Well, this is my story, buy a honda civic 98 car for 3 weeks ago, had the light on the "CEL" he made ​​the diagnosis by computer and came out the code p0141 (oxygen sensor after the cat), I change but hoping to improve mpg but I've done my tests and I yields about 40 mpg for every 2.7 gallons (10 liters), the car still not made ​​any tuneup, but I would like to know of his words make recommendations for the tuneup required for the car give me the optimal mpg, I expect the car to me 30 mpg or more, thanks for everything, Greetings for this great forum...

 

 

I've also noticed that the car shakes a little when I'm waiting for the green light at the semaphore...

 

The secondary O2 sensor plays no role in determining the fuel trim, so it's no surprise that replacing it did not improve gas mileage. Check whether any new CEL codes have popped up since replacing the sensor. Click on the CEL sticky.

Next do an ignition system tune up. This involves replacing the spark plugs, wires, cap, and rotor, and adjusting the ignition timing to spec. Install ONLY the basic NGK spark plugs recommended in your owner's manual. There's a diagram in the FAQs sticky that describes how to adjust the ignition timing.

What trim Civic (cx, lx, ex, hx)?

 

Thank you "Ronja @ HT" for your answer, is a Honda Civic LX, I change spark plugs only of dual electrode but no "NGK", the car does not bring any code "CEL", since remplazed the sensor, I will make the ignition recommend tune up then, thanks for everything

 

Only a question, what's "CAP"?... Regards

 

distributor cap

 

ok