[s-cars] re: Emissions Test Failure

[Peter Schulz]

Gary. Listers...

posted to the 20v list...may be of some help - John Larson is a mechanic
and shop owner in CA, btw.
Paul is, well - we know him more "affectionately" as Royal aka "Rings of
Torture" or RoT...he and his wife Bonnie own 1 4kq, 3 90Q20v and 1 200 20vtqw..
He's also a board member of the New England Q club and  both are instructors...


Peter Schulz
1990 CQ
1991 200 20v TQW indigo mica
1991 200 20v TQW titanium grey
Chelmsford, MA USA
peschulz at cisco.com


>Date: Tue, 24 Oct 2000 19:21:19 -0700
>From: John Larson <jdlarson at ix.netcom.com>
>X-Accept-Language: en
>To: "Audi 20V" <audi20v at rennlist.org>
>Subject: [audi20v] Re: Across My desk....
>List-Unsubscribe: <mailto:leave-audi20v-39500G at rennlist.org>
>Reply-To: John Larson <jdlarson at ix.netcom.com>
>
>Great list, Paul. There are, however, a couple of things the originator
>missed. High HCs are frequently caused by timing advanced too far. I
>realize that can be called an ignition problem, but it's one introduced
>by the hand of man and not just a system failure. On cars with
>adjustable valves, tight valves can also be a major factor in high HC
>readings, again a problem often induced by the hand of man. HTH, John
>
>Paul Royal wrote:
> >
> > The following info may come in usefull when you have failed an emissions
> > test (so I'm told.... 12RoT)
> >
> > High HC - Hydrocarbons - Indicates a misfire condition (incomplete or
> > inefficient combustion).
> >         *  Ignition problems
> >         *  Carbon deposits in combustion chamber
> >         *  Overly lean A/F mixture
> >         *  Increased camshaft overlap
> >
> > High CO - Carbon Monoxide - Indicates partially burned fuel (not enough
> > oxygen for complete combustion).
> >         *  Overly rich A/F mixture
> >         *  Dirty air filter
> >         *  High fuel pressure
> >         *  Dirty injectors
> >         *  Sluggish/inoperative Oxygen sensor
> >         *  Dirty oil
> >
> > High NOx - Oxides of Nitrogen - Indicates excessively high combustion
> > chamber temps (such as produced during detonation).  Typically highest
> > readings found during part throttle/light load on non-detonating engine.
> >         *  Clogged/inoperative EGR
> >         *  Octane of fuel too low
> >         *  Compression (cranking pressure) too high
> >
> > Things to do before going for emissions test if vehicle is modified or has
> > failed a test:
> >
> > *   Fresh oil change.
> >
> > *  New air filter (not K&N, you don't want the oil).
> >
> > *   Run Techron through 12 gallons of fuel
> >
> > *   Two to Three heat ranges hotter on spark plugs (for test period only).
> >
> > *   Set idle up to 300 RPM over Mfg. specified idle speed.
> >
> > *   Use higher octane fuel.
> >
> > *   No vacuum leaks.
> >
> > *   Set idle mixture slightly lean (too lean can increase NOx & HC).
> >
> > ---
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