[s-cars] VIR Driving School-Carrera GT-Misfire (longish)

Sun Nov 27 12:35:49 EST 2005

How are the wire bundles coming out of the coil pack at the back of the
head?   I've seen shorts in the wire bundles there as they get twisted
around.   You said your new coils are spliced INSIDE the coil cover, so
the remainder of the harness could have a short in it and when you R&R'd
the coil pack you twisted the harness enough to develop a short.  Not
sure if it fits with it occurring only "between turn 10 and 11 and the
hairpin turn", but might be worth a shot.

bob

> -----Original Message-----
> From: s-car-list-bounces at audifans.com 
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of 
> manuelsanchez at starpower.net
> Sent: Sunday, November 27, 2005 12:04 PM
> To: s-car-list at audifans.com
> Subject: [s-cars] VIR Driving School-Carrera GT-Misfire (longish)
> 
> 
> S-heads,
> 
> Glad the list is back up. (Sorry if this is duplicated, but it
> didn't seem to go thru the first time)
> 
> I attended the Potomac Chesepeake Chapters' VIR Driving School
> last weekend. Lots of fun of course. The big pig did rather
> well I thought. My run group consisted contained some of the
> following;
> 
> lots of VW GTi's, VR6's and 1.8t's (another group had some
> R32's that were very nice)
> Bi-turbo S4's
> V8 S-4's (an Avant in the mix as well)
> Some turbo an NA TT's
> One 4000
> A couple of C4 Corvettes
> Lots of E36 M3's from the mid to late 90's
> One Mercedes SL 55 AMG
> Acura Integra
> Mazda Miata
> 
> No UrS4/6's in my group, I while I did see one there I don't
> think it ran.
> 
> Some other exotics, Porsche Carrera GT, Nissan Skyline, Elise,
> Late Model Maserati Coupe, 
> various race prepped 911's, late model RX7's, Ford spec
> racers, Ford Cobra R 
> 
> Ms Piggy did pretty well in her group. Removing the drivers as
> variables she was able to pass more cars than not, even the SL
> 55 (although the SL would open about 6-10 car lengths on the
> straights I would catch up in the corners and actually be held
> up through the twisties). The hopped up Gti's are fast and
> quick thru the corners. 
> 
> There was a bit of what I'll call Station Wagon Prejudice
> practiced by the flaggers, as they'd give me the ol' "faster
> car behind" flag even though I just passed the various cars
> just moments before.  I was glad to be quicker than some of
> the smaller cars thru the turns, especially the uphill esses,
> my favourite part of that course.
> 
> Some general thoughts on this mostly RS2 95.5 S6 Avant,
> M3's are a tick faster rolling out of corners
> The pig is suprisingly quick through the twisties (90 mph thru
> the uphill essess,  and maybe faster with a better driver)
> Reasonable grunt on the straights, although no match for the
> brute force of the AMG SL55
> The Big Reds were worth every penny
> It's fun (mostly)having the tail end slide about in the big
> pig, especially at turn 4, the left hook. A little
> disconcerting at turn 17a the Hogpen, I need to work on that
> one some more.
> Must -- have -- more -- power
> 
> Here's a link to the track map 
> http://www.virclub.com/cms/index.php?option=com_content&task=s
> ection&id=23&Itemid=106
> 
> My instructor for this event was Jim Bauer, proud owner of a
> silver Porsche Carrera GT. I got a ride in that car for a 20
> minute session and that car was amazing. It was accelerating
> thru 115 mph a third of the way thru the back straight, Ms
> Piggy took all of the back straight to reach that speed. The
> brakes are just awesome, good thing too as the corners come up
> quick afer reaching 160 mph on the straights.  All in all the
> ride was quite memorable.  
> 
> Some guy won 5 laps as passenger in that car with Randy Pobst
> as the driver the night before at the banquet. The Carrera GT
> was on the track by itself and while I don't remember hearing
> any tire squeal when my instructor drove me around, I could
> hear those giant treads squealing when Randy Pobst was driving
> the lucky winner around. 
> 
> One strange thing that did occur however, was that I developed
> what I think was a misfire on my fourth track session. This
> misfire seemed to always occur at the same spots on the track,
> which is why I started to wonder if it was a fuel (lack there
> of) question, as one spot which is located between turn 10 and
> 11 and the hairpin turn before the back straight at the Oak
> Tree, has a very severe dip, and one theory is that someohow
> these (negative?) forces some how messed with fuel delivery. I
> have no data or gauges that would support this, but it seemed
> that the misfire was most pronounced going thru this section
> of track.  I had plenty of spots where I had my foot buried
> against the firewall where I didn't feel a miss, but in this 
> particular spot   I would feel it and feel it badly.  The 2
> variables that occured prior to the manifestation of the
> problem where:
> 
> 1. Pulled coilpack to gain access to plugs to check for
> tightness (they were tight). I did this very carefully, and
> laid the coilpack atop the fuel rail/intake manifold.
> 
> 2. Added 10 gallons of 110 Octane leaded gas (no kitties for
> the track) as I was low on fuel.  After I burned thru that
> tank, I only refilled with 93 pump gas and I still had the
> misfire/stumble.
> 
> On the street I haven't felt the misfire/stumble at all under
> full throttle, but that's only for a few seconds. Nothing like
> doing that for a full 20 miinute track session.
> 
> All 5 coils were replaced less than 6 months ago (pre-Dave
> Forgie experiiment) and the coils were spliced into the
> existing wiring under the coil pack cover using solder joints
> with heat shrink tubing to cover the joint.
> 
> If anyone has any ideas on this misfire/stumble problem I'd be
> glad to hear them.
> 
> Sorry for the long post.
> 
> -manny
> 95.5 UrS6 Avant (mostly RS2)
> 
> Mihnea Custom Chipset, Bosch 3Bar, RS2 Turbo, RS2 EM, Lucas
> Delphi Injectors, Tom and Marc FMIC, ECS Stage 2 Big Reds,
> Happersized Rear Sway Bar,John Tilden bracket, H&R 29971 S6+
> springs w/ Bilsteins, 2B Camber Plates, Forge 007 BPV, 
> Samco's,  
> 
> All of the above needed to stay in front of E36 M3's, TT's,
> Biturbo S4's, V8 S4's, Miatas, Integras, 944's (one was race
> prepped) and yes an AMG SL55 (although I can't speak for the
> quality or agressiveness of all drivers, but on that weekend
> the pig was faster)
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