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When I tried to register my 1985 in Sumner co. Tn it would not pass the emissions test (256vs220ppm nox).The car does not or has not set any codes nor a check engine light. It only has 42,492 miles. Any suggestions on where to start, including a reconendation of a service facility in the Nashville, TN area?
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Re: 1985 emissions
Larry-----
Contrary to popular belief, emissions systems malfunctions do not always set codes. One is pretty much assured that they will do so in an OBD-II vehicle, but your 85 was made a LONG time before anyone even thought about OBD-II.
There are, of course, many things that could cause your emissions problems. Given that you have a Nox problem, the 2 things that I would check first are the EGR system functioning and the oxygen sensor. I'd just go ahead and replace the oxygen sensor; it's a maintenence item, anyway. I'd check the EGR valve for proper operation. These things often "stick" due to carbonization.
Emissions tests in these cars can be a VERY complicated business. If you're going to do any emissions systems troubleshooting and diagnosis, you really need to have a factory service manual.In Appreciation of John Hinckley -
Re: 1985 emissions
How long have you owned your 85? Reason for the question is that something could of been changed so the car is not running like it left the factory. But you are a lucky man to live so close to Gordon Killebrew who was working at the Corvette plant when your car was built. You can attend his tech class with your car and discover how it is supposed to work. He lives in Cross Plains,TN. When I get the time I want to attend to learn more about my 85 and 96 LT4. Check out his web page at www.gordonkillebrew.com. Did you know that your 85 came from the factory with a four bolt mains and forged pistons not cast? The oxygen sensor is real easy to change out. I changed mine only because of the amount miles on the car I had acccumulated, about twice the amount of miles you have on yours. I did not have a Code 13, changed the oxygen sensor because I read somewhere that it was a maint item to change after about 60K miles. Your 85 has only one in the left exhaust pipe location between the front frame and the engine. My county/city does not require emission testing, most TN county/citys don't.Comment
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Re: 1985 emissions
That seems like a very tight NOx standard.
It would help if you would provide all the gas level test results including O2 if reported and briefly explain the test procedure including test weight. Is it I/M 240 or a more abbreviated test like California's 15/25 MPH Acceleration Simulation Mode (ASM) test.
If you can scan a copy of the test report, that would be best.
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