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

[JC]

cue Led Zep Communication Breakdown.  Scott I think I said every time - I
think it is most likely that my old VR was crapped out, and that the 14.5v
may or may not have been really the difference.

so picture if you will, a really nasty worn out bad-brushes ratty failing
terrible generic Voltage Regulator from a cheapo alternator rebuild.  I mean
a real nasty piece of worn out shit (that's what I took outa there). forget
for a moment about 14/14.5v. imagine you never even heard about that.
expunge it from your mind. then imagine this complete worn out brushes piece
of crap being installed in my car and not operating properly.  that is our
primary hypothesis. and rather than continuing to obsess over the 14.5 vs
14.0 imagine that at high demands, the beater old VR maybe could barely
deliver CURRENT to keep voltage up to OEM levels. if the old dead beater VR
was not delivering enuff current at high RPM then subsequent voltage drop
would be a symptom rather than a cause.  then imagine that we toss the LS2's
in and they want even more charging current than OEM coils.  we now submerge
below the barely-adequate current capacity of the old worn out VR, not
enough electrons are available to fully charge the coils at high RPM, and we
get weakened spark output. in fact I hadn't made the connection until now,
but I definitely think I had much worse stumbling at night w/ lights on so
that would hint that my charging system was a factor at higher loads.
obviously we didn't get any on-road logging which woulda been great.

your battery suggestion is interesting as well, the battery is only a couple
years old but yes we coulda strapped a new one in to see if that helped.
however, as Marc said - I suspect that at high frequencies (RPM) the battery
is less able to supply momentary AC-like current demands (charging pulses
during dwell points) and relies on the alternator to keep the supply "stiff"
as we say in electronics world.  but woulda been interesting to test a big
fat new battery and see if it helped. if I didn't have 100 things to do we
could get all scientific on it but I just hafta be pleased with outcomes at
this point.

BTW a bit of quick interwebbing suggests the various LS1/2 coils require in
the range of 7-11amps to charge, and at high RPM's the system would have
little recovery time between cylinder firing.  I also find some references
(as we all know, the LS coils are popular all over the place on all brands
of motors) to them having trouble on cars with weak charging systems, and
that was only with about 5 minutes googlosearching... I'm betting theres
some more info out there.

still totally agree w/ your comments re: testing and measuring, ABSOLUTELY
right it would have been great to measure this on car before/after. but as
Marc said, we dint but the results speak for themselves.





John J. Cunningham
jc at j2c3.com
US Mobile +1 (617) 750-5025
China Mobile: +86 136 8175 8180


> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of qshipq at aol.com
> Sent: Friday, February 11, 2011 9:47 AM
> To: mswanson at mswanson.com
> Cc: s-car-list at audifans.com; jc at j2c3.com
> Subject: Re: [s-cars] LS2 coil adventures part 17...
>
> I'm just of the thinking that this VR masked a different
> problem, as I understand spark ignition to work.  Plenty of
> other marques using less than 14.5v LS2 under boost.  When
> was the last time JC put in and/or tested his battery?  And
> I've done hesitation diagnostics, but never thought to solve
> them with a VR.  Hence intrigued.  That said, I have never
> had to use that 'fix' either.  Not many LS2 coil experiences tho.
>
> Here's hoping it really was the problem
>
> Cheers
>
> SJ
>
>
>
>
>
>
> -----Original Message-----
> From: Marc Swanson <mswanson at mswanson.com>
> To: qshipq at aol.com
> Cc: jc at j2c3.com; s-car-list at audifans.com
> Sent: Fri, Feb 11, 2011 8:28 am
> Subject: Re: LS2 coil adventures part 17...
>
>
> On 2/11/2011 9:16 AM, qshipq at aol.com wrote:
> > Isn't that a better primarily a function of spark plug gap?  SAE >
> > 2001-01-0245.  This is where some before and after measures
> would have
> > > helped.  I look at a 5ms LS2 coil at full charge,
>
> "full charge" changes after every spark event, so in the
> milliseconds between events where the input voltage is
> dropping your available spark energy is also dropping.  If I
> had more time to play I'd be happy to hookup my scope to the
> input power lines to show what happens to the line voltage,
> but I don't.  If I let everything be a science experiment I'd
> have no time to get real work done ;)  It was broke, we
> changed one variable and it fixed it.  thats scientific
> enough for me.
>
> > and think a VR of 13.7 vs 14.5 isn't going to affect charge
> time much > at all.  Put another way, that's such a small
> change, I'd be concerned > that with any increase in spark
> gap, the 'problem' comes back.
> >
> > My point being, I believe there is another underlying
> problem if a .7v > increase in VR rids one of ignition
> hesitation.  Not trying to bust > yer balls, just massively
> intrigued by this logic train.
> >
> > SJ
> >
>
>
>
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