Some interesting emissions data

[zyewdall]

From my 1990 Legacy wagon -- I accidentally got an emissions test done on it with the oxygen sensor unplugged, and if failed (just barely). After I figured out that we'd forgotten to plug it back in after doing some exaust work a while ago, I did the test again, and got new results (passed). Though they might be of interest to someone so I'll post them.

 

Running properly:

HC = 1.17grams/mile (2.0 limit)

CO = 11.07gpm (20 limit)

CO2 = 466gpm

Nox = 2.39gpm (3.5 limit)

 

With O2 sensor disconnected:

HC = 0.23gpm

CO = 2.52gpm

CO2 = 422gpm

Nox = 3.65gpm

 

Oddly, even running as lean as it was, it ran fine (for about 1500 miles... hope I didn't damage anything), no noticeable difference in power, good mileage (about 27 to 28mpg on the freeways at 70 to 75mph mostly). Occasional check engine light at highway speeds was all.

[Legacy777]

That is some interesting data.

 

Thanks for sharing.

[rverdoold]

 

Running properly:

HC = 1.17grams/mile (2.0 limit)

CO = 11.07gpm (20 limit)

CO2 = 466gpm

Nox = 2.39gpm (3.5 limit)

 

With O2 sensor disconnected:

HC = 0.23gpm

CO = 2.52gpm

CO2 = 422gpm

Nox = 3.65gpm

 

 

I suppose both times the engine was warm (and humidity similar). Strange, only NOx is higher (think that is what the O2 sensor is adjusting. Now curious what the values would be without the CAT in between.

[bulwnkl]

Thanks for the interesting data! Don't ever let anyone tell you that automobiles are not forced to dump fuel periodically to lower emissions (specifically, NOx).

[Gsir08]

EGR is supposed to be the key lowering factor of NOx. When exhaust gas is burned, it makes the combustion not so lean. I guess this is the main way to reduce NOx without having to add fuel, I bet still adding fuel is necessary sometimes to lower NOx.

[nipper]

It sort of makes sense. The O2 snesor is the nose so to speak for the ECU, so it knows what it is smelling.

 

It is interesting data.

 

Cars run fairly clean if well maintaned, the O2 sensor just dials things in.

 

 

nipper

[zyewdall]

I suppose both times the engine was warm (and humidity similar)

 

Yup -- both tests were within about an hour and a half of each other. (sit in line idling for about 40 minutes, go in for first test, fail, drive 2 miles back to my shop to look at it -- immediately see disconnected O2 sensor and plug it back in, go 2 miles back to E-test place, sit in line idling again for about 40 minutes, and test again

 

Now... my '97 imp has the rear O2 sensor disconnected (cable is missing entirely... oddd) and it's getting lousy gas mileage (22ish instead of 26ish in same sort of driving as the legacy) and smells of unburned gas... but it's a two O2 sensor system instead of just one, and I don't know for sure if the front one is good either.

[zyewdall]

Thanks for the interesting data! Don't ever let anyone tell you that automobiles are not forced to dump fuel periodically to lower emissions (specifically, NOx).

 

Makes me wonder what the relative value of NOx on a diesel is.... I suspect it's much higher, because those always run lean -- sometimes very lean compared to a gasoline engine (except if you overfuel them, and then you get the black smoke cloud). It'd be interetesting to run my diesel through the gasoline emissions test just to see what it said, except that as an official testing place, they probably won't do that even if I pay them for the test.

[nipper]

Yup -- both tests were within about an hour and a half of each other. (sit in line idling for about 40 minutes, go in for first test, fail, drive 2 miles back to my shop to look at it -- immediately see disconnected O2 sensor and plug it back in, go 2 miles back to E-test place, sit in line idling again for about 40 minutes, and test again

 

Now... my '97 imp has the rear O2 sensor disconnected (cable is missing entirely... oddd) and it's getting lousy gas mileage (22ish instead of 26ish in same sort of driving as the legacy) and smells of unburned gas... but it's a two O2 sensor system instead of just one, and I don't know for sure if the front one is good either.

 

 

rear just checks the effeciency of the Cat, nothing else. Gas smell can be the evao smell can be the source of the gas, or, a leaky FI hose. You should look into that a bit more. POOF can ruin ones day.

 

nipper

[nipper]

Makes me wonder what the relative value of NOx on a diesel is.... I suspect it's much higher, because those always run lean -- sometimes very lean compared to a gasoline engine (except if you overfuel them, and then you get the black smoke cloud). It'd be interetesting to run my diesel through the gasoline emissions test just to see what it said, except that as an official testing place, they probably won't do that even if I pay them for the test.

 

http://www.dieselnet.com/standards/us/ld_t2.php

 

Diesel had has issues meeting NOx and particulate, thats why they have been off the market for a while. They are sloly coming back thanks to things like computer controls, new catalysts, pee (yes pee ) and direct injection.

 

And if you are really bored

http://www.osti.gov/bridge/purl.cover.jsp;jsessionid=C1E1DB4869827A97AB1D653A1C263589?purl=/829815-D2pRKp/native/

 

click on the view documnet.

 

nipper