What are symptoms of oxygen sensor failure? My trouble light comes on intermittently on the road, and engine then runs rich with a power loss & no acceleration. Goes away on restart.

Also weird: Trouble light comes on intermittently at startup, but if I turn off the ignition and wait 20 seconds to restart, trouble light goes off & all is okay. VATS?

Haven't checked codes, yet.

 

O2 sensor is the only sensor on the car that actually generates voltage.

Connect a voltmeter to the sensor, and observe voltage delivery once the sensor is at operating temperature.


http://www.autotap.com/techlibrary/u...en_sensors.asp

 

Thank you. Very helpful explanation on this site.

 

I would try to pull the codes. The reset of the ecm and all is well sounds like it could be a faulty ecm. But start with the stored codes first then trouble shoot from there.
The o2 swings from .450mv up and down. Stuck at .450 it’s inactive due to being bad or not upto 5-600f to become active.

 

No codes. ECM replaced recently, no change in bad behavior.

 

What modifications are present on this vehicle?

 

No Cat, so no after O2 sensor; replacement engine bored out to 354 cubes, TPI, with rollers & performance harness; Flowmaster muffler; 3-core radiator & elec. fans; MAF is from a Corvette. Cluster replaced & board added for tach accuracy. The engine is "Wonder" brand & has bore holes through the water jacket, so there could be a leak, though I plugged one (of two) with a stud. Sometimes, dipstick pops up. (blow through?) Cruise control works, but won't hold constant speed & causes car to throb. (ECM getting bad 02 sensor data or vacuum leak under the dash?) Whew!

 

Have you got around to pulling the trouble codes ?

 

Running a MAF that isn’t matched to the ECU could cause interesting issues.

I suppose once you know your O2 sensor is feeding dynamic data to your ECU, you could start to tailor your fuel map to achieve a stochiometric condition across the fuel-map.

Curious why not using original-spec MAF sensor?

If you suspect vacuum leaks, get a decent smoker, turn out the lights, and break out the penlight.

 

Although the maf came from a corvette it’s the same part number as a f body.
MAF units from 86-89 models output a simple analog signal instead of using frequency modulation like the 1985 units. So as long as your not running one from a 85 it should be fine.

YEAR ENGINE OE #
Camaro Z28
1989-1988 5.0L (F) 305" 10055877
1987-1986 5.0L (F) 305" 14094712
1985 5.0L (F) 305" 14081243
1989-1988 5.7L (8) 350" 10055877
1987-1986 5.7L (8) 350" 14094712
Corvette
1989-1988 5.7L (8) 350" 10055877
1987-1986 5.7L (8) 350" 14094712
1985 5.7L (8) 350" 14081243

 

Car was a restoration; the MAF was already in it & worked, so I didn't change it.

 

Replaced Oxygen sensor; all symptoms disappeared. Learned that shank on sensor with Flowmaster muffler is longer than shank on stock 02 sensor for this vehicle. Thank you for your help.

 

Is the new sensor a longer-shank design?

I'm a little confused about the mention of the muffler, as the the O2 sensor is usually found far-upstream from the muffler.

 

For some reason, 02 sensor was non-standard. Not related to muffler, of course.