Emissions Problem on my 2003 Miata

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Emissions Problem on my 2003 Miata

Postby SteveL » Wed Jun 27, 2012 6:11 pm

I am having great difficulty getting my 2003 Miata through New York State emmissions inspection. The on-board intermittent monitors for the egr, catalyst, evap system, oxy sensor ( and a couple more that I can't remember) simply will not set. In NYS, a 2003 car can have no more than two unset monitors.

When the car was new, I replaced the exhaust with a racing beat header and installed a stainless exhaust. I also have a monster flow intake. But the car has passed inspection until two years ago with that after market equipment on.

The car runs great and there are no codes found in OBD II. No check engine light. I took the car to the Mazda dealer and they had it for a week, but found nothing wrong to explain my problem. I replaced the thermostat and the engine temp sensor.

Has anyone else had this problem? Any ideas?

Thank You for reading this, Steve
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Joined: Tue Jun 26, 2012 5:11 pm

Re: Emissions Problem on my 2003 Miata

Postby Brian » Thu Jun 28, 2012 8:55 am

I asked head mechanic Rocky here if he has seen the issue and he reports: "Have had a couple of 02 Miatas computers go bad. He may have to get his computer reflashed"
Brian Goodwin
Good-Win Racing
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Location: San Diego CA

Re: Emissions Problem on my 2003 Miata

Postby SteveL » Fri Sep 28, 2012 5:14 pm

Thank you for your reply regarding my emissions control problem. Can you kindly explain what it means to have the computer "reflashed"? One of the things that I love about my Miata is that I have been able to perform all service and repair on this simple car. But reflashing computers is not something that I have heard much about. How is it done? Who does it?

I also have an old Porsche. I can unplug the Motronics computer and send it out for diagnosis and repair. Is that something that can be done with a Miata computer even if no OBD II codes show?

I'm facing another inspection next month and know that the catalyst, egr and oxygen sensor intermittent monitors have not set. The scan tool shows that the oxygen sensors are sending signals and working properly. The cat is an aftermarket/low back pressure unit that has been in the car since it was new. The car has 53,000 miles on it.

Sincerely, Steve
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Joined: Tue Jun 26, 2012 5:11 pm

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