[s-cars] LS2 coil adventures part 17...

Thu Feb 10 12:27:20 PST 2011

Scott - 

Still think we just have a small misunderstanding. I'm far from saying OEM coils won't work in fact I'd bet my left compressor wheel that a new OEM setup woulda done me fine. So my point is very definitely not that LS2 is the only solution that woulda worked, just that this seems to explain why LS2 did not work before on my particular car vs a other one sitting right next to it. 

Fully agree about curiosity about logging but sadly no... I said to marc I wish I had a nice logging digital Oscope to watch waveforms under boost during the whole process. I do have a logging DMM setup somewhere but didn't occur to me to try to rig it up... And not sure if its sample speed is fast enough... Also tough to wire that up to the coils for on-road WOT pulls but prob coulda done it at tue ECU side...

JC

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John Cunningham

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On Feb 10, 2011, at 12:27, qshipq at aol.com wrote:

> 
> JC thanks for the followup.  It makes no sense to me whatsoever in light of what 3B guys are running with a dizzy and stock single coil and 12.7/13.8VRs, but in the end, I say you do what works.  Did you have a way to log the voltage and miliamps at the coils before and after the mod?  
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> That LS2 Coil is a beast, which is why I'm having a really hard time believing a 14.5V feed is the really the problem, or that a 14.5VR install is the solution.  More specifically, my bet is that 14.5 VR overcomes another problem, not solved.  I've seen ocilliscope runs of the LS2 coil with some pretty impressive gapping, but then again, I didn't pay attention to what the feed voltage was.  
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> I'm intrigued, but not sold.
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> Thanks for the details
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> Scott J
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> -----Original Message-----
> From: JC <jc at j2c3.com>
> To: qshipq at aol.com; s-car-list at audifans.com; mswanson at mswanson.com
> Sent: Thu, Feb 10, 2011 8:41 am
> Subject: RE: [s-cars] LS2 coil adventures part 17...
> 
> Scott - 
>  
> Sure we thought of that absolutely. I'd been running NGK Iridiums since I got the car and the initial problems were on a set of those that looked perfectly fine.  But just in case during the first set of swaps and diagnosis I not only tried another new set myself, but Marc tossed me a brand new set of the Bosch tri-coppers with no change. It was clearly a coil problem to start with - my OEM coils were losing it.  
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> To your comments - I'm not sure it's an "upgrade" (excepting the 14v vs 14.5v) factor as much as a maintenance issue - that my system wasn't up to snuff.  So rather than saying an upgrade "increased the level of spark" I'd say that the weak VR could not SUPPORT a proper level of spark.
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> The longer story was another tech first swapped a known good set of OEM coils in and worked fine, which is what led me to get the LS2's to try out in the first place. Ran 'em for a few weeks but had a hard miss only at high-RPM+high-boost combo (aka rarely at lower RPM boost peaks).  Then we tried all manner of harnesses and LS2 "versions" and checking connections and even adding an extra head-to-chassis ground strap before giving up.  I ended up getting some used OEM coils which were OK for the Stage 1 chipset I was using at the time, but when I started boosting over 1.5bar, once the old coils heated up I'd get classic stumbling and missing at WOT.
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> So our operating assumption now is my aged charging system couldn't support the increased current draw for the LS2's, which shouldn't be surprising given that they are by all accounts a much higher power delivery than the OEM POS/Coil system. The fact that the LS2's would only fail at highest RPM's would seem to confirm it was only at the highest current draw levels that the VR couldn't keep up. The VR I pulled out looked old and played, and might even have been from a rebuilt altnater. And the 14v vs. 14.5v might have helped a little as well.  Again - before I changed that it was 100% repeatable with any of several aftermarket setups we put on the car, and with at least 2 sets brandy new plugs. After I changed the VR it immediately worked perfectly fine and seems to be holding up (fingers crossed, knock on wood, rubbing the buddha's belly etc.)
>  
> HTH.
>  
> JC
>  
>  
> John J. Cunningham
> jc at j2c3.com
> US Mobile +1 (617) 750-5025
> China Mobile: +86 136 8175 8180
>  
> 
> From: qshipq at aol.com [mailto:qshipq at aol.com] 
> Sent: Wednesday, February 09, 2011 11:29 PM
> To: jc at j2c3.com; s-car-list at audifans.com; mswanson at mswanson.com
> Subject: Re: [s-cars] LS2 coil adventures part 17...
> 
> What spark plugs were in said motor? I'm having a hard time understanding a coil pack problem being voltage with a COP application.  Having just gone thru WOT spark dropout on a stage II chipped on my 3B motor with no real options in terms of Coils, I decided to do a spark plug swap.  Swapped used F5DPOR's in, and immediately solved the problem until the Laser iridiums arrive this coming week.
> 
> I read and get a lot of complaints on coil packs that end up being spark plug issues, mostly the crappy bosch F5DPOR's getting a burn in the electrode that is really tough to see with the naked eye - which eventually takes out said coil pack.  Can alternator upgrade increase the strength of the spark?  I suppose so, but there are plenty of 3bar chipsets I have running in S cars for years with bone stock coil packs, no change to the VR.  
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> I'm sure you guys already did/checked the plugs, but this is a tough 'fix' for me to really grasp.
> 
> But I've been known to be 'dizzy' before
> 
> Scott J
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> 
> 
> 
> -----Original Message-----
> From: JC <jc at j2c3.com>
> To: 'S-CAR list' <s-car-list at audifans.com>
> Sent: Wed, Feb 9, 2011 9:14 pm
> Subject: [s-cars] LS2 coil adventures part 17...
> 
> This a repost for folks over here who might not hit the QW... interesting
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> and happy result for me this week:
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> Recap - I tried to run the LS2 setup for a while but had a hard misfire at
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> boost most of the time, especially when the car was warm, and I'd
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> reluctantly gone back to old OEM coilpacks. But when I went to 1+ and the
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> Freescale 3.0bar MAP, the old coils just couldn't take the stress and when
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> they'd heat up they'd start to stumble and miss like crazy at WOT high
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> boost. 
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> So... Marc suggested some time ago that maybe he was sniffin' that some cars
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> that fussed over LS2 coilsets could be a little underweight in the
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> alternator/volt-reg department. Well on Sunday I finally got a new 14.5v V-R
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> popped into my 120a S6 altnater and then rocked up on Monday to EFIX HQ. 
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> A first quick ballpark test on a 1.8T setup was 100% good, and frankly I'd
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> have taken that home all day, but Marc wanted to give the LS2 a try too and
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> in the name of science I was all for it. 
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> Long story short, perfect pulls everytime, none of the hard dropout misses
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> that I had before. Now a couple days later, car is still running like a
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> dream and consistently hitting full expected boost on my 1+ chipset w/ the
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> Freescale MAP. WOOT. 
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> So... for anybody struggling w/ misfires AFTER doing a big-coil upgrade,
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> CHECK the volt-reg and alternator. 
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> Easy cheap quick fix to replace BTW, even if you drop the nuts in the belly
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> pan in the snow and ice (as long as you have extra 8mm nuts in a pile of
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> junk someplace).
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> More thumbs up to Marc for the help and support. 100% solid!
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