Signs of a dead WB O2?

[Nashty]

Last weekend at the Midwest challenge, the car was popping really bad only at upper RPM under load. Coil pack checked good, new plugs and recent wires. Plenty of fuel pressure and volume. Car just about cuts out. It seems like a lean pop to me (intake).

Plugs are quite white, tried 103 & 104's - no help. Approximately 10% of fuel is always being pulled out (just like it did when it was first tuned). O2 is around 10-9.5 : 1 and NO black smoke. Starting to see pieces of head gasket in recovery tank and pushing out some coolant. NO KNOCK at all. Problem is, the car has always been a smoker (oil). Can the O2 go out after about 75-100 miles of this smoke? Most of the mileage is track type (to from lanes, passes etc.)

Is there anyway to check the sensor? Anywhere to send it to check it? Are these things really ~$350?

 

[njrob6]

I got the same problem except my engine never burnt oil, i think I blew a head gasket. Im gonna do a leakdown test today and see what comes up. What I want to know is if burning oil through your exhaust ruins the O2?

Rob

 

[Lance]

If oil is being introduced in the exhaust and subsequently deposited on the O2 sensor, you can expect an abnormally rich (false) reading followed by complete failure of the sensor. The sensors are not designed to work with oil.

You can check the condition of the sensor by observing the "UEGOS" sensor in the main dashboard. With the engine operating, it should be ~.45V. If it varies from this significantly, you may have a problem. Contact your dealer or FAST.

It would be extrememly unusual for a failed sensor to read excessively rich as the ECU monitors the condition of the sensor and will suspend closed loop operation if it's out of spec. The majority of any failures have been to read lean.

 

[Craig Smith]

One other thing...

In addition to Lance's comments regarding oil and O2 sensors, pushing coolant across an O2 sensor is also VERY harmful to the sensor. Not just this sensor either... ANY O2 sensor hates coolant. If your sensor has been subjected to anything more than a little tiny bit of coolant, I'm sad to say that I would be prepared to replace it. You may be OK, but I would keep an eye on it if I was in that situation.

Craig

 

[njrob6]

Could an O2 sensor still be bad even though the UEGOS still reads .45 V

Rob

 

[Nashty]

What a pisser. I don't think it passed any coolant but with my luck, it probably did.

You're saying that the UEGOS value should be ~.45 when at operating conditions (warm, in closed loop) or when I fire it up cold. I'm not lazy, just asking so when I look at it tonight (I'm at work now) I'll know.

Since the thing was running pretty hard (but still pulling fuel out), would you suggest I run it in open loop for a while on the street to just get the darn thing to stop smoking? I don't think it's the turbine seal, probably piston rings. If I do that, won't it be constantly 10% rich unless I pull the fuel out? Should I take it out and make some around town observations to see how much fuel to take out of the cells? Is it safe to make a 10% global reduction?

Is it best to lower the VE numbers or should I be raising the A/F?

How much is the WB O2? Can I get it from any FAST dealer? Can it be sent somewhere to verify it's demise? I hate to spend that kind of dough on something I "think" is bad. I don't need a back up that bad.

 

[Lance]

The UEGOS reading should stabilize to .45V within a minute or so. It appears to me that the older the sensor, the longer it takes to reach this point.

I have had reports from users that sensors that seemed to be on the outs were revived by normal use of unleaded fuel.

I don't have any advice for fooling the system but if you want to compensate for a perceived error in AF, you probably should do it in the AF table. Otherwise the calibration will get skewed.

Since we don't sell direct, I really am not sure of the replacement cost. Also, there have been recent price increases from the manufacturer that may have an effect on our price. Check with a dealer. (part #30-7000)