themcneal

iTrader: (1)

Hello,

Just wondering what the symptoms are of a bad O2 sensor. I am curious if the car running rich is one of the symptoms (since my car is running rich currently).

Can anyone provide some info?

BTW, if it matters, I have dp, catback, high flow cat and stock computer.

Thanks,

Mike

clayne

Oscillation in throttle under 3500 rpm when cold (no, not the 3krpm hesitation either).

patfat

I belive the check engine light will also come on. How many miles are on the car?

themcneal

iTrader: (1)

The car has about 120K on it now, with the last 02 sensor replaced around 75K or so, if I remember correctly.

Toadman

Hey Clayne, mine rpm-oscillates on cold starting but stops after 3-4 revs as temps climb. It's the AWS coming off line I thought.

moehler

iTrader: (12)

http://www.oxygensensors.com/

If your worried about it, just get a new one... it's only $45.

dgeesaman

iTrader: (7)

I just replaced mine yesterday.

Car would have jerking hesistation from 2k-3k when it was in warm-up mode. Now gone, based on my quick test drive.

Replaced with Bosch Universal sensor for $17 from Autozone. Went in only with a crows-foot wrench since the Bosch Uni is bigger on the backside and the turbos blocked getting the O2 sensor socket on. I have a Pettit DP tho - other DPs and precat should be easier.

Dave

clayne

Toad, it's definitely the O2. The severity of it determines how long it takes to actually get accurate readings.

It's not AWS. I have no AWS w/ a Power FC. When driving the car after starting it up (and even letting it warm up to 180) the car would hestitate and release while at steady state throttle right up until 3500 rpm where it magically stop doing this oscillating throttle.

PFC shows O2 voltages flying back and forth during this time, also INJD varying by about 2-3% as well (what's causing the hestitation as throttle position is constant).

Upon disabling the use of the O2 sensor, within the PFC, I get no hestiation or throttle oscillation under 3500 rpm. This would say to me that my O2 sensor was the culprit.

clayne

I should also add to this:

After driving the car and generating reasonable amounts of boost and EGTs my O2 sensor then works reliably again. This follows the theory that when the sensor itself is going bad it will provide wrong readings when cold, but when the sensor body is warm you will receive accurate enough readings.

My advice: replace the sensor if you still use it.

InsaneGideon

Strange, most cars' ECUs completely ignore the O2 during warmup (open loop) for precisely this reason.

I haven't tinkered with the O2 on my stock FD, yet. Do we have heated sensors (which would explain why the ECU goes into closed-loop so early)?

clayne

No heated sensor. Your best bet is to remove the O2 sensor and put a wide-band in there with a Power FC.

poss

iTrader: (5)

To my knowledge, the stock ecu does operate this way.

InsaneGideon

I wasn't having this problem! My FD is stock, lo-mi, and pretty well functional.

I'm going back to live in my bubble now, until I start having boost problems like everyone else.

Though I was contemplating the AEM WB with the cool new meter.

theone81

Where is the o2 Censor Located???

Androidmj

its the thing screwed into the dp or precat with a single wire coming out of it.