Failed Emissions: Plea for Help

[Tim Rogers]

William Conner <Billc@fred.net> wrote:

> My SE-R recently failed the Maryland emissions test.
<snip>
> About the test results....
> ...........MD Standard.....   ........Measured Level
> HC...........1.10.............................0.93
> CO..........20.0..............................6.55
> NOX.... .....2.30.............................3.51
> CO2.........N/A................ ...........328.85
> As you can see, the car failed NOX and was marginal on HC.

Failing NOX is usually caused by an EGR issue.  Usually in a high port motor,
the problem lies with a blocked BPT tube.  This is one of those classic (no
pun intended) maintenance items covered on SE-R.net.
You may find it in its own section, or as a cure for a "stumbling idle".
The marginal results on the HC would most likely be caused by an O2 sensor
going south but can be influenced by many factors, including being overdue for
an oil change, vacuum leaks, ignition system issues or other bad sensors (MAF,
TPS, coolant temp).
Now, off to SE-R.net with you and good luck!

Tim Rogers
-'93 NX2000 T-top
-'91 NX2000 racer-to-be
-'75 Silverado tow vehicle