[Biturbos4] Spark Plug change interval (cold running problems)

Michael Benno mbenno at yahoo.com
Mon Dec 6 13:24:45 EST 2004

I think your problems may have more to do with cold running. I don't fully understand the cold running system on the APB, however, I have noticed my '00 APB does not drive smoothly when cold, on colder days. I notice on the first acceleration, the power cuts out (begining to buck). The cutout feels like bost is coming on and then the WG (or the bypass valves) just dumps all the pressure. I could see as this gets worse that the car would buck like yours.
I noted my 01 ABP did not do this, or at least the dump was not noticable.
Is yours an '00 or '01?
Maybe someone can explain the cold running function on the APB.
Just a thought.
Mike Benno
00 A6 2.7t 

David Lau <toomanycars at mac.com> wrote:
Now this would explain alot:
Mine misses commonly after cold start, both at idle and "just once" as 
you give some throttle to pull away. Additionally, when I complete 
light braking, as I pull up to a stoplight. - several misfires you can 
feel, then watch the tach recover as you release the brakes (lower 

Now, my plugs were replaced at the 40k service last fall and to my 
amazement, no misfires! But that lasted for maybe 10 days! Right, less 
than 500 miles, and it's missing again. It's so bad now with the cold 
weather that I can't pull out of my driveway without fear of being 
rear-ended as the thing bucks and stumbles. Yet - no CEL. Is my APR 
blocking codes? Or changing the fuel mapping to foul the plugs?

I'm planning on putting the stock ECU back in, and if it still misses, 
take it to the dealer before the warranty is out.
On Dec 6, 2004, at 9:59 AM, Keman wrote:

> You can
> go longer but you can almost sneeze at an S4 engine and it misfires 
> while
> idling. They're very sensetive to injector clogging and spark plug 
> gaps.

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