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

Thu Feb 10 06:41:39 PST 2011

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.   

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. 

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. 

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
 <mailto:jc at j2c3.com> jc at j2c3.com
US Mobile +1 (617) 750-5025
China Mobile: +86 136 8175 8180

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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.

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

-----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

and happy result for me this week:

Recap - I tried to run the LS2 setup for a while but had a hard misfire at

boost most of the time, especially when the car was warm, and I'd

reluctantly gone back to old OEM coilpacks. But when I went to 1+ and the

Freescale 3.0bar MAP, the old coils just couldn't take the stress and when

they'd heat up they'd start to stumble and miss like crazy at WOT high

boost. 

So... Marc suggested some time ago that maybe he was sniffin' that some cars

that fussed over LS2 coilsets could be a little underweight in the

alternator/volt-reg department. Well on Sunday I finally got a new 14.5v V-R

popped into my 120a S6 altnater and then rocked up on Monday to EFIX HQ. 

A first quick ballpark test on a 1.8T setup was 100% good, and frankly I'd

have taken that home all day, but Marc wanted to give the LS2 a try too and

in the name of science I was all for it. 

Long story short, perfect pulls everytime, none of the hard dropout misses

that I had before. Now a couple days later, car is still running like a

dream and consistently hitting full expected boost on my 1+ chipset w/ the

Freescale MAP. WOOT. 

So... for anybody struggling w/ misfires AFTER doing a big-coil upgrade,

CHECK the volt-reg and alternator. 

Easy cheap quick fix to replace BTW, even if you drop the nuts in the belly

pan in the snow and ice (as long as you have extra 8mm nuts in a pile of

junk someplace).

More thumbs up to Marc for the help and support. 100% solid!

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