Can O2 snsr go bad w/o CE light coming on?

[pwalk100]

The stomp test is now telling me nothing is wrong (even after resetting and driving). I can't find any vacuum leaks, and my emissions test was as follows:

High Speed
HC CO
Standard 220 1.20
Reading 187 0.54

Idle
HC CO
Standard 220 1.20
Reading 407 0.53

Last yead my readings were significantly different
High speed HC = 20
High speed CO = 0.01

Idle HC = 96
Idle CO = 0.00

Two questions:
1) Is it possible the FI computer was doing a bad job b/c is was getting that strange output from the stomp test (2 1 2 1 2 1 - over and over again, until I disconnected the battery)

2) Can an O2 sensor be faulty w/o the computer recognizing the failure?

Thanks in advance for the help.

-Phil
93 525iT

[Bill R.]

misfire at idle caused by most likely a bad spark plug or oil in one of the spark plug tubes causing the coil to misfire...If it was a vacum leak your co would be even lower and high hc at idle indicates a misfire.... If you had a bad exhaust valve it would probably be a lot higher so I'd check the plugs and coils first.

The stomp test is now telling me nothing is wrong (even after resetting and driving). I can't find any vacuum leaks, and my emissions test was as follows:

High Speed
HC CO
Standard 220 1.20
Reading 187 0.54

Idle
HC CO
Standard 220 1.20
Reading 407 0.53

Last yead my readings were significantly different
High speed HC = 20
High speed CO = 0.01

Idle HC = 96
Idle CO = 0.00

Two questions:
1) Is it possible the FI computer was doing a bad job b/c is was getting that strange output from the stomp test (2 1 2 1 2 1 - over and over again, until I disconnected the battery)

2) Can an O2 sensor be faulty w/o the computer recognizing the failure?

Thanks in advance for the help.

-Phil
93 525iT

[pwalk100]

in the sparkplug tubes. It's been there for a while though, and I've ever had problems. Perhaps it's time to try and correct it. Thanks for the thoughts. I'll spend some time taking a look.

-Phil

misfire at idle caused by most likely a bad spark plug or oil in one of the spark plug tubes causing the coil to misfire...If it was a vacum leak your co would be even lower and high hc at idle indicates a misfire.... If you had a bad exhaust valve it would probably be a lot higher so I'd check the plugs and coils first.

[pwalk100]

Just a quick note to close out this thread for the archive...

I replaced the O2 Sensor and cleaned up the plug caps (a couple of them had some slight oil residue). I threw in some of the "guaranteed to pass" stuff just for good measure, and I passed with flying colors. Thanks for the help.

-Phil

in the sparkplug tubes. It's been there for a while though, and I've ever had problems. Perhaps it's time to try and correct it. Thanks for the thoughts. I'll spend some time taking a look.

-Phil