O2 sensors

[BOOGER]

My cars at Holden at the moment because the check engine light came on twice while driving home on Tuesday. They've told me the O2 sensors have packed it in. I've got Pacemaker 1 3/4 headers, high flow cats and a Sureflo 3.5 single catback. The headers and cats were only fitted a few months ago the catback almost a year ago. Are O2 sensors s@#ting themselves something that's going to happen on a regular basis now?

Just picked up the car and everything should be fine now. The Holden bloke told me the O2 sensors failed due to be fouled by melted silicon which had been used on the headers. Is it standard practise for exhaust shops to use silicon on the headers when fitting them?

[snapper5.7L]

Sounds absolutely bang on to me. I've got a similar setup on my SV8 (pacemakers + catback) and the car started almost like missing after a while. I thought it might be the O2 sensors so I just told Holden to replace them and it fixed it up, right as rain...even noticed better fuel consumption. I believe what happens is the metal in the exhaust before the sensor essentially breaks down over time and the deritus fouls the sensor giving shitty readings to the computer. Your car should feel a lot better to drive after getting them replaced. Just one of those things. Stainless exhaust should prevent it from happening again (mild steel breaks down over time).

[BADCV8]

Add me to that list also....Similar set up with Pacemakers etc..etc and o2 sensor on RHS has sh%t itself.

Only just found out about it last week and in the midst of arranging to get it sorted out.

Have also been told that fuel consumption will be improved along with general driveability.

While we are at it, what are they worth to replace ?

[Tyre biter]

I understand they all go belly up sometime after fitting a full exhaust system because the cats are different to standard, and (whilst it takes varying amounts of time it seems) the 02 sensors end up thowing the fault code.

Most either deal with it by way of a tune, or in the very least, have their tuner simply 'turn off' the rear 02 sensors.

Cheers

[SharkBiscuit]

Add me to that list also....Similar set up with Pacemakers etc..etc and o2 sensor on RHS has sh%t itself.

Only just found out about it last week and in the midst of arranging to get it sorted out.

Have also been told that fuel consumption will be improved along with general driveability.

While we are at it, what are they worth to replace ?


I saw an invoice yesterday for $165 from a holden dealer but I hear of some other folks on the forum going bosch while the're at it.

[Toddler78]

I dont think $165 is totally unreasonable, go to the O2 sensor thread from memory there are some higher prices charged in there. I beleive the bosch ones are about $100, but the oem holden ones would expectatly be more + fitting + clearing the fault with tech 2 (yes only 30 sec job but I bet they still charge).

not uncommon for the 02 sensors to shit themselves after headers have been fitted especially if they have been HPC coated as they are clearing all the lose crap out inside which unfortunatly kills the sensors.

[BOOGER]

Holden charged me $215 for the 2 sensors plus $60 to clear the code. The headers I've got are ceramic coated so if that has played a part in the sensors failing then I can only blame myself but if the sensors have been fouled with silicon used by the installer (as I've been told by Holden) then maybe I should be sending the bill to them?

[ratter]

Most installers will use o2 sensor safe silicon and if they have, they have not caused your problem.

Moving the o2 sensors which is what happens when extractors are fitted, can move the o2s to a different dew point of the exhaust. What this means is, the sensor may now be in a location that collects more moisture and when the ignition is turned on the heaters start to heat the sensor instantly, and the heating element may crack because of the moisture on it. When the heater stops functioning so will the sensor.

Some newer model cars are now controling the actual heating of the sensor so as to make sensor live longer so the car meets emission levels for a longer period of time

[BOOGER]

Ratter,

I hope that this is just the case. The installer is a forum sponsor and a good bunch of guys who I'd have no hesitation to use again so making an issue out of this with them is the last thing I want to do.

[FeralSS]

O2 sensors are a recurring problem with my 2001 series 2 SS ute.. Ive owned it for over three years, this is how it started

* car was pinging on regular unleaded (standard ss, with full exhaust/extractors/cats etc) so I changed the O2 sensors, car ran like a dream.. until [PS. installed Bosch O2 sensors this time]

* 6 months later - car seems to splutter and surge after I start it in the morning, not straight away, like 4 minutes after driving until the 02 sensors would warm up and the car would run normally.

I took it to Street Force (wangara, perth) and he said to only use GM factory O2 sensors (AC Delco), so I install those..


* Car continues to run sweet for about 5 months, decide to MAF-less tune car/intake mods etc.. makes awesome power avg 320hp @ wheels, 02 sensors registering fine (tuned at Street Force)

.. car runs like an absolute dream with the tune, the car I always wanted, but then a couple of months down the track the same 02 sensor problem, coughing, splutering surging.. rough idle?!? again!

* So this is where im up to now.. running Bosch sensors only from now on as they are half the price... my only guess is the 02 sensor position on my diffilippo headers, anyone else with experience with this prob please contact me


here are my ute specs:

2001 Series II VU SS
twin 2.5" exhaust, hi-flow cats, diffillippo extractors, top-gun leads, throttle-body coolant bypass, 4" inch MAF pipe, Kostecki cold air intake/airbox
MAF-less tuned @ Street Force, Wangara Perth (was very pleased with tune)

*please note I had this problem BEFORE and AFTER the tune

cheers

Ben

oh i should also add, I havnt any corrupting sealents around extractors/sensors etc.. the headers have been on it since 2001

[OPTIMUS]

Bosch ones are $83 at Repco

[scotty82]

I posted recently in the 02 sensor thread that has been running for a while as I am after the Bosch P/N's. Does anyone have the front and rear P/N's for the Bosch 02 sensors for the L98?

Any help would be appreciated
Thanks

[davox7]

I payed $60 each for ntk sensors at the local spares shop.

[OPTIMUS]

I posted recently in the 02 sensor thread that has been running for a while as I am after the Bosch P/N's. Does anyone have the front and rear P/N's for the Bosch 02 sensors for the L98?

Any help would be appreciated
Thanks

They are the same as LS1, Super6 Bosch # 0258 005 703

[scotty82]

They are the same as LS1, Super6 Bosch # 0258 005 703

Hi Mate

Thanks for that. So front and rear can use the same sensor? I have been told the OEM front and rear are different. Thanks.

Cheers
Scott

[pdbee]

My cars at Holden at the moment because the check engine light came on twice while driving home on Tuesday. They've told me the O2 sensors have packed it in. I've got Pacemaker 1 3/4 headers, high flow cats and a Sureflo 3.5 single catback. The headers and cats were only fitted a few months ago the catback almost a year ago. Are O2 sensors s@#ting themselves something that's going to happen on a regular basis now?

Just picked up the car and everything should be fine now. The Holden bloke told me the O2 sensors failed due to be fouled by melted silicon which had been used on the headers. Is it standard practise for exhaust shops to use silicon on the headers when fitting them?




I have been reading the O2 sensor thread for some time now

I have gone mafless on my LS1 WH Statesman, I am running Pacemaker headers, high flow cats and sports exhaust

The car was converted to mafless about 3 years ago by Dick at Dick’s Electronics in Sydney, about 3 months later I went OTRCAI, the performance was staggering, with a great intake growl

Approximately 1 year after going mafless, my engine started to run roughly and became a dog to drive, It was at it’s worst for about the first 10 minutes after starting.

I took the car back to Dick, who ran a diagnostic program and he told me the oxygen sensors were shot, He told me they were likely to be the original sensors and time to be replaced anyway

After replacing the sensors with Holden Genuine replacements, the car was as good as before

About 6 months ago it started again with the rough running and idle, the exhaust was very black, spitting black liquid all over the garage wall on start. The average fuel went to about 25 litres/100km

With such a break between the first known O2 sensor replacement by Dick and the next problem 6 months ago (18 month gap), I have discounted Silicon sealant and header length and dew points as a cause

I have replaced nine (9) O2 sensors in the last six months, each time with Holden Genuine parts

Last Friday week I went back to Dick’s, (I was using 33.5 litres / 100km and the exhaust pipes were BLACK, inside and out) He plugged his computer in to the system under the steering wheel and put an air ratio sensor into the exhaust just in front of the cat LHS.

We went for a drive and he told me the O2 sensors were dead again and suggested he try a few things.

He took the O2 sensors out of the equation but left them in to fill up the holes but he continued to monitor their performance. We drove from Alfords Point almost to Liverpool on the Heathcote Road, All the time he monitored the computer and his air percentage meter.


The further I drove the lower the the average fuel used reading went.

By the time we turned around, the average fuel used was 20 litres /100km
A brilliant improvement seeing I’d used half a tank when I got to his place that morning averaging 33.5 litres/100km

The next amazing thing was that the O2 sensors had come back to life but were only showing 800 millivolts. He told me that this was probably the cause of my problem. He said they should read 1.2 volts when operating correctly, thus with a lower voltage, they were telling the computer to run richer all the time. The richer they ran, the less voltage they showed, so they ran richer etc. etc

Conclusion, the Holden O2 sensors are all running at lower voltage than needed

We have left the O2 sensors turned off and the car is running purely on the mafless tune, the car is as good as ever with no O2 sensors.

Dick assures me there will be no detrimental effect on the car with no O2 sensors,

I am currently running at 15 litres/100km around town

Hope this helps some of you

[macca33]

So, was it Dick's tune that caused all those sensor failures, or was it something else?

[pdbee]

So, was it Dick's tune that caused all those sensor failures, or was it something else?

The car ran perfectly for 18 months on his tune!!!

See comment above:-
"Conclusion, the Holden O2 sensors are all running at lower voltage than needed"

What he is saying is that the Holden O2 sensors are not right

The worrying concern for me is that all the 9 replaced sensors were purchased from the same place, the guy claims to use only Holden genuine parts.................Maybe not true, I don't know, He has never given me back the faulty ones, claiming he was sending them back to GMH

Dick's tune is brilliant and he doesn't flog the sh@t out of your car on a dyno to get it going, It is done in real time on the road

His tunes hold quite a few drag records for 'unopened cars' and 'heavily modified cars' like ICULKN

My car is putting out over 300kw in it's current configuration. Not bad for a 2002 barge

[surfwagon]

I had problems with my O2's in my VS super6 and went thur 4 Holden (AC) O2's which didn't last more than about 2-3 months before packing it in.
Then I purchsed 2 from my local parts supplier (NTK) made by NKG and they were still working perfect when I sold the car (about 10months old).
The first thing I noticed was the shape was completely different to what Holden were selling me so started looking on websites to make sure that they were ok.
On the Bosch site ( http://www.bosch.com.au/content/language1/html/4566.htm ) I noticed that the O2's I was sold from Holden are actually 10yr old versions and when a mate bought a couple for his VS calais he got given the later vz versions and they worked perfect for his car.
The reason I bought this up is that when you buy these things sometimes you could be getting old stock that doesn't work like it is supposed to with newer wiring/ecu's etc.

[swingtan]

"Conclusion, the Holden O2 sensors are all running at lower voltage than needed"

What he is saying is that the Holden O2 sensors are not right



Well... Interesting comment there, mainly because the "800mv" you mentioned earlier is an OUTPUT voltage, not a "running" voltage. If you understood how a Narrow Band O2 sensor worked, then you would know that quoting a single voltage to say an O2 sensor is "bad", is just plain wrong. If I had someone try to tell me that I'd leave the shop and not return.

What I'd like to hear would be something like this...



I've measured the switching performance of the O2 sensors and found that they are slow or not switching at all. This is a good indicator that the sensors have become clogged or have been contaminated.


Trying to diagnose an O2 saying it only reaches 800mV is like looking up at the sky to tell which star is closer.

If the O2 sensors were both reading 800mV then I'd say that the mixture was probably running in a "richer than Stoichiometric" condition. If you really want to check a Narrow Band O2, check the switch rate when the car is running in closed loop mode. Which leads me to the next point....

Many, if not nearly all, MAFless tunes are set up to run in a mode called "Semi Open Loop". This means they only use the O2 sensors part of the time, the rest of the time they use the "correctly" adjusted air flow maps. If these maps are out, in an effort to fudge a lean cruise or simply not done correctly, then if the PCM goes into Closed Loop, it will learn to trim the fuel to correct for the poorly set up fuel / air maps. If the time spent in CL mode is small, it could take some time for the trims to build up. The other thing is that it is possible for the trims to affect the commanded fueling, even in OL mode.

Given that many, many Original Holden O2 sensors are still in use and performing well and given that you have gone through so many, I'd be saying that either the diagnosis of the faulty O2's was wrong, or there is something causing the O2 sensors to fail. I find it difficult to believe that so many sensors would fail in such a short time.

Simon.

[pdbee]

Well... Interesting comment there, mainly because the "800mv" you mentioned earlier is an OUTPUT voltage, not a "running" voltage. If you understood how a Narrow Band O2 sensor worked, then you would know that quoting a single voltage to say an O2 sensor is "bad", is just plain wrong. If I had someone try to tell me that I'd leave the shop and not return.

What I'd like to hear would be something like this...



Trying to diagnose an O2 saying it only reaches 800mV is like looking up at the sky to tell which star is closer.

If the O2 sensors were both reading 800mV then I'd say that the mixture was probably running in a "richer than Stoichiometric" condition. If you really want to check a Narrow Band O2, check the switch rate when the car is running in closed loop mode. Which leads me to the next point....

Many, if not nearly all, MAFless tunes are set up to run in a mode called "Semi Open Loop". This means they only use the O2 sensors part of the time, the rest of the time they use the "correctly" adjusted air flow maps. If these maps are out, in an effort to fudge a lean cruise or simply not done correctly, then if the PCM goes into Closed Loop, it will learn to trim the fuel to correct for the poorly set up fuel / air maps. If the time spent in CL mode is small, it could take some time for the trims to build up. The other thing is that it is possible for the trims to affect the commanded fueling, even in OL mode.

Given that many, many Original Holden O2 sensors are still in use and performing well and given that you have gone through so many, I'd be saying that either the diagnosis of the faulty O2's was wrong, or there is something causing the O2 sensors to fail. I find it difficult to believe that so many sensors would fail in such a short time.

Simon.

You're talking way above my head, open loop, closed loop, semi-open loop.
Stoichiometric condition

All I know is

1. He monitored the O2 sensors while they were OUT of the program and they recovered

2. the car ran perfectly for 18 months on the tune I had done then does 9 O2 sensors in 6 months

3. the car is running perfectly now with NO O2 sensors working in the tune

Man, I'm an accountant and I know FA about tuning cars, I only wrote and told the people of my experience in the hope it could lead some of them in the right direction

One guy on an O2 thread (here I think) said that he'd heard that you could run mafless with no O2 sensors, I agree, I'm now doing it

[macca_779]

Well... Interesting comment there, mainly because the "800mv" you mentioned earlier is an OUTPUT voltage, not a "running" voltage. If you understood how a Narrow Band O2 sensor worked, then you would know that quoting a single voltage to say an O2 sensor is "bad", is just plain wrong. If I had someone try to tell me that I'd leave the shop and not return.

What I'd like to hear would be something like this...



Trying to diagnose an O2 saying it only reaches 800mV is like looking up at the sky to tell which star is closer.

If the O2 sensors were both reading 800mV then I'd say that the mixture was probably running in a "richer than Stoichiometric" condition. If you really want to check a Narrow Band O2, check the switch rate when the car is running in closed loop mode. Which leads me to the next point....

Many, if not nearly all, MAFless tunes are set up to run in a mode called "Semi Open Loop". This means they only use the O2 sensors part of the time, the rest of the time they use the "correctly" adjusted air flow maps. If these maps are out, in an effort to fudge a lean cruise or simply not done correctly, then if the PCM goes into Closed Loop, it will learn to trim the fuel to correct for the poorly set up fuel / air maps. If the time spent in CL mode is small, it could take some time for the trims to build up. The other thing is that it is possible for the trims to affect the commanded fueling, even in OL mode.

Given that many, many Original Holden O2 sensors are still in use and performing well and given that you have gone through so many, I'd be saying that either the diagnosis of the faulty O2's was wrong, or there is something causing the O2 sensors to fail. I find it difficult to believe that so many sensors would fail in such a short time.

Simon.

Thats not quite accurate Simon. Semi Open Loop is only available in EFI LIVE's Custom OS's. What it refers to in essence is that when you command 14.63 you run with STFT corrections. At any other AFR its OL. LTFT's are not utilised at any time with a Semi Open Loop OS.. Its just not physically able to be supported in the OS's as it clashes with B3647 I'm told.

Retaining LTFT's would be considered CL even with PE and Lean Cruise factored in. With Lean Cruise being timer and speed enabled there are opportunities to have 14.63 and thus CL conditions met at areas where later lean cruise can be applied. That means if LTFT's are saved at for example +2% 40kpa/2000rpm while in CL. That +2% will also be applied when in lean cruise at 40kpa/2000rpm OL even though you may be commanding 16.00.

I'm 99% sure HPTuners (VCM Suite) doesn't have Semi Open Loop capability. Their COS for MAFLESS cars pretty much revolves around re enabling the High Octane Spark table and that's about it. They effectively run CLSD like EFI LIVE's OS1 which no one really uses as we have much better ones like OS5 :)