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Worrying about smog test results and very low local MPG (89 Integra)

89 Integra with 150,000 miles on it. 2500 RPM limit avarage yours HC(ppm) 140 20 53 CO(%) 1.00 0.1 0.4 CO2(%) 14.2 O2(%) 1.0 IDLE(800 RPM) limit avarage yours HC(ppm) 120 29 112
Reply to
Edward Huang
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If your oxygen sensor has never been replaced, I would not be surprised if it's worn out. That would explain both the emissions and the gas mileage..

Reply to
Robert Hancock

You have unburned fuel or oil in the exhaust at idle.

Most commonly caused by an ignition misfire.

Reply to
saeengineer

Any suggestion to correct the "ignition misfire"? Thanks!

Reply to
Edward Huang

=46irst you have to find out which cylinder(s) are misfiring. I'm not sure what type of equipment and experience you may have, so I won't go into specific diagnostics right now.

Replacing the spark plugs is quick and cheap. Also,with the mileage you have, I would agree that replacing the O2 sensor and PCV valve would be a good idea.

As I said, this is the most likely cause. There are others, but your readings don't indicate another fault.

Reply to
saeengineer

If you have a misfire at idle, it should be relatively obvious. Does the engine seem to buck or vibrate abnormally? Also listen at the tailpipe for any irregular coughing or puffing noises from the exhaust indicating a miss.

Reply to
Robert Hancock

~~~~~~~~~~~~~~~~~~~~~~~~~~ You are right. This did happen! I already changed spark plugs. What's my next step?

Reply to
Edward Huang

So are you saying that it did buck or vibrate and it doesn't now? Did changing the plugs make any difference?

Reply to
saeengineer

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