Im planning on relplacing my o2 sensor sometime this week and wanted to know how hard they are to replace for a novice mechanic? Are there any write-ups or how to's? Also what are some of the symptoms of a faulty o2 sensor? My care is experiencing a kind of rough idle when in drive and reverse at low rpm's (cuts off sometimes when put in reverse when it hasnt been drivin in 12 hours). Its not too bad but definately noticable, exhaust also smells kinda rich, but check engine light is not on.

thanks in advance for any and all comments.

 

Its simple, if you have to break it loose that would be the hardest part, just unscrew it unplug it, then screw in the new one and plug it in.

 

O2 sensors will typically trip a check engine light of there is an issue with the exhaust. if the sensor is bad - not operating correctly - it may not be reacting correctly to the oxygen levels in the exhaust.

none of the symptoms you describe seem O2 sensor related however.

sounds more like a miss - but that's just a remote diag

 

yea thats what i always thought was that it would trip the light, and yea it feels kinda like a miss but its not always noticable though just mainly at a redlight, mcdonald's, or like when im pulling out of my driveway, and its still not like violent or nething it drops to about 4-500 rpms for about 4 or 5 seconds and then stops when the fans kick on(i think) and raise it to over a thousand. when it misses like with an injector wont it be alot more violent? i also had a tune up done about 2 months ago and they replaced the radiator, distributor cap (what i was told was making it skip before),wires, and plugs, and it worked fine for a day or 2 then started doing this again. any other sensors it could be, or tests i could run myself? i appreciate the help!

 

If your fans are kicking on I might question the coolant temp sensor.

 

fans kicking on should not bump up your rpm's that much as they are electric and not belt driven. do you mean your cooling fans or perhaps something related to your climate control?

it really doesn't matter in any case.

misses present themselves at different rpm ranges. it all depends if you have an inline or a v-block and then if it's only one cylinder or more. even if you have mulltiple misses, the harmonics of the engine could be such that they "balance" each other effectively and result in lesser-than-expected vibration.

i would start testing the resistance across the injectors. i'm sure there's a right up on the board somewhere. 5 of my injectors test bad and there's a small window of operation where you can really notice. actually it feels like it's about to stall even though the rpms are within range. i figure i wait for my holiday bonus before i plunk down another $600+ for all the injectors

 

a bad o2 will not neccessarily trip the CEL.
if it has failed completely then it WILL trip the light, but a slow sensor won't trip it.

 

Just say when

 

Also, there's an easy test of the O2 sensor using the lights on the ECU. I don't know which car you have, but on my '92 SE, you turn the screw on the ECU (on hump, under dash) and the LED on the unit and the Check engine light blink. After the engine is warmed the blinks should be X blinks per second (don't remember exactly, but this should be written up on the Autozone site or in the stickys). This should tell you if the O2 needs changing.

 

When I had my y-pipe installed the wire on the o2 sensor broke and I had to by a new one. It did not trip the check engine light. Was something wrong or is this normal?

 

normal .

 

it was prolly the a/c compressor and but i thought it was the fans bc u can hear it come on but i knew it was one or the other! haha,neways it will kinda go up and down between 500 and 600 and when the compressor(i guess it is?) and quits at about 800 or 900. oo and also its a 93 gxe, could the timing cause this? cuz its been over 70k miles since it was changed. also does anybody have a write up or can give me steps to checking the resistance on the injectors?

 

The bouncy idle sounds like a bad coolant sensor. Replace the 2 wire one, its like $12, and clean the connector and use connector grease. Then check back with us. And change that timing belt, they are suppose to be changed every 50-60K.

~Alex

 

where is the sensor and is it somewhere i could change it myself with simple tools? oh im going to change it, just got a job with ups and have to save up some money haha, but im goin to buy some new spark plugs this weekend first just to make sure its nuthing simple like that, i heard the ngk iridiums were the best ones to get, that true?

 

Something pretty simple to check if your o2 is going shady on you... if the gas smells Richer then usual its a possibility its going on you.
On that note, your MAF could be going bad as others said above.

I had a problem where my max failed emmission tests and looking at the emission results the carbon levels were high, i noticed also the gas was smelling rich. I did end up finding that the o2 sensor was faulty. But the MAF sensor was still going good.

I had changed:
-Spark Plugz
-Plug Wires
-Distributor Cap / Rotor
-PCV Valve
-hi flow intake Air Filter
-Fuel Filter
-Injectors were fine so there was no need to change them.
and lastly the thing alot of people dont check, the leads on their distro cap or / coil. and check for faulty coils.
Check your EGR valve too.

changing or checking these things will narrow it down to the electrical and more technical side as too why it could be running terrible such as:
-Grounding Wires
-O2 Sensor
-MAF Sensor
-Throttle Position Sensor
-Coolant sensor
-ECU (try resetting)
-Aftermarket speed chips ( if used) dont have these gimmic things haha!

After checking and replacing what needed to be changed, It narrowed down to those technical areas... the o2 was the culprit. And the gas stopped burning rich.

I hope that helps if you still have those issues.

 

oh yeah NGK's are good to use, Im using the splitfires right now tho, those arent bad either hehehehee.
by the way the o2 sensor is located below where the exaust pipe is, close to where it joins to the y-pipe if i remember correctly.

 

Where is the coolant sensor located, also how do you re-set the ECU.

 

Just disconnect the negative cable on the battery for a while to clear the ecu..

 

good one greenmax94, two birds with one stone LOL!!

By the way regarding the coolant sensor, its not a big problem when it comes to the combustion department, but if the coolant sensor is faulty, it screws up the voltage patterns assigned from the ECU. It can then tell the ECU to do other strange things like turning on your rad fans for no reason. Anyways, In result, the ignition coil gets an inconsistant flow of current causing the sparks assigned to the plugs to not be at its probable full potential. On top of that other electronic sensors, can get thrown off too with the durastic ON / OFF faulty of the coolant sensor.
Which goes back to your car running like crap again.

 

how do u tell if ur sensors bad?

 

if you can't remember replacing it, then chances are it is bad

 

couldn't a bad exhaust leak cause a o2 sensor code to

 

Not likely,all the o2 does is "smell" for raw gas so to speak,then it relays this info to the ecu,then the ecu will adjust the air/fuel mixture accordingly..an exhaust leak is irrelevant to it's purpose..

 

actually it measure the amount of oxygen in the exhaust.
an exhaust leak will cause it to read wrong, but won't hurt it in the short term

 

If you're referring to switching onto R (everse) or D(rive) from P(park) and it shuts off it could be your timing cuz I just fixed my timing today..it was WAY off and now idle is SOLID steady which it has never been like since I got the car. After adjusting timing it doesnt stall when switching to D or R

 

http://www.autozone.com/servlet/UiBr...3d801f4eba.jsp
THis link explains how to test the coolant sensor.

 

Well,i knew it "smelt" something..

 

it smelt yo gas

 

how can i tell if my 02 is bad im selling the car but it needs to pass inspection smells like **** after a tuneup and engine flush

 

I've never heard of an exhaust smelling like excrement, it normally smells like rotten eggs aka sulfur, or sweet.
Believe me I know what excrement smells like, I have 3 young kids and 1 in diapers still. never had exhaust smell like it.

 

another kind of **** and not the good kind i got a 94 firebird with no cats emissions it smells good... rotten eggs or sulfur or just raw exhaust would be close, muffler cat or O2?

 

now that was funny.....the hole will let in fresh air and will do 2 things 1 is make an exhaust temp change and also lean out the exhuast fumes giving the 02 a false signal to REPORT to the computer
I have seen in my exper with 02 sensor is that about 1/3 can be cleaned and reinstalled to work fine..