Oxygen Sensors

[tbone]

I was talking to Zack at my get together a while back about my car's issue with not starting a couple times last winter, needing a couple revs on cold starts it to get a little stumble out of it, and the fact that very occasionally it will stall if I don't rev it a couple times, also only on cold starts. He seemed to think that the oxygen sensors probably are "lazy" and need to be replaced, even though no codes are being sent. Sounds reasonable to me.

Anyone have a similar experience? Advice? I don't want to spend the money if I don't have to. I already replaced the IAC and it didn't help.

[guspech750]

My advice is. Let's have another party at someones house or CSVT picknick Sunday and we will discus your possible O2 sensor with beer and food!!! :)

Wish I had an answere for ya bud.


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[mcgyver59]

Get a datalogger and monitor o2 voltage. It should dip down as low as .08ish and up to .99 volts. If its far from these lows and highs they are lazy.

[tbone]

Sounds like a plan.

Hey, I like your O2 sensors!

[mcgyver59]

It could also just need more fuel on startup in the tune.

[tbone]

It could also just need more fuel on startup in the tune.

Could be. But it started long after I got the tune.

[tbone]

Rock Auto lists upstream and downstream sensors. Aren't there only 2 sensors upstream of the cats? I know there aren't any after the second set, which I removed.

[mcgyver59]

You need the green ones, rock auto has a pic.

[TFB]

The o2 sensors are totally inoperative on a cold start... I'd be more inclined to think the temp sensor or tune was the issue...

[justbob]

You really need to data log.

[tbone]

You really need to data log.

Does the xcal2 do that?

[tbone]

The o2 sensors are totally inoperative on a cold start... I'd be more inclined to think the temp sensor or tune was the issue...


Interesting. I'll look into that. Thanks.

[tbone]

The o2 sensors are totally inoperative on a cold start... I'd be more inclined to think the temp sensor or tune was the issue...


Are you talking about the emissions air temp sensor as shown here?

http://www.rockauto.com/catalog/moreinfo.php?pk=39905

[tbone]

Here's a good article I just found which describes my issue perfectly.

Is the mass air flow sensor and the air temp sensor combined in our cars? My MAF sensor is spotless.

http://www.crxusa.com/info/driveability-diagnostics-emissions/Engine-Air-Temperature-Sensors.htm

[RF Overlord]

Rock Auto lists upstream and downstream sensors. Aren't there only 2 sensors upstream of the cats? I know there aren't any after the second set, which I removed.Stock there are 4 sensors. The two upstream of the cats do the actual A/F monitoring, while the 2 downstream are "catalyst efficiency" monitors.


The o2 sensors are totally inoperative on a cold start...^^^what he said^^^

The motor is in open loop and ignores the O2 sensors until they're up to temperature, at which time it goes into closed loop and uses the input from the sensors to control A/F in real time.

[tbone]

Stock there are 4 sensors. The two upstream of the cats do the actual A/F monitoring, while the 2 downstream are "catalyst efficiency" monitors.

Thanks for the info.

[zman]

Data log
Data log
Data log

[tbone]

I changed out the sensors today. What a pain. Very little clearance to get a wrench in there. The driver's side was actually easier to remove from above.

The cold start issues are gone now. Starts right up, settles into a normal idle right away, no stumbling/hesitation/stalling at all.