to start off I had my car for quite a while, did a first oil change about a week ago at around 3700 miles. Lately, I realized that I smell gas smell coming out of exhaust, especially when it is cold, didn't really notice it before. also i get about 18-19 mpg with nearly 100% city driving in my commute to school which is about 13 miles. Do you think my car is running rich? any advice?

p.s. engine check light was never on.

 

yes, if theres gas coming out of your exhaust, go and get your timing belt checked by a mechanic

 

You should be throwing a code if you're running rich. Take it to the dealer since you're under warrantee.

 

O2 sensor failure won't throw an O2 code.

 

Sorry to bring up an old thread, but I did a lot of searching.


Sometimes it feels like my TSX is sluggish, like the v-tec isn't engaging. It happens mostly on the freeway after the car has been on for an extended period of time. I'll downshift (6mt) to maybe 3-4th gear and go WOT to pass a slow vehicle in traffic or to merge onto the freeway and the car will feel slower then normal. It will feel much like if it's extremely hot outside or you're driving at a really high altitude, but the majority of the time the car will feel fine. It doesn't make any funky noises either, it will just occasionally stumble a bit when I turn the engine off.

I'm thinking I have an 02 Sensor out, but I don't have a CEL or any other light on. I have some soot on the rear bumper and dirty exhaust tips, but my gas mileage is normal for the most part and I only burn maybe a quart of oil every 3000 miles. I've also never cleaned all the soot off, so it could just be from a previous repair (the car is used).

I'm not sure if there's really a problem at all, maybe I'm just used to the car and it doesn't feel fast to me anymore. I always seem to get really paranoid about something going wrong with my car.



The exhaust looks very similar to this

 

The O2 sensors are tricky little buggers. The idea is that response voltage represents a linear result of changes in the O2 concentration (or maybe logrithmic, I'm not exactly sure, the main point being that it's consistent). The problem is that the sensor can be bad but not bad enough that the ECU recognizes it's broken. For instance maybe it's reading 20% lower than the actual value when the sensor reaches a certain temperature. The ECU would not see that value as being out of the ordinary and would adjust the AFR accordingly to bring the reading back to where it wants it to be. Now the sensor is reading correctly but you're actually running 20% too rich.

You'd need some sort of calibrated testing equipment to know for sure. Do shops have that sort of thing? I don't even know.

 

I took a look at the sensor a few minutes ago, it looks like the wire sheath is pulled back and the wires are exposed. I don't know if that could possibly have damaged the wiring or a connection somehow.

 

^^^ It comes like that.

 

Yeah, that's normal.

If you're really concerned about running rich, you can try to get scantool that will read the O2 sensor reading from the ECU. Actually since you're under warranty, see if the dealer will take care of that.

 

If the O2 sensor isn't working right, the scan tool would be useless.

 

Is there a longer warranty covering this type of thing? I'm the second owner (04) and the car has 74,000 miles on it.

 

Hmm. Sorry for the threadjack...

I never really noticed my car being sluggish until I drove a loaner TSX. I have an '04 and the loaner was an '08, so I know the '08 has 5 or so more horsepower than the '04s, but in my car I can't feel VTEC kick in. I could definitely feel it in the loaner. Would 5 horsepower really make that much of a difference? Also, I don't get the gas mileage I used to get when I bought the car. I used to get 28 or so MPG with mixed driving, and now I get 26 or so MPG with mixed driving.

If it's true that a malfunctioning O2 sensor won't trigger a CEL, how do you get the dealer to replace it? Is there a test they can perform? How much is an O2 sensor for the TSX?

 

If you get a OEM one online it'll be around $200, but at the dealer they want like $350 . I hope they have a warranty for it, I don't really have an extra $300 to spend .

 

Actually, I lied. I just went out and looked at the trip computer in the navi and it says 28.4 MPG so far (only burned 1/4 of a tank of gas, though).

I sound stupid and feel like a noob asking, but is the 6k VTEC limit supposed to be noticeable in the '04 as it is in the later version of the TSX? Does 5 HP really make that much of a difference? To me, the car feels dead-ish when it's revving that high, but I don't have another '04 to compare it to. I've only driven my '04 and an '08.

 

The throttle body got bigger in the '06 so that's going to make a noticeable difference when the engine is breathing it's hardest. It's a somewhat common mod to swap the old TB for the new one.

Back on topic, the exhaust is specifically excluded from the warranty. You're on your own with the O2 sensor.

 

This is NOT entirely true. When my air/fuel ratio sensor failed, it definitely threw a CEL. I've read members having O2 sensor failures without CELs.
I recall a member trying to get the air/fuel ratio sensor (primary O2) replaced under warranty, but the dealer denied him stating the sensor wasn't part of the 7yr or 8yr (can't remember which one) emissions warranty.

 

Hmm. I think I'll add that to my list of possible mods. Only 10k miles until the warranty expires. *twiddles thumbs*

Isn't there a special emissions warranty for Californians (due to our strict smog rules)? Does that specifically exclude O2 sensors?

 

I am not familiar with your weird left coast rules. I think they consider the O2 sensors a wear item though.

 

Actually, it wouldn't be useless at all. Your O2 sensor will help the engine maitain an ideal air/fuel ratio of 14.7 when the car is at idle or cruising. If the O2 sensor is bad, the engine will struggle to maintain that 14.7 and you will get very eractic readings. Usually the car will go into limp mode and maintain a richer mixture of closer to 14.0. In addition, the ECU will never go into open loop mode.

If you have the scantool hooked up and see that the air fuel ratio is closer to 14.0 instead of 14.7. And that the car will never go into open loop mode ( it never really changes from 14.0) then that is a tell tale sign that the O2 sensor is failing. Another sign of a bad O2 sensor is erractic idle at a stoplight. RPMs will flactuate up and down, especially with the AC on.

This comes from my own experiences of diagnosing my own bad O2 sensor. When that happenned to me, I had the Brockway R920 reading my O2 sensor reading from the ECU and a PLX wideband O2 sensor reading directly from my header, so I have a lot of experience with what the O2 sensor should be doing.

I'm not sure that this is the OP problem, he should be throwing a CEL if the O2 sensor is bad, but just trying give info that is hopefully helpful.

 

I think it's up to the dealer whether or not they want to replace the O2 sensor. I've heard of some members getting them replaced when they were still under 50K. I got very lucky and had mine replaced as a goodwill when I had 58K. They even saw my Supercharger setup, but still took care of me.