knock, knock! Who's there?

[Ameer Antar]

Sounds like you need to richen the mixture back to where it was. If you're
getting the ECU light on that means it retarded the ignition as much as it
could, but it was still knocking. Not a good thing... Best way to do it is
to use a CO meter to adjust the mixture, but if you're O2 sensor is OK, that
will help you find the right spot too. At idle, it should be about 40-45%
duty cycle. You can even tell just by listening to the frequency valve.

Leaning the mixture to a point does make the car feel more powerful and
responsive, but that's because you're increasing the combustion temps and
really pushing the engine to the limit. A lean mixture can easily kill an
engine, esp. turbos. So do the right thing and play it safe...

-Ameer

On 7/23/07, quattro-request at audifans.com <quattro-request at audifans.com>
wrote:
>
>
> Date: Sun, 22 Jul 2007 11:06:54 -0700 (PDT)
> From: Tess McMillan <tessmc at drizzle.com>
> Subject: Re: knock, knock! Who's there?
> To: Tony Hoffman <auditony at gmail.com>
> Cc: Quattro list <quattro at audifans.com>
> Message-ID:
>         <Pine.LNX.4.44.0707221057370.15850-100000 at cascadia.drizzle.com>
> Content-Type: TEXT/PLAIN; charset=US-ASCII
>
> Right, I remember the vacuum pump; that sound was more "Audi-sounding"
> than the knock I am experiencing now. We removed the pump from my car
> about two years ago.
>
> This knock is happening at 3800 rpm, when the engine is working hard
> (more so going uphill, for example). But I think I remember when I went in
> for my track inspection in April, they leaned me out a bit. It's been
> since about that time, maybe May or so, that I've started to notice this
> issue.
>
> And to be completely truthful, on a daily basis I'm only commuting to
> school and back and with so much schoolwork I am not getting out to do
> Italian Tune-ups on the weekend.
>
> Thank you for the education, guys!
>
> Tess
>
> On Sun, 22 Jul 2007, Tony Hoffman wrote:
>
> > And, to add to that, because it's pre-detonation, it tends to hapen
> > more at lower RPM's or where the "dynamic" compression is higher. As
> > an engine turns faster, it actually pulls in less ari per RPM. This is
> > because the valves, intake system, exhaust, etc, is not a limiting
> > factor for airflow at lower RPM's. But, that becomes an impedence at
> > higher RPM's. Which is exactly where bigger cams, bigger exhaust, high
> > flow air intake systems, ported heads, etc all come in.
> >
>
>
>
> ------------------------------
>
>