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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Mon Jul 09, 2018 4:04 pm 
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Joined: Tue Aug 02, 2011 2:05 am
Posts: 33
Location: The Netherlands
ECU Model: S60 Pro
Firmware Version: 63
stevieturbo wrote:
So even with only 1 coil and 1 plug/cyl in use, it still does not rev or perform correctly ?

Yes it does! On just 1 coil and 1 plug connected, it runs fine under boost and rev over 8K no problem!

Quote:
Are you sure tuning is good, and it isnt crazy rich or something ?

Thought it might be, but with closed loop working again, it should be ok on fuelling. Log showed a little bit too rich atm, but that was never a problem before.

Quote:
What dwell time are you running on the coil ?

Can you try an OEM Ford coil ?

Plug gap ?

3500ms
yes, but I only have one OEM Ford coil...
Gapped at 0,60mm atm (original was 0,7).
Quote:
All engine grounds good ? Likewise any power feeds to the coil ?

I think, but do we ever know for sure hey?

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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Mon Jul 09, 2018 5:43 pm 
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Joined: Mon Jan 16, 2012 1:39 pm
Posts: 80
ECU Model: S40 Pro
Firmware Version: 58
msd says for that ford coil to use 3000 ms dwell max

also 0.60 gap it fine for that kind of coil, its a powerfull coil that i use it with 0.80 gap...


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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 1:01 am 
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Joined: Tue Aug 02, 2011 2:05 am
Posts: 33
Location: The Netherlands
ECU Model: S60 Pro
Firmware Version: 63
iceman_n wrote:
msd says for that ford coil to use 3000 ms dwell max

also 0.60 gap it fine for that kind of coil, its a powerfull coil that i use it with 0.80 gap...

Thanks for that! I'll reduce dwell to 3000ms.

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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 3:22 am 
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Joined: Fri Feb 28, 2014 1:03 pm
Posts: 1137
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79
From what you've said, all the set up is correct. Nothing obviously wrong.


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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 4:21 am 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2913
Location: Norn Iron
ECU Model: No ECU
I would verify that your AFR readings are correct...ie 2nd opinion, and also how are you reading this ?

via the devices own gauge, or via some analogue output to another reader ( ie ecu ) ? Have you ensured these are all calibrated correctly ?

With 2 plugs per cyl, I'd expect you to need less overall timing because burn rates are faster...are you using same tuning with 2 sparks ?

Do you have access to an oscilloscope and current clamp ? That way you can determine the sort of dwell you need to run for the coil.

TBH....I like OEM coils ! But if lots of people are using the MSD they should work

Have you tried one coil pack on one set of plugs...find a combo that works, then try solely the other set ? To test if all individual parts actually work ?

I wouldnt see a problem with 0.6mm....do you have any leads criss crossing, or are they all kept apart from each other ? Although I doubt crossfire or interference is the problem ?

And are you sure firing pairs are the same ? on one coil can you swap the pairs about ? As wasted fires a pos/neg spark on each end...I wonder if you had an opposite pair occurring on the same cylinder would that create problems ?


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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 5:18 am 
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Joined: Thu Jul 28, 2011 4:10 am
Posts: 871
ECU Model: S100 Pro
'With 2 plugs per cyl, I'd expect you to need less overall timing because burn rates are faster...are you using same tuning with 2 sparks ?'

I was thinking this, I recall a test on a Pinto with twin plugs and they found that with 2 plugs running the max advance needed reducing something like 13 to 15 degrees.
So perhaps the misfire is from the massively over advance with both plugs firing. A quick way of trying this would be to use a switch and map2 to access different ignition curve whilst driving?


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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 9:18 am 
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Joined: Tue Aug 02, 2011 2:05 am
Posts: 33
Location: The Netherlands
ECU Model: S60 Pro
Firmware Version: 63
Rob Stevens wrote:
'With 2 plugs per cyl, I'd expect you to need less overall timing because burn rates are faster...are you using same tuning with 2 sparks ?'


You are correct! The same in this case, I have reduced timing already about 4 degrees (retarded) with respect to single plug operation. As I have a 98mm bore, twin-spark really can make a difference I think.
Even more reduction of timing and I am afraid of too high EGT's...

Still, even so, suppose my timing was still too aggressive for twin-spark operation, wouldn't that just lead to knock? In stead of blow-out? Or can too much advance cause blow-out as well?

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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 9:24 am 
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Joined: Tue Aug 02, 2011 2:05 am
Posts: 33
Location: The Netherlands
ECU Model: S60 Pro
Firmware Version: 63
stevieturbo wrote:
I would verify that your AFR readings are correct...ie 2nd opinion, and also how are you reading this ?

via the devices own gauge, or via some analogue output to another reader ( ie ecu ) ? Have you ensured these are all calibrated correctly ?

I use an Innovate MTX-L set with a direct (wide band) feed to the ecu.
Its calibrated twice already, but yeah, the device could be faulty as well.

Also one of the MSD coilos could be faulty. At just 80 dollars or so, I have had my doubts if its a quality product...
Maybe also try my one OEM coil instead of one of the MSD's and see if that solves anything.


Quote:
And are you sure firing pairs are the same ? on one coil can you swap the pairs about ? As wasted fires a pos/neg spark on each end...I wonder if you had an opposite pair occurring on the same cylinder would that create problems ?

No, not sure. I can only try changing out wires on one pair.
Its just 4 pairs to try out ;)

Thanks @all for thinking with me on this one!

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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 10:04 am 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2913
Location: Norn Iron
ECU Model: No ECU
So you have verified when you see 1.0volts out of teh MTX...you see 1.0 volts on the ecu ?

Likewise, 2, 3, 4, 5 ?

That is what needs calibrating.

And ensure you're using a range that allows you to see say from 9.0 to whatever lean you choose.

Some of those shitty gauges only read down to 10.0, and people use the built in calibrations when hooking to an ecu...so you'd never know if it is 10.0...or 9...or 8....except the damn thing wont run and will miss under load or fail to rev etc. But at 10.0..well, it's rich, but not terrible ? Dont want to risk leaning it out when it's already running badly.

I would be trying an OEM coil first anyway ( proper OEM, not generic replacement )

And you shouldnt need to swap much...I assume each pair of coils are exactly mirrored ? ie so firing polarities will be the same ?

What if you try delaying one coil packs firing by say 1-2deg ? Small enough number it shouldnt affect performance...but might affect something ?


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 Post subject: Re: Twin-spark misfires under boost - ECU power?
PostPosted: Tue Jul 10, 2018 10:23 am 
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Joined: Thu Jul 28, 2011 4:10 am
Posts: 871
ECU Model: S100 Pro
I don't think a +ve or -ve spark is going to make much odds this side of an F1 team :) :)


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