now pass for HC, failed worse for NO on emissions

(newsgroup distribution corrected)

On Mon, 19 Sep 2005, john wrote:

> When i first took my dodge spirit 2.5 3 cylinder for inspection,

Well, there's your problem right there...one of your FOUR cylinders has
gone missing!

> i passed for CO but failed for NO and HC. I changed plugs, going one
> step hotter

Which plugs did you:

1) Remove?
2) Install?

> replaced my map sensor, my egr valve and tubes going to it and the map,
> my egr switch, and my gas filter (which may have been plugged as the
> white spark plugs indicated the car was running lean). I reinspected and
> now passed for HC but my NO reading went up significantly, so i now fail
> for a bigger spread. Previously i barely failed, very close to the max.
> Before i was in the 1200 range and now am in the 1900 range on NO
> reading.

Your e-mails to me have indicated that you're buying used parts. Perhaps
that used EGR valve and tube weren't such a bargain...?

Could also easily be that your combustion chambers are majorly crudded up
and you're in need -- no joke -- of an Italian Tuneup.

DS

EGR system could be in need of a manual cleanout or replacement with new
parts as applicable.

If the EGR valve was an aftermarket unit (using certain colored washers
rather than having a specifically calibrated orifice, as the factory new
part would), it can affect the EGR flow rates if the wrong washer is
installed for the size of the engine.

HC being down means the engine is running "better" (i.e., more
efficiently than before), but the higher NO would indicate an EGR system
issue (EGR puts "the combustion fire" out by recirculating the rather
inert spent exhaust gas back into the intake tract).

A clogged fuel filter can usually cause driveability issues as it
generally takes a minimum pressure for the injectors to fire. Extended
crank times are an indicator, plus a louder electric fuel pump (as it's
having to work harder). GM vehicles seem to be more prone to these
issues AND expensive repairs when it happend that way. This would
relate to FI engines, in particular.

Of course, with a feedback loop fuel system and a three-way cat
converter (HC, CO, NO), having a fresh converter can be a must too.

C-BODY

On Sat, 24 Sep 2005 22:46:33 -0500, wrote:

>EGR system could be in need of a manual cleanout or replacement with new
>parts as applicable.
>
>If the EGR valve was an aftermarket unit (using certain colored washers
>rather than having a specifically calibrated orifice, as the factory new
>part would), it can affect the EGR flow rates if the wrong washer is
>installed for the size of the engine.
>
>HC being down means the engine is running "better" (i.e., more
>efficiently than before), but the higher NO would indicate an EGR system
>issue (EGR puts "the combustion fire" out by recirculating the rather
>inert spent exhaust gas back into the intake tract).
>
>A clogged fuel filter can usually cause driveability issues as it
>generally takes a minimum pressure for the injectors to fire. Extended
>crank times are an indicator, plus a louder electric fuel pump (as it's
>having to work harder). GM vehicles seem to be more prone to these
>issues AND expensive repairs when it happend that way. This would
>relate to FI engines, in particular.
>
>Of course, with a feedback loop fuel system and a three-way cat
>converter (HC, CO, NO), having a fresh converter can be a must too.
>
>C-BODY
High NOX means combustion temps too high - which can be caused by 4
things - engine running too hot (poor cooling), running too lean,
running too much advance, or no or inadequate EGR.

Eliminate ALL of the above and you cannot have NOX problems.