slant, MS3 EFI, Carrera intake, Twin plug, Powerhaus headers, Magnaflow muffler, Garretson intercooler, GTX3071R
Old 09-12-2018, 06:49 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
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I do not know of any ECUs on the market that will read the logic signal to advise if a coil is not firing as it would in an OEM application. There is no way of knowing other than hearing detonation if one of these COPs is not firing. Keep dwell at 2-3ms as going any higher does not yield higher output anyway, those coils run a LOT of juice at full tilt, some 5-6amps each.


What's everyone running for idle and total timing? I am at 10 idle and some 27-28 total.
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Old 09-12-2018, 06:50 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #22 (permalink)
scumbag
 
Join Date: Dec 2017
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Quote:
Originally Posted by '76 911S 3.0 View Post
The Audi COP is a 4 wire coil: Logic 5v signal, +12v, Ground, and Sensor Ground. The Denso, although having 4 terminals, are a 3 wire coil: 12v, Ground, and 5v Logic signal. The fourth terminal is for the coil confirmation signal back to the factory Toyota ECU and is not used for our purposes.

The connectors are different, but you could simply cap the Sensor Ground wires at each of your Audi coil connectors and cut off the Audi coil connector and install the Denso coil connector. The Denso connector can be found here:

https://www.bmotorsports.com/shop/product_info.php/products_id/1667

Pinout:

Pin 1: Switched +12v
Pin 2: Not Used
Pin 3: 5v Logic Trigger from ECU
Pin 4: Chassis Ground (make sure this ground is not shared with the ECU ground, the valve cover is a great spot for these grounds, I have one for each bank on each valve cover).
this is fantastic. thank you very much for the detailed response.

Quote:
Originally Posted by sp_cs View Post
Good info Jayson, many thanks indeed.

Apologies OP for the slight derail.
none required. this is totally relevant and the kind of info that helps make these decisions. if you guys had ventured off in to the phases of the moon, maybe then we could discuss derailment. lol

Quote:
Originally Posted by Raceboy View Post
VAG coils are actually very reliable. Problems arise when people use excessive dwell time on those (3+ ms, even seen 5+, sheesh) while they do not like anything over 2 ms and they give very strong spark. Their only problem is that they do not forgive stupidity.

P.S. Factory ECU's also used longish dwell times in the beginning paired with early revision coils that had them fail soon, issues have been resolved 10+ years ago.
here, i'll have to respectfully disagree. having spent several years as a VW/Audi/Porsche (water-pumpers) tech, i have very limited faith in the VAG coils. the coils on the MQB platform of engine have proven to be much more reliable, but the 20v 1.8t through FSI/TSI/TFSI coils are hot garbage.
dwell time in the factory ECU maps (and performance maps) may be to blame, but i absolutely don't trust the VAG coils. i always kept a spare or 3 in my cars.

Quote:
Originally Posted by dap930 View Post
Chris,

The MS3X spark outputs are limited to the amount of current the logic circuit of the COP draws. For twin plug, the Toyota/Denso COP has high enough impedance to be paired together on one spark output without damaging the MS3X. "xbmwguy" on this forum has been running this setup on his 930 for years without issue. The LS2 CNP coils also work without issue, which is what I have installed. There maybe other coils that will work without issue, but you will have to do some home work. Do not get MS3X confused with MS3Pro, which has more robust spark outputs.
i'm painfully aware that i don't have MS3PRO. it seemed (still does, frankly) to be massive overkill for an NA 3.0-3.2L engine running pump gas. if i were cooking up something more exotic, i'd have considered the extra expense. but anything beyond MS3X seemed to pass the point of diminishing returns for my project.
Thank you for the reference on the Densos. i'll look into xbmwguy's thread and see what i can glean.
i'm a huge fan of the d585 coils. i ran them on a BMW motor (m20 in an e30) i built and on the LS in my last M3. (hot 5.3 in an e36) packaging and aesthetics are a concern for me and that alone eliminated them from my plan.
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Old 09-12-2018, 09:59 AM
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There are two different pinouts for VAG coils, just a workd of caution.

Over this side of the pond VAG coils are widely used on 1000+ hp 4cyl engines, they work very well.
I have used them for 4 years on my 924 with 2.6liter steel sleeved 650+ hp engine. NO failures and no issues at all.
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Old 09-12-2018, 11:04 AM
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Been using 6 of the bosch Audi cop with an AEM Infinity since i put it together (maybe 6 or 7k miles ago). Not had any ignition issues. I have often considered exactly what you are about having 12 cop and not knowing that each is actually working because you might not "feel" if one of the two sparks is blowing out.
You could handle it with the wiring at the relays. Run 6 of one relay and 6 of another. Interrupt the ground or power to the relay with a toggle switch to cut out 6 at a time.
I also suspect you could trigger the CEL if a missfire is detected by the ECU. I'm not sure if MS3 is capable of doing that or not. Hell, I'm not sure if my AEM INfinity is either. Although I suspect Jayson might know.
For my simple mind though, two relays with two toggles running 6 COP is an easy way to verify it. Flip off 6 and monitor for a miss. FLip them back on and then flip off the other 6 and monitor for a miss. Flip them both off for anit-theft.
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Old 09-12-2018, 11:59 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #25 (permalink)
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Quote:
Originally Posted by Raceboy View Post
VAG coils are actually very reliable. Problems arise when people use excessive dwell time on those (3+ ms, even seen 5+, sheesh) while they do not like anything over 2 ms and they give very strong spark. Their only problem is that they do not forgive stupidity.

P.S. Factory ECU's also used longish dwell times in the beginning paired with early revision coils that had them fail soon, issues have been resolved 10+ years ago.
Thanks for posting Peeps. Real info we all appreciate.
Old 09-12-2018, 01:49 PM
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Quote:
Originally Posted by lvporschepilot View Post
……There is no way of knowing other than hearing detonation if one of these COPs is not firing.
Why will the failure of one plug to fire cause the cylinder to detonate?

Surely the whole point of twin plugs is to require less total advance than a single plug for maximum brake torque?
Old 09-12-2018, 02:04 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #27 (permalink)
scumbag
 
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Quote:
Originally Posted by Peter M View Post
Why will the failure of one plug to fire cause the cylinder to detonate?

Surely the whole point of twin plugs is to require less total advance than a single plug for maximum brake torque?
with high compression, the shapes of the head and piston dome lead to a bisected combustion chamber. twin-plugging ignites a flame front on each half of the chamber and prevents detonation. it also allows for less advance as the converging flame fronts require less time to burn the mixture than one.
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Old 09-12-2018, 04:54 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #28 (permalink)
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Yes it is a concern. But not too serious as it takes quite a bit of abusing for the knock to damage n/a engine (unlike turbocharged one where it is matter of seconds).

One easy way to test systems is to have separate power supply switches/fuses for both set of plugs and just turn off at idle and hear if engine still runs on all cylinders when on upper or lower plugs. Not the most sophisticated system but works.
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Old 09-12-2018, 07:53 PM
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