Marcos

I have a 2000 Honda Civic Si. I've been driving it a lot as of late and I have noticed the mpg are terrible. I'm getting somewhere around ~20mpg. I've done some searching and found that it could be a bad O2 sensor. Would it be the primary O2 sensor then? Where is it located at and is there anything special needed to get it out? I was thinking about taking the O2 sensor to Autozone and have them test it. Other things I've heard are spark plugs. How often should those be changed in my car? Any other suggestions? Thanks..

skribblah

you have a 2000 si and dont know much, so this is what I would do if it was my 1.6L getting 20MPG.

keep myself from flooring the bitch at every stop light

change the spark plugs

check/clean air filter

toss in some injector cleaner

change oil

make sure TB isnt gummed up

and since your car is a 2000 i really doubt the O2 sensor is bad, but what the O2 sensor does is, its located in the exhaust pipe and it detects how lean/rich your engine is running, reports this back to the ECU and the ECU takes that measurement and adjusts the air/fuel ratio accordingly. thus if your O2 sensor was bad, then it would give false readings, EARGO the ecu would be dumping more fuel in the engine when it isnt needed. this is also called "running rich"

sorry for sounden like an **** hole! im not one!

Marcos

Haha, well to let you know, I did know everything you mentioned right now, I just didn't know where it was located exactly on my car so I asked...

I don't floor my car at all when I drive. I don't go beyond 3,500 rpms. My car does have 50,000 miles though. I bought it used with around 45,000 miles about 10 months ago. So far I thought of all these possible things: new spark plugs, new spark plug wires, fuel filter, distributor cap, and clean/new air filter.

I just don't want to do all of those things and it not help (can't hurt either though), but I don't have all the money in the world right now. I've searched and people have done all of these things with it still not fixing the problem. Another thing I wanted to note was that my car feels like it bogs sometimes (could just be my driving, but it seems to have gotten worse). Plus, starting my car seems real weak sometimes (usually every couple of days it will happen). It will just barely turn on. The car runs great other than that.

Edit: By the way I was told it was located on the header right before the cat?

EVIL Hx Coupe

I have an HX, which is supposed to be the gas Economy model, and I noticed that lately I was getting shitty gas millage...

I used to get 40mpg and I was getting about 27 by the time I noticed.... Anyways, I changed my spark plugs, wires, cap, rotor, and used an injector cleaner and I'm back to getting 40mpg again...

Try changing all that out and see if it helps... IMO I thing you should do that to every car right after you buy it.