I have seen some VWs that had EGR valves but were only designed for the CA
state emissions. I rarely see these VWs with EGRs but I do from time to
time. ;-)
Only the OP can find out if this engine might have one. I doubt it has
one,
but it is good to check anyway.
It also indicates over-advanced ign timing and/or an engine that is too
hot.
Could the engine be clogged with deposits on the intake valves? Maybe a
good long run with some Sea-Foam in the gas tank or other cleaning agent.
Doesn't NOx come from an exhaust that is just too hot, along with other
factors?
Maybe if the cleaning of the intake valves and pistons don't work then
maybe
reducing the engine temperature. I think the OP said that the engine was
running warmer than normal.
Hmmm maybe water injection. <g>
http://autos.yahoo.com/maintain/repairqa/exhaust_muffler/ques078_0.html
Oxides Of Nitrogen (nox)
Nitrogen makes up about 78% of the air we breathe. Though normally inert
and
not directly involved in the combustion process, combustion temperatures
above 2500 degrees F cause nitrogen and oxygen to combine and form various
compounds called "oxides of nitrogen," which is abbreviated NOX. This
mostly
occurs when the engine is under load and the throttle is open wide.
On 1981 and later engines with computerized engine controls, a special
"three-way" catalytic converter is used to reduce NOX in the exhaust. The
first chamber of the converter contains a special "reduction" catalyst
that
breaks NOX down into oxygen and nitrogen. The second chamber contains the
"oxidation" catalyst that reburns CO and HC.
I'm still learning this stuff!
--
later,
dave
(One out of many daves)
"William Noble" <nobody@[EMAIL PROTECTED]
> wrote in message
news:47368469$0$26406$88260bb3@[EMAIL PROTECTED]
> unless the 924 is really unusual, there is no egr valve and no egr
> solenoid
> every 944 I've looked at, and it's several, is the same as far as
absense
> of egr. I'm not going to chime in on this again, the OP can take my
> advise or leave it, it's worked on any number of cars, but they were all
> 44 not 24 - make the special tool, and turn the switch in the computer
to
> the more retarded position
>
>
> "dave AKA vwdoc1" <vwdoc1@[EMAIL PROTECTED]
> wrote in message
> news:hLkZi.68072$YL5.28731@[EMAIL PROTECTED]
>> http://www.aa1car.com/library/2000/ic60032.htm
>> Harder to diagnose are elevated oxides of nitrogen (NOX) emissions.
>> Causes here may include a defective EGR valve, EGR vacuum solenoid or
>> motor, plugged EGR ****ts in the manifold, over-advanced ignition timing
>> or engine overheating.
>>
>> read here too http://www.car-forums.com/s9/t2590.html
>>
>> "William Noble" <nobody@[EMAIL PROTECTED]
> wrote in message
>> news:47354bce$0$16722$88260bb3@[EMAIL PROTECTED]
>>> let me try saying this again - NOX is not an O2 sensor issue - it's
>>> timing related, retarding the timing will fix the problem, just flip
the
>>> switch to the retarded position
>>> <alordofchaos@[EMAIL PROTECTED]
> wrote in message
>>> news:1194622362.849083.18620@[EMAIL PROTECTED]
>>>> On Nov 7, 7:29 pm, "ignatz" <bobthea...@[EMAIL PROTECTED]
> wrote:
>>>>> Hi ! Can anyone out there help me on NOx readings on my 924S? Just
>>>>> barely
>>>>> passed a year ago - now 1850 where max. is 1250- runs great - maybe
>>>>> just a
>>>>> little hot - any ideas are appreciated. It is driven about 2000
miles
>>>>> a
>>>>> month, so not from disuse. thanx, ignatz
>>>>
>>>> It could be 02 sensor running the car lean - they're a 30k miles
>>>> service item.
>>>>
>>>> Make sure your exhaust is hot when you test... running an hour on the
>>>> highway right before testing might help the cat. You might also want
>>>> to make sure your cat is OK, not plugged, etc
>>>>
>>>> Could also be a vacuum leak causing a lean condition.
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