kevo156

I have a MY2000 with 121,XXX miles and my gas mileage hasn't been very good. I have changed the spark plugs, air filter, fluids, new tires, ect. The car seems to be running rich. Just wondering before I buy a $200 O2 sensor if it could be anything else first. There is no CEL and the car doesn't seem to have any other problems. I have a pic of one of the spark plugs but I'm not sure how to post it. Thanks for your help.

hrpfg2

have you checked for leaks?

what kind of gas mileage are you getting?

kevo156

Around 19 mpg mostly highway and not driving aggressively. The exhaust tips turn black a day or 2 after I clean them. Also my new spark plugs look black. I just did a compression test and it was 210 across the board.

kevo156

My mechanically inclined friend who is very familiar with s2000s thinks its most likely the o2 sensor. I wish there was a way to test it first before I buy a new one.

kevo156

[quote name='hrpfg2' timestamp='1334854907' post='21623734']
have you checked for leaks?

The car isn't leaking anything. My garage floor is clean.

hrpfg2

I was referring to fuel leak.
but if you are seeing black plugs and black exhaust tip then fuel leak isn't your problem.

bad 02 will make your car run rich.

any mod on the car?

kevo156

No it's not leaking fuel for sure as I would smell it. No mods bone stock. I feel like it's likely the o2 sensor but why isn't there a CEL? And is there any way to be sure?

hrpfg2

They won't always throw a CEL. Sometimes you can get a bad O2 sensor where it doesn't respond quickly thereby sending updated emissions data to the engine computer. Try reading the codes, sometimes a code will be stored but not turn on the CEL because it has to see the fault for x amount of drive cycles. If no code is stored, and you suspect an O2 sensor, you need to look at the O2 sensor values on a good scanner.


another thing you can look for is cracked or disconnected vacuum hoses

kevo156

I'll check the OBD11 code. If nothing is there, what kind of scanner do you mean?

hrpfg2

OBD2 scanner with live data.