1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Gross Pollluter, HIGH NOX

Old 07-06-2007, 12:02 PM
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sp4149 be sure to save your old one ECT sensor if you replace it. I replaced mine with a new Delco part and it cause problems with my car. Car thought it was colder than it really was and wouldn't run right. I reinstalled the old one and it'* been fine every since. He'* my post with the problems that occurred after I replaced mine.
Old 07-06-2007, 12:11 PM
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All of the following parts and prices also from Rock Auto (though most of this is probably available locally):

My recommendation for a T-stat would be one of these (stock 195 degree or cooler 180 degree, your preference):

STANT Part # 45848 {Premium Thermostat - 180 Degree Superstat (1 23/32" x 29/32" x 29/32")} 180 Degree; Alternate Temperature $5.77

STANT Part # 45849 {Premium Thermostat - 195 Degree Superstat (1 23/32" x 29/32" x 29/32")} 195 Degree; OE Temperature $6.25

(If you like, they can easily be drilled with a 1/8" "burp" hole...makes getting the air out of the cooling system 100x easier)

Plus you'll need one each of these to install the T-stat:

FEL-PRO Part # 35595 Thermostat gskt. $0.98
FEL-PRO Part # 35666 Thermostat seal $1.80

(I've got a whole bag of brand new seals, if you want to save $2)

May I also recommend a new radiator cap:

STANT Part # 10331 {Safety Release Vented Cap (Open or Closed System) - 16 psi (SAE Range 14-18 psi)} 16 psi Pressure Rating $4.38
Old 07-18-2007, 10:57 PM
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Default Re: Gross Pollluter, HIGH NOX

Originally Posted by sp4149
Saturday (6-23-07) I took the car for a Test Center Only smog check on a dynamometer. And if failed badly and is now registered with the state as a gross polluter. The numbers were:
Test1 15 mph 1787 rpm 13.4 % CO2 2.1 % O2 9 HC (ppm) 0.00 % CO
3125 NO (ppm) (689 MAX, 1907 Gross Polluter)
Test2 25 mph 1901 rpm 13.3 % CO2 2.2 % O2 7 HC (ppm) 0.00 % CO
1827 NO (ppm) (706 MAX, 1707 Gross Polluter)
Everything passed the visual and functional tests, including the Oxygen sensor and the EGR valve.

The previous test was two years ago at the same test center and the results were:
Test1 15 mph 1796 rpm 15.1 % CO2 0.1% O2 15 HC (ppm) 0.01 % CO
70 NO (ppm) (689 MAX)
Test2 25 mph 1725 rpm 15.0 % CO2 0.1% O2 7 HC (ppm) 0.07 % CO
47 NO (ppm ) (706 max)

After last weekends workfest at Andrew'* replacing the UIM, LIM gaskets, valve cover gaskets, oxygen sensor, serpentine belt, etc... we had found some more vacuum leaks. I fixed those with heat shrink tubing and drove the car to work. I had put fuel injector cleaner at the last fillup and decided to try getting it smogged again today on the way home. The good news is that it passed. However it was very close on HydroCarbons, NOX was virtually gone, much lower than in the test two years ago. Results are posted below:

Test1 15 mph 2030 rpm 14.6 % CO2 0.0 % O2 82 HC (ppm) 0.12% CO
3 NO (ppm)
Test2 25 mph 1917 rpm 14.6 % CO2 0.0 % O2 24 HC (ppm) 0.18 % CO
8 NO (ppm)

Test 1 HC was just under the MAX value of 84, the remaining HC and CO readings were double the average values while the formerly high NOX values were just a tiny fraction of the average values of 150ppm. Really some drastic changes in all three readings, HC, CO, and NOX, compared both to the Gross Polluter test and to the test results from two years ago.

Now I am a bit concerned about the elevated HC and CO levels. Could this be due to having disconnected the battery while working on the car and the computer reset to default values? The car probably was driven about a 100 miles before the test today. Does it take longer for the computer to optimize engine performance? This is a 95SE with a 166K miles. We cleaned up some things and I'm sure knocked a bunch of carbon, etc loose. I changed oil the next day after all the work. I wonder if I should have waited a little longer before the re-test? Will fuel system cleaner in the gas raise HC and CO levels?

Thoughts?
-sp4149
Old 07-18-2007, 11:35 PM
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Ken,

I'm not entirely clear...did you pass?

Looks like you are running a bit rich. It is certainly possible your trims haven't fully re-learned yet, even after 100 miles.
Old 07-19-2007, 02:35 AM
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Originally Posted by agrazela
Ken,

I'm not entirely clear...did you pass?

Looks like you are running a bit rich. It is certainly possible your trims haven't fully re-learned yet, even after 100 miles.
Yes it passed, barely. Hydrocarbons and Carbon Monoxide haven't been this high before since we bought the car in 95. Before today'* test they were always below Average Emissions. Although no codes were set, I wonder if maybe that one coil that had a discolored post, may be resulting in a weak or incomplete spark. But then it couldn't have been as lean as it was before if a spark plug was misfiring.

My previous Pontiac 6000STE did take awhile to adjust the engine from default settings as it traveled more miles.

-ken
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