Okay, here is the problem. Lately when I start my car when its cold it will idle really high, about 1300-1600 RPM, until it warmed up.

And ever since this started (or a little after) Ive been getting REALLY shitty gas milage. I think Ive only been able to get about 180-190 out of a full tank, and a light foot. I used to be able to get 230 easy, and that is with a couple trips to redline a day.

Ive come to the conclusion that its either my timing is off or a bad o2 sensor(s). There is no check engine light, which is weird if it is the o2 sensor. Anyone have any ideas as to what it could be? Any help and/or flaming is welcome and appreciated some more than others. Thanks in advance.

 

o2 sensor should throw a code, mine did....im baffled

 

there is another thread on here actually about a similar situation.. had a bad primary O2 but no code..

 

No, the O2 sensor won't throw a code until it is beyond fucked up - at least, that has been my experience and I've changed mine 3 times now. I change my O2 sensor every 70k (maybe a little earlier) in my 99 hatch. When I accrue that many miles on the O2 sensor, my gas mileage and acceleration start to take a hit. I would get a clean 38-40 with a new O2 - at around 70k I would get anywhere from 32-36 with an occasional 38 and a definite decline in acceleration.

My idle wouldn't really be any worse off - you could tell a difference after you replaced the O2 sensor with a new unit but my idle never worried me when the O2 had some miles on it.

On the other hand, I have a completely bone stock Y7 in my hatch - and that ******* motor burns lean as hell. Everytime I've pulled my plugs and O2 sensor, they have always been white, with a hint of tan (210k on the clock). I mention this, because rich mixtures, burning coolant or oil, will cause a faster deterioration of the O2 than what stock conditions would do to it.

Timing is easy - grab your timing light and check it - no need to guess if it could be the problem.

 

Sorry to jack the thread, but I have the same problem.

What is a decent O2 sensor to get? One that is near compatible with OEM standards? These are a bit pricey I hear. Thank you.

 

If after searching, you don't see a trend between aftermarket O2's and how well they DON'T work with Hondas, then go ahead and purchase one of your choice.

Some people have good luck - it would seem the majority do not. O2's that require you to do any soldering or crimping in order to adapt them to your stock harness should not be considered, IMO.

I'd stick with OEM for O2 sensors.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dimi &raquo;</TD></TR><TR><TD CLASS="quote">Sorry to jack the thread, but I have the same problem.

What is a decent O2 sensor to get? One that is near compatible with OEM standards? These are a bit pricey I hear. Thank you.</TD></TR></TABLE>
give your car a full tune up and valves adjustment. use ntk or denso o2 sensor.

 

A shot in the dark here, but what year is your car?

I've not known an o2 sensor to mess up ones' cold-start idle, but it can affect gas mileage.

If your car has a fast idle valve on the bottom of your throttle body then I'd start there for the idle problem. It has a plastic disc in it that can come unscrewed, which causes a higher than normal cold start idle and eventually it will cause the idle to fluctuate after the car is warmed up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 &raquo;</TD></TR><TR><TD CLASS="quote">A shot in the dark here, but what year is your car?

I've not known an o2 sensor to mess up ones' cold-start idle, but it can affect gas mileage.</TD></TR></TABLE>

Its a 1996 Ex coupe. 133,xxx miles on it. Ive heard good things about Denso o2 sensors. Anyone know a little bit more about them? Are they just a direct install or do they have to be modified for proper installation?

This is really pissing me off, because not only am I short on money, but the fact that I have to fill up even more isnt helping at all.

And I want to know how to check and see which of the o2 sensors is bad. Because I know my car has 2.

Thanks for all the help so far guys. I really appreciate it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHC4life &raquo;</TD></TR><TR><TD CLASS="quote">

Its a 1996 Ex coupe. 133,xxx miles on it. Ive heard good things about Denso o2 sensors. Anyone know a little bit more about them? Are they just a direct install or do they have to be modified for proper installation? </TD></TR></TABLE>

I'm not sure because all we sell are OE Honda units. I'd try them if they are a direct plug in though - Denso is good stuff usually.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">]This is really pissing me off, because not only am I short on money, but the fact that I have to fill up even more isnt helping at all. </TD></TR></TABLE>

Yeah it sucks, and worst of all you cannot be 100% certain it's the o2 sensor(s) without having them checked with some pretty expensive scanning equipment that reads o2 signals.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">And I want to know how to check and see which of the o2 sensors is bad. Because I know my car has 2.</TD></TR></TABLE>

See my previous statement. You'll need to find a shop that has the capability of reading the o2 sensors' outputs/signals and see if they're within specs according to Honda. It is possible to have a bad o2 and it still not throw a CEL code for it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for all the help so far guys. I really appreciate it. </TD></TR></TABLE>

That's what H-T is about!

BTW:

I think your car might not even have a fast idle valve, but an electronic idle air control valve that does most if not all of the cold start idle functions on that car. older OBD1 cars use a mechanical fast idle valve in conjunction with the IACV to control the cold and warm idle speeds. the weird thing is your IACV would typically be throwing a CEL if it was bad, but just like the oxygen sensor it can be tested with the right scanning toll as well.

 

I am running a denso first-time-fit sensor
Its quality
No issues what so ever.

I bought it for under $65 shipped from an ebay store
This seller
http://cgi.ebay.com/ebaymotors...46097

 

Cool, thank you very much. Anyone one else.

And B18C5-EH2 thank you very much for all of your input. Its been very helpful.

I have another question. Which would be cheaper, replacing the o2 sensor, or having them checked by the computers to see if they are working properly?

I would rather change the sensors if it were cheaper, not just to save money but that way I know how many miles will be on them.

Edit: Also, are the o2 sensors in my car 5 wires or what? Ive never really looked at them and I'm at school right now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHC4life &raquo;</TD></TR><TR><TD CLASS="quote"> Which would be cheaper, replacing the o2 sensor, or having them checked by the computers to see if they are working properly? </TD></TR></TABLE>

When my shop hooks up a scanner for CEL codes I don't charge the customer, but to check signals from various sensors and whatnot it'd probably be anywhere from $50.00-$71.00 or so. That's cheaper than an o2 sensor, but it would also be that $50-$71.00 plus the sensor or sensors themselves.

If you're going to get it hooked up I'd also ask them if they can test the electronic idle air control valve too to see if it's functioning properly. A shop with a good scanner and All Data should be able to check that, but I'm not sure what shops around you have such equipment.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I would rather change the sensors if it were cheaper, not just to save money but that way I know how many miles will be on them. </TD></TR></TABLE>

I understand that point, but you also don't want to waste the money spent on an o2 sensor or sensors if you don't need them right now.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Edit: Also, are the o2 sensors in my car 5 wires or what? Ive never really looked at them and I'm at school right now. </TD></TR></TABLE>

Nope. Both of yours are 4 wires. The Civic HX and VX used the 5-wire hellfied expensive sensors. Yours are located:

Primary - in the "A-pipe" portion of your exhaust before the catalytic convertor.

Secondary - in the back of the cat convertor

 

Awesome, Thanks again. So can anyone else give me more information? Mainly about the denso o2 sensor.

Bad gas milage sucks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ej0513 &raquo;</TD></TR><TR><TD CLASS="quote">there is another thread on here actually about a similar situation.. had a bad primary O2 but no code..</TD></TR></TABLE>

yeah not to jack your thread but that was probably my post.

we hooked up an obd2 scan tool and my primary wasnt geting any readings secondary seemed fine. and my engine is misfiring i dont see anything else wrong with teh car besides this.

is it normal for an o2 to be bad and throw no codes and cause misfire?

 

I replaced my O2 sensor w/ a Bosch unit & I have had no problems w/ it over the last year.

 

Have you all noticed an increase in gas mileage and overall better response from your motor (the ones that replaced with new O2 sensors)?

 

i thought i read somewhere that honda oem o2's were bosch. maybe im wrong.

 

I definately noticed a significant increase in MPG after the new O2 was in. I noticed another big improvement in MPG when I swapped a D15B VTEC into my car instead of the old D15B7. I didn't really pay enough attention to the before & after results of the sensor, but it was enough to notice. And I am getting about 6 MPG better w/ the VTEC motor VS. my old worn out motor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mugenEG2 &raquo;</TD></TR><TR><TD CLASS="quote">i thought i read somewhere that honda oem o2's were bosch. maybe im wrong.</TD></TR></TABLE>

I seriously doubt that the OE Honda sensors are Bosch. They look absolutely nothing alike, and Bosch is typically for German cars.

The OE Honda sensors look very similiar to the NTK and Denso units.

 

So a Bosch "O.E.-Type" unit wouldn't be good to run? $60 really beats the hell out of $175 for OEM Honda.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dimi &raquo;</TD></TR><TR><TD CLASS="quote">So a Bosch "O.E.-Type" unit wouldn't be good to run? $60 really beats the hell out of $175 for OEM Honda.</TD></TR></TABLE>

It's worked out fine for me, but others say that they don't last long. I've been running one for about 1 year and it's still working perfectly.

 

Thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pdiggitydogg &raquo;</TD></TR><TR><TD CLASS="quote">I am running a denso first-time-fit sensor
Its quality
No issues what so ever.

I bought it for under $65 shipped from an ebay store
This seller
http://cgi.ebay.com/ebaymotors...46097</TD></TR></TABLE>

Denso for $65 That will be the one I purchase when I get the money.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DJ_SaNdOz &raquo;</TD></TR><TR><TD CLASS="quote">

It's worked out fine for me, but others say that they don't last long. I've been running one for about 1 year and it's still working perfectly.</TD></TR></TABLE>

But how many miles are on it?