[s-cars] S6 pinging woes - the continuation

[Cody Forbes]

It is very very unlikely that the car could actually be pinging with  
no load sitting in the driveway. I'm thinking this is something else.  
Maybe piston slap (worn bores or broken skirt), maybe a broken valve  
spring, maybe something else. A light rod knock could make a noise  
like this, but after the multiple 'on boost' tests you have done it  
wouldn't be a _light_ rod knock anymore ;-).

I think a compression and leakdown test would be a good place to  
start, followed closely by draining the oil through a coffee filter  
(or a paper towel) to check for metal bits as well as cutting open the  
oil filter to look for more pieces.

Even if the problem is pre-detonation pinging by now it is very likely  
that a piston ring or a piston is damaged. In my experiance with these  
engines (I've killed a few of them running over 30psi) it seems the  
pistons are so good that they'll take the detonation for a long time  
(60 seconds added up between 30 pulls maybe) and the rings, rod  
bearings, or head gasket give up first but the piston still ends up  
with some small damage.

-Cody (mobile)

On Jul 27, 2009, at 9:29 PM, "Bares, Vittorio" <Vittorio.Bares at nuance.com 
 > wrote:

> Hi all - so here's what I've done since the last call for help:
>
>
>
> Changed Stage 3 chips out of ECU
>
> Backed out wastegate spring to stock
>
> Replaced O2 sensor
>
> Replaced FPR
>
> Replaced TPS
>
> Replaced RS2 injectors w/stock injectors (used)
>
> Replaced sparkplugs (NGK BKR7E gapped @ 0.025)
>
> Was informed that the fuel pump is already relayed
>
>
>
> Sparkplugs are consistent in color - they look like the car is running
> rich.
>
> I peered down into the cylinders via the sparkplug holes - all  
> cylinders
> had the same color (grayish green) and I saw no signs of damage.
>
>
>
> Car pings just revving in the driveway - if I get on it, as soon as I
> can hear the turbo spool, all pinging goes away - but on the way  
> there,
> there's lots of loud pinging :o!
>
>
>
> The car idles slightly rough - and I *think* I can hear some noise
> coming from the bottom end - very light, sounds like, I dunno, sounds
> like something is just slightly loose.
>
>
>
> I've thought about the coils - but I don't think this would be the
> result of a bad coil would it?
>
>
>
> Anything else I should check?
>
>
>
> Vittorio -
>
>
>
> _______________________________________________
> S-CAR-List mailing list
> http://audifans.com/mailman/listinfo/s-car-list
> http://www.audifans.com/kb/List_information