4x4 fails smog check - suggestions?

Hey All,

Well, arghh, if it's not one thing it's another... I just failed our
provincial smog check.

Vehicle is a 1988 Nissan Hardbody pickup, 4x4, 2.5 liter, 4 cylinder, 2
plugs per cylinder, gas engine, manual tranny.

I failed hydrocarbons (HC) at idle and nitrogen oxides (NOx) at driving
under load:

HC at idle:
Average "pass" reading: 31 ppm
Max allowable: 228 ppm
Vehicle reading: 296 ppm

NOx under load:
Average "pass" reading: 295 ppm
Max allowable: 1231 ppm
Vehicle reading: 2998 ppm

Any thoughts out there as to what I should start checking?

Thanks in advance.

Cheers,
Geoff Glave
Vancouver, Canada

On Sat, 02 Aug 2003 21:32:25 GMT, "Geoff Glave"
<[email protected]> wrote:

>Hey All,
>
>Well, arghh, if it's not one thing it's another... I just failed our
>provincial smog check.
>
>Vehicle is a 1988 Nissan Hardbody pickup, 4x4, 2.5 liter, 4 cylinder, 2
>plugs per cylinder, gas engine, manual tranny.
>
>I failed hydrocarbons (HC) at idle and nitrogen oxides (NOx) at driving
>under load:
>
>HC at idle:
>Average "pass" reading: 31 ppm
>Max allowable: 228 ppm
>Vehicle reading: 296 ppm
>
>NOx under load:
>Average "pass" reading: 295 ppm
>Max allowable: 1231 ppm
>Vehicle reading: 2998 ppm
>
>Any thoughts out there as to what I should start checking?
>
>Thanks in advance.

spark plugs and their gap.

HC at idle is due to incomplete combustion which can be due to running
rich, improper ignition timing, or just from the engine being cold.
How far and under what conditions do you drive your vehicle before
dropping it off for inspection? Did you make sure the A/C was turned
off?

NOx usually goes up from running to lean (high exhaust temp) or an EGR
problem (IIRC)

What conditions exactly are defined as "under load"?

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