o2 sensor malfunctioning?

[Bizmark]

My car seems to run rich at idle, to the point that it has strong exhaust fumes. Fuel econ isn't that good either. I was told that my o2 sensor could be the culprit. Had a look at it in EFILive, voltage was quite stable around 900mV, the test was done while the car was idling, at operating temp. Pic included.

 

[delcowizzid]

evaluation LOL download tunerpro RT http://www.tunerpro.net/download/SetupTunerProRT_v500_7532.exe and grab the vr ADX for logging from here delcohacking.net • View topic - .ads .adx .adl files for aldl logging. and then you have all sensors on display

 

[Brett_jjj]

If the 02 sensors are old,Id replace them anyway,they are only good for around 100,000 k's.Try to buy genuine ones from holden instead of cheap ones from ebay, unless they are bosch or delphi etc.If you can get one of these brands cheap on ebay,then go for it.They are as good as genuine ones.

 

[Bizmark]

evaluation LOL download tunerpro RT http://www.tunerpro.net/download/SetupTunerProRT_v500_7532.exe and grab the vr ADX for logging from here delcohacking.net • View topic - .ads .adx .adl files for aldl logging. and then you have all sensors on display

Cheers, i had that program but couldn't find any adx files. Is there something wrong with EFIlive?

If the 02 sensors are old,Id replace them anyway,they are only good for around 100,000 k's.Try to buy genuine ones from holden instead of cheap ones from ebay, unless they are bosch or delphi etc.If you can get one of these brands cheap on ebay,then go for it.They are as good as genuine ones.

Thanks for the tip. I have no idea when the o2 sensor was last changed, if at all.

 

[Cheap6]

High O2 sensor voltage does indicate rich.

A working O2 sensor and PCM will have the voltage oscillating around ~450mV but only with the sensor hot and the engine off idle.

I would:

Check the O2 sensor operation away from idle eg. at light load operation eg. normal driving with gentle accel. and cruise.

Perform a check for any fault codes.

With the engine hot, clear the PCM memory - disconnect the "Eng Comp" fusible link, found near the battery, or -ve battery terminal for ~10 seconds - disconnect the O2 sensor and then run the engine and see if the rich mixture is still identifiable out of the exhaust. Then reconnect the O2 sensor and watch the O2 sensor voltage output again. Clearing the PCM resets the learned adjustments made by the PCM back to the default values.

It could be a faulty O2 sensor but the O2 sensor reading may just be a symptom. Maybe also look at:

Coolant temp. sensor (using additional sensor readings from ALDL log from ^^). Also fault code(s).

Sticking (open) thermostat.

Leaking injector(s) or fuel pressure reg.

 

[Bizmark]

While driving this morning, the check engine light came on for about 10 mins. Checked for fault codes when i got home and code 45-o2 sensor rich came up. Exhaust fumes seem to have a stronger fuel smell to it now.

High O2 sensor voltage does indicate rich.

A working O2 sensor and PCM will have the voltage oscillating around ~450mV but only with the sensor hot and the engine off idle.

I would:

Check the O2 sensor operation away from idle eg. at light load operation eg. normal driving with gentle accel. and cruise.

I'll give that a go when i have access to a laptop again

Perform a check for any fault codes.

With the engine hot, clear the PCM memory - disconnect the "Eng Comp" fusible link, found near the battery, or -ve battery terminal for ~10 seconds - disconnect the O2 sensor and then run the engine and see if the rich mixture is still identifiable out of the exhaust. Then reconnect the O2 sensor and watch the O2 sensor voltage output again. Clearing the PCM resets the learned adjustments made by the PCM back to the default values.

It could be a faulty O2 sensor but the O2 sensor reading may just be a symptom. Maybe also look at:

Coolant temp. sensor (using additional sensor readings from ALDL log from ^^). Also fault code(s).

What sort of voltages would be good for that sensor?

Sticking (open) thermostat.

Car gets up to temp quick enough so i doubt that's an issue, may look at it if i can be bothered

Leaking injector(s) or fuel pressure reg.

How would i check for leaking injectors or fuel pressure reg issues?

 

[Z2TT]

What about ECU Capacitors? I've heard lots of people having EFI related problems (Such as bad fuel ec), and replaced defective caps on ECU which helped.
I thought the ECM gives out an error code via CEL when the o2 sensor goes bad, which was what I was told here on JC.

Clean Injectors?

 

[RX25SE]

While driving this morning, the check engine light came on for about 10 mins. Checked for fault codes when i got home and code 45-o2 sensor rich came up. Exhaust fumes seem to have a stronger fuel smell to it now.

A nice O2 voltage would fluctuate between 0.2v lean and 0.9v rich. The graph would show the mixture going rich then lean in a wave. A good O2 sensor will fluctuate quickly and respond instantly to a sudden wide open throttle.

I would follow the advice given above. It sounds like a fault in another system that's causing a excessively rich mixture.

 

[Bizmark]

I just realized i had another screencap from EFI live, showing coolant temp sensor voltage along with the corresponding coolant temp.



Also, would an issue with the fuel pressure regulator, or leaking injectors be able to be identified with a fuel pressure test? Or is there a DIY method I can do at home?

 

[delcowizzid]

pull the fuel reg vacuam hose off if it smells like petrol or petrol comes out of it when you turn the key on its fubar.injectors lift the rails with injectors still in them and sit some handy towel under them and prime system with key and check for leaks