[s-cars] Pinging woes 95 S6

[Bares, Vittorio]

The car is a 1995 S6 w/MRC stage 3 (RS2 version) software, RS2 EM, RS2
style Injectors (37#, slightly higher pressure), RS2 Turbo.

 

I've had the car only a few months, all work was done by PO.

 

On light throttle, lots of audible pinging - put your foot in it, and at
least the audible part goes away - pulls like a train. Of course to get
up to WOT, there are a couple of loud pings - but once boost is full on,
the pinging goes away.

 

Before the weather got warm, it would ping lightly, but now its really
bad...

 

Running 93octane from Sunoco, w/Octane boost (have used a number of
different brands - all have very little affect)

 

Have run a full tank of Techron to help the injectors, if that were the
problem. (have not changed these out)

 

Bob sent me a dumbed down version of the fuel maps and that had zero
affect, except that the car feels like a dog now, especially since I
backed the WG spring screw back to stock.

 

I can get the car to ping parked in the drive way, by just manipulating
(blipping) the throttle directly.

 

I put a new FPR in - suspecting that. No change.

 

I've looked around for ways of testing the TPS - the instructions on SJM
seem confusing - however, pins 4&6 show infinite continuity at idle,
make the switch 'click' and it goes to zero resistance. Pins 2&3 show
between 1000 and 1800 ohms resistance from zero throttle to WOT - these
seem like pretty weird numbers, and would indicate that I'd have more
trouble at WOT than at small TP angles...

 

Pulled all the plugs, they all look the same - like they were running
rich !? Although the ceramic under the electrode is a beige color -
which might indicate some heat?

 

While I had the plugs out, I inspected what I could of the top of the
pistons, they all seemed ok - appeared to have a greenish/gray color,
but seemed pretty flat and smooth.

 

I guess right now, from what I've read the list of potential culprits
could be:

-- Temp Sensor (I'm assuming this would be water, not oil)

-- Air Temp Sensor

-- Injectors (but why would they be ok at high boost WOT)

-- Knock Sensors (but why would they be ok at high boost WOT)

-- TPS

-- others?

 

Before I go buying a whole bunch of new parts I don't really need - I
thought I would reach out to the list to see what I should do first?

Vittorio -