Shentar
Well-Known Member
I'm super frustrated at this point. I've failed my 4th smog test.
I ran a smog test in April on the Miata. Its a 1990, so 1.6L engine. There is no EGR on these cars. Its got about 180k miles.
First test, I dropped the car off at a place 2 miles from work during my lunch break, in San Carlos, CA
Test results: https://lh5.googleusercontent.com/-7yzencBkR-g/Tj2qwYUuinI/AAAAAAAAAqw/RU-_TIeb7u4/s800/photo.JPG
Failed due to high NOx.
I replaced the catalytic converter with a new Magnaflow, CARB legal 3-way catalytic converter. I also put on a Racing Beat intake with a K&N filter.The cat that was on there was the OEM one. The next test was done, again, on a lunch break, but it was about 8 miles from work, and I did a little driving before I went there.
Test 2 results: https://lh3.googleusercontent.com/-...kY/tcZm4xJwyiY/s800/photo%2520%25282%2529.JPG
Failed due to high NOx. Everything else came down so the new cat has helped.
The guy at the 2nd test place in Redwood City said it was running lean, hence the high NOx. I installed a new O2 sensor and new spark plugs. I retested a week later in Hayward. I did the test with 91 octane gas and I did a 50 minute hard drive on the freeway beforehand. I will say after the plugs, O2 sensor, intake, and cat, the car ran really strong.
Test3 results (one week after test2):
https://lh3.googleusercontent.com/-...kc/M_wmGZU2b4k/s800/photo%2520%25281%2529.JPG
Failed due to high NOx. This time I'm a gross polluter. Nice.
The tech checked my O2 sensor and MAF and said both were fine.
Time to get serious. I ran Seafoam in the car. I filled up with 87 octane gas and put a bottle of Seafoam in the tank. I put 8oz in the intake manifold through a vaccuum line, and 8oz in the crank case. Lots of white some from carbon burning. I had the oil changed the next day. I drove through that tank of gas, and refilled with Chevron 87 octane. I took off the aftermarket intake and put the OEM box back on. I checked the timing and saw that it was set to 16 degrees BTDC. 10 degrees is stock. I reset the timing to 8 degrees before BTDC. I did a 40 minute hard drive and took it back to the place in Hayward where test3 was done.
Test4: Failed due to high NOx. He didn't do the ciomplete test because it was reading too high right away. About 1700 NOx.
so. A little e85 in the gas tank? colder spark plugs?
EDIT: to provide more data of the history since I started trying to get it smogged.
I ran a smog test in April on the Miata. Its a 1990, so 1.6L engine. There is no EGR on these cars. Its got about 180k miles.
First test, I dropped the car off at a place 2 miles from work during my lunch break, in San Carlos, CA
Test results: https://lh5.googleusercontent.com/-7yzencBkR-g/Tj2qwYUuinI/AAAAAAAAAqw/RU-_TIeb7u4/s800/photo.JPG
Failed due to high NOx.
I replaced the catalytic converter with a new Magnaflow, CARB legal 3-way catalytic converter. I also put on a Racing Beat intake with a K&N filter.The cat that was on there was the OEM one. The next test was done, again, on a lunch break, but it was about 8 miles from work, and I did a little driving before I went there.
Test 2 results: https://lh3.googleusercontent.com/-...kY/tcZm4xJwyiY/s800/photo%2520%25282%2529.JPG
Failed due to high NOx. Everything else came down so the new cat has helped.
The guy at the 2nd test place in Redwood City said it was running lean, hence the high NOx. I installed a new O2 sensor and new spark plugs. I retested a week later in Hayward. I did the test with 91 octane gas and I did a 50 minute hard drive on the freeway beforehand. I will say after the plugs, O2 sensor, intake, and cat, the car ran really strong.
Test3 results (one week after test2):
https://lh3.googleusercontent.com/-...kc/M_wmGZU2b4k/s800/photo%2520%25281%2529.JPG
Failed due to high NOx. This time I'm a gross polluter. Nice.
The tech checked my O2 sensor and MAF and said both were fine.
Time to get serious. I ran Seafoam in the car. I filled up with 87 octane gas and put a bottle of Seafoam in the tank. I put 8oz in the intake manifold through a vaccuum line, and 8oz in the crank case. Lots of white some from carbon burning. I had the oil changed the next day. I drove through that tank of gas, and refilled with Chevron 87 octane. I took off the aftermarket intake and put the OEM box back on. I checked the timing and saw that it was set to 16 degrees BTDC. 10 degrees is stock. I reset the timing to 8 degrees before BTDC. I did a 40 minute hard drive and took it back to the place in Hayward where test3 was done.
Test4: Failed due to high NOx. He didn't do the ciomplete test because it was reading too high right away. About 1700 NOx.
so. A little e85 in the gas tank? colder spark plugs?
EDIT: to provide more data of the history since I started trying to get it smogged.
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