Fuel Economy, 02 Sensor replacement. L67

[Vy S SC]

Hi guys,

Currently my VY S Pack L67 is sitting around 17-19/100Km. This is all city driving with minimal highway driving. I believe this is pretty high for a V6, even though its supercharged.

It has a Mace Cold air intake and is running a 10psi pulley.

Plugs, Leads have been changed less than 10,000km ago.
Fuel filter was replaced 15,000Km ago. How long do these suckers last/or how often should they be replaced?

Im obviously running 98Ron fuel from BP. No codes are evident and the Holden mechanics said not to change 02's unless there is warning/fault code.
The car has done 175,000Km.

Im looking at swapping the 02 sensors as ive found they aren't that expensive to replace if i get aftermarket brands.

Holden wanted close to $190 per sensor, I obviously need 2.

I've jumped on ebay and found these:

2x NEW Holden VS VT VX VY VZ VE LS1/2/3 Oxygen Sensor | eBay

eBay Australia: Buy new & used fashion, electronics & home d

Has anyone tried any of these 2 brands of 02 sensors, or can anyone help me with my situation.
Thanks

[cander24]

Many people don't replace o2 sensors until they completely die due to the cost of them. Apparently they should be replaced every 100,000kms though. Your city fuel usage does seem a little high.
In my opinion, this is one sensor I would NOT buy other than genuine GM/AC Delco as many aftermarket copies cause more trouble than they're worth.
If you're interested, I have a pair of brand new GM 4 wire o2 sensors to suit your VY l67 for $220. PM me if you're interested.
Cheers

[Vy S SC]

Thanks for the quick reply cander24,

I just spoke to my mechanic and he can get them at trade for around that price. I appreciate your help though.

I'm still leaning towards the aftermarket ones and saving $120ish. What is the worst that could happen? Wouldn't I be able to plug my old ones back in, worst case scenario?

Thanks

[Crisis63]

I would not have any issue with after market sensors from a reputable manufacturer.
Just replaced them on my CV8. Initially got the wrong ones although we ordered the correct ones. They were wide band. In the wrong box by the look. I ended up with a pair of NGK 4 wires at $50 each.

[FATMOE]

The aftermarket ones I purchased on eBay for $79ea failed after 3 days. Stick to the genuine sensors and don't look back.

[Vy S SC]

Where they from a reputable seller champ? Did they cause further problems or? What happens when they fail? Does your fuel just go through the roof or?

Cheers

[FATMOE]

They were from a seller who had a good reputation....only one side failed caused a low voltage. Fuel consumption was still reasonable but my car felt like shit. Shuddering on idle, loss of acceleration and stalling down to 300rpm. I put my genuine's back in and now it feels better and I'm on about 13l/100km in a lightly modified ls1 around town.

[D3CID3R]

Repco brand $35

[PRAVX II S]

How do you know if the o2 sensor is gone?
Dont guess work mate you end up wasting money.
Check the o2 sensor if its working properly.
Put it on the graph and look at the cross counts and voltage its working at. Should be a constand up and down voltage from 100mv-750mv-1v. This is only true in closed loop mode or when the o2 sensor is heated to operated temp.
There could be other factors unmetered air getting in, could be your sender unit from the tank, Holden has many problems with wrong reading gauges.

[Vy S SC]

I forgot to check Repco! Thanks D3CID3R.

PRAVX II S, thanks for the detailed response. Do most mechanics have this tool to check o2 sensors voltage?
I just thought the cheapest thing would be to buy a set of o2's for $80 and to see if that helps, if not its only $80 that i'm down.
What concerned me is the high KM's of the vehicle (174,xxxkm), someone above mentioned they should be replaced every 100,xxx.

In regards to the 'unmetered air', are you refering to the sensor in my air filter enclosure not reading properly?

Cheers

[PRAVX II S]

I forgot to check Repco! Thanks D3CID3R.

PRAVX II S, thanks for the detailed response. Do most mechanics have this tool to check o2 sensors voltage?
I just thought the cheapest thing would be to buy a set of o2's for $80 and to see if that helps, if not its only $80 that i'm down.
What concerned me is the high KM's of the vehicle (174,xxxkm), someone above mentioned they should be replaced every 100,xxx.

In regards to the 'unmetered air', are you refering to the sensor in my air filter enclosure not reading properly?

Cheers

Unmetered air, Like leaking inlet manifold/Exhaust manifold, vacuum leaks, and yes maf sensor can be reading wrong.
Go to a good auto-elec almost all have a diagnostic machine that can read the right information for your needs.
Also you can check your own o2 sensor your self with a multi meter its a rough check but it will give some information on whats happening.
Have a search of the net there is loads of info on the o2 sensor.

[krizza]

From previous experience it is well worth replacing O2 sensors if they have done plenty of kms (ie > 100K ). The problem with them is as they get old they become slow to respond to changes in a/f ratio long before they completely die and throw an error code. This causes overly rich mixtures and the subsequent poor fuel economy issues.

For the cost it is well worth doing. Also remember to reset your ECU to clear any longterm fuel trim values it has learned after replacing them.

I have just purchased a pair for my VY as it has done 160K now, and will be replacing them shortly.

[PRAVX II S]

From previous experience it is well worth replacing O2 sensors if they have done plenty of kms (ie > 100K ). The problem with them is as they get old they become slow to respond to changes in a/f ratio long before they completely die and throw an error code. This causes overly rich mixtures and the subsequent poor fuel economy issues.

For the cost it is well worth doing. Also remember to reset your ECU to clear any longterm fuel trim values it has learned after replacing them.

I have just purchased a pair for my VY as it has done 160K now, and will be replacing them shortly.

As an auto-elec it is best to test the o2 sensor. You can test them on the graph to see how fast they work hence the cross count. No point changing a working part.
I have had mine over 100k and counting.

[Vy S SC]

From previous experience it is well worth replacing O2 sensors if they have done plenty of kms (ie > 100K ). The problem with them is as they get old they become slow to respond to changes in a/f ratio long before they completely die and throw an error code. This causes overly rich mixtures and the subsequent poor fuel economy issues.

For the cost it is well worth doing. Also remember to reset your ECU to clear any longterm fuel trim values it has learned after replacing them.

I have just purchased a pair for my VY as it has done 160K now, and will be replacing them shortly.

Let us know how you go champ, i'd be interested to see how your consumption goes.

[Crisis63]

Do most mechanics have this tool to check o2 sensors voltage?

Most mechanics should have an OBD scan tool of some type. It is pretty impossible for anyone to correctly diagnose cars with onboard diagnostics without one and they are increasingly affordable. There is even an app for IPhone/pad!
With this they will be able to check the voltage and the rate the sensors are working. Seriously to mess around or replace sensors without checking them first could be a complete waste of money.

[Decicrate]

A great read here for o2 sensors. http://www.bosch.com.au/content/languag ... tion_A.pdf

At the back of the PDF there is a part number reference and a replacement guide for each sensor.



Page 11

Simplified Test Procedure
Locate the oxygen sensor and determine the wiring layout. On heated sensors check for heater element continuity, adequate 12 volt supply to
heater and correct ground when the engine is running.
Note - Many late model vehicles have the ground circuit of the oxygen sensor heating element controlled by the engine management ECU for
sensor temperature control purposes. Do not supply direct voltage or external ground to these circuits.
With engine speed at ~ 2000 RPM the sensor voltage should be seen to cycle smoothly between 100 – 900 mV (0.1 – 0.9 Volts) approximately
eight times or more every ten seconds as shown.
A contaminated or tired sensor will be slow to cycle between the sensor voltage limits and may not generate the full potential of 900 mV. It may
also be noticed that the lean swing may drop to zero voltage.
Remember!! – The oxygen sensor is a battery, a sensor that generates 900 mV constantly is generally not faulty. Faulty sensors, like a failing battery,
will be slow to cycle between the control limits and be generally slower to react to mixture changes.


Page 12
Whilst there are many factors that will contribute to accelerated oxygen
sensor failure, it should be remembered that an oxygen sensor is a
wearing part with a specific service life not unlike a platinum spark
plug. T
he oxygen sensor should have a service life ranging from 50,000
Km - 160,000 Km dependant on sensor design, however this can be
dramatically reduced by various conditions including overheating of
the sensor, chemical poisoning and impact damage.
Excluding physical damage, the majority of these conditions will result
in the failure of the ceramic thimble by affecting its porous nature.
This will result in a sensor that is slow to react to mixture change as
shown below. A slow sensor will tend to make the air / fuel ratio of the
vehicle drift rich.

Sensor Voltage Output
Normal Sensor - Voltage “cycles” between 100 & 900 mV. The average
output from the Oxygen Sensor will be ~ 450mV.

Slow, Contaminated or “Tired’ Sensor
Voltage slowly builds up and then rapidly drops off. The effect is that
the average will drop causing a rich condition.
Important facts about Oxygen Sensors.

Oxygen Sensor life spans will vary between vehicle and sensor designs,
and are effected by many factors including fuel quality and vehicle
operational characteristics.

Oxygen Sensors should be checked and/or replaced at -
50,000 km for single and two wire sensors.
80,000 km for three or four wire heated sensors.
160,000 km for planar type sensors

Oxygen Sensors can be contaminated in many ways including -
Lead fouling from incorrect fuel.
Severe carbon/oil fouling from engine/emission control defects.
Contamination from silicon products.

Thermal stress damage [fracturing of the ceramic thimble] from
excessive water in the exhaust, ie- blown head gasket.
Contamination of the Oxygen Sensor basically results in the coating
of the platinum electrodes and therefore insulates them.
**NOTE** - Oxygen Sensors cannot be cleaned!!

Oxygen Sensors will die of “old age”, they are a wearing service
part like a platinum spark plug.

As the Oxygen Sensor deteriorates over time, or is contaminated
the output from the sensor “slows down”. This causes the “average”
that the fuel management system calculates to reduce.

The lower average gives the impression that the engine is lean and
the fuel management system overcompensates to rich.

Due to the fact that the engine will operate in a rich condition at
all times, fuel consumption is naturally higher

[colgf]

check your rubber vacuum lines under the throttle body , theres a few of them , they tend to perish & come off the metal spigots. I have found twice on my L67 they have come off in this area of the engine.