Pontiac Sunbird won't pass Georgia Emissions test

Asked by Jul 02, 2014 at 12:13 AM about the 1992 Pontiac Sunbird 2 Dr SE Coupe

Question type: Maintenance & Repair

I have a 1992 Pontiac Sunbird with 3.1 V6, automatic trans.
It will not pass Georgia Emissions testing.  It fails
with high NOx.  I was told by local mechanic that
failing on NOx is caused by either EGR valve problem or
bad CAT.  I had a new CAT installed and when I retested
it did improve but still failed.  The engine and
car run fine.  I had a remanufactured engine installed
back in January.  At that time, the car did pass emissions.
The only thing done to it between then and now was a new
fuel pressure regulator installed because the old one died.
Now it won't pass emissions.  Do you think something went
wrong with the installation of the new fuel pressure
regulator?  Back to the EGR valve.  It is the electronic
type.  No vacuum connector.  Just a cluster of about 4 wires.
I removed it and checked for carbon build up in it or where
it mounts and all was clean which I would expect since
it is a new engine.  With EGR off I started the engine
and could feel vacuum pull from where the valve connects
to the engine and also getting exhaust from the exhaust
tube.  Is there a way to test the EGR valve itself?
I connected the wire cluster back and could not see
any change in the functioning of the valve.  As for
the emissions numbers, the allowed reading for NO ppm is 984
and I'm getting 1377.  This is only under the 25/25 Test.
Everything passes on the 50/15 Test.  I was also told by
local mechanic that even though my HC ppm is passing,
it looks low.  The allowed is 136 and reading is 6 under
the 25/25 Test.  Similar under 50/15 Test.
Also, no check engine  light.
I know this is a difficult problem.  Any ideas?

3 Answers


Apply for an exemption.


You've correctly identified the major NOx issues - Cat, and EGR. Follow this link for help on testing your EGR: http://www.aircare.ca/repinfo-ere-comptesting-10.php. But I don't think that's the problem. Check the basics: Is the fuel/air ratio correct (check your plugs) (check your fuel pressure), is your timing set correctly, and is your gas cap functioning as it should. Believe it or not, a poorly-sealed gas cap can cause a high NOx reading at the tailpipe on some cars. With the HC reading you posted, I'm thinking the car is running way too lean. That makes me suspect the fuel pump or some other fuel delivery issue - airflow sensor, MAP sensor, coolant temp sensor, clogged injector(s). All will cause high NOx and low HC.


As a simple answer, try getting there when the line is short. If you let the car sit at idle for a long time, it is less likely to pass. Also, the O2 sensor may need replacement.

Your Answer

Add photo

Related Questions


Looking for a Used Sunbird in your area?

CarGurus has 15 nationwide Sunbird listings and the tools to find you a great deal.


Search Pontiac Sunbird Questions

Pontiac Sunbird Experts

#1 skindesign
Reputation 170
#2 Tom Demyan
Tom Demyan
Reputation 120
#3 bigant420
Reputation 80
View All

Related Models For Sale

Used Pontiac Firebird
14 Great Deals out of 757 listings starting at $3,490
Used Chevrolet Camaro
351 Great Deals out of 31,305 listings starting at $2,500
Used Chevrolet Cavalier
3 Great Deals out of 985 listings starting at $695
Used Ford Mustang
692 Great Deals out of 44,965 listings starting at $750

Used Cars For Sale

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.