I know I said I wouldn't chime in again - let me point out that a 924S is
not a VW, and it really does't matter what VW used to meet california
emission standards, that timing is controlled by the computer, there is no
mechanical timing adjustment, and that NOx does NOT come from a hot
exhaust,
it is a combustion product
"dave AKA vwdoc1" <vwdoc1@[EMAIL PROTECTED]
> wrote in message
news:a0JZi.4451$TR5.864@[EMAIL PROTECTED]
>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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