97 P38 Oxygen Sensor issue?

[LavisLane]

Hey all,

Have been struggling with an intermittent problem for a while and next on the list is O2 sensors.

New ones for my 97 HSE are around $750 a pair (?!) and since no one knows if it really is the sensors causing the issue (intermittent is too hard to pin down) im not keen on dropping $750 on it.

Q - does anyone know of a cheaper option?! Lots online for around $100 but seems like a tricky issue with P38's from a dig round the forums.

Q - can anyone in Sydney with a Gems P38 (pre cat O2 sensors) swap sensors with me for a few days? I'll do the hard work and supply a carton of your choice ;)

Thanks for any feedback,

Dave

[ytt105]

I didn't think the GEMS had o2 sensors. Mine doesn't.

[bee utey]

I didn't think the GEMS had o2 sensors. Mine doesn't.
Early ones didn't, later ones did.

[DT-P38]

Can help... I have some brand new ones under the house (advised by a dick head that I needed them replaced, however car is a 95 and pre-sensors).

If you want to pm me an address, I can mail them to you express post... You would get them next day.

We can work out a price if you need to buy them afterward, or just return them if yours check out ok.

Hoo roo, Dave

[LavisLane]

Can help... I have some brand new ones under the house (advised by a dick head that I needed them replaced, however car is a 95 and pre-sensors).

If you want to pm me an address, I can mail them to you express post... You would get them next day.

We can work out a price if you need to buy them afterward, or just return them if yours check out ok.

Hoo roo, Dave

Legend :)

Thanks Dave

[Hoges]

If you have a half decent multimeter and a propane torch you can rig up a test for your O2 sensors and check them out as follows

O2 Bench test - YouTube

cheers

[glenhendry]

Or else, any cheap OBDII scanner should be able to show you real time values from the O2 sensors. They normally fluctuate between 0.1v and 0.9v. Make sure that the fuelling system is in closed loop operation. If I run on LPG for a while, my petrol fuelling goes to Open Loop fuelling, ignoring the O2 sensors because a fualt has been logged saying that they are faulty. As soon as I clear the ECM fault, all goes back to normal and the ECM re-learns the correct petrol mixture by listening to the O2 sensors again.

[bee utey]

GEMS sensors on the '97-'98 P38 aren't 0-1 volt. They are either 0-5V or 5-0V, totally different to the Bosch sensors.

[LavisLane]

So, Dave DT-P38 kindly sent me his spare to try out but are the wrong plug fit and i'm guessing from what i've read on the forums measure in the wrong voltages (?) so, i'm looking around for somewhere to buy a new set and have come accross sites like this one;Discovery Range Rover Freelander Lambda Sensor (http://www.worldcarparts.co.uk/CarParts/tabid/144/ProductID/127/language/en-GB/Default.aspx)

Range Rover P38A 02 Oxygen Sensor Exhaust Parts Available from RoversNorth.com (http://www.roversnorth.com/store/c-462-02-sensors.aspx)

Confusing thing is that to buy them from any LR parts reseller here in aus, i'm looking at around $700 - $800 a pair. Online they are all going for around $180 to $350 a pair!? Sounds too good to be true - am i missing something?!?

[glenhendry]

You shouldnt shell out until you know that yours are definitely broken. I made that mistake, bought some cheap ones from a US based online auto shop and had to send them back, only to find that my original ones were fine, but had been ignored by the ECU due to a stored fault.

Connect a diagnostic scanner and check the values coming into the ECU from the sensors. Then you will know what you are hunting for.

[PhilipA]

The Uk site you linked is AFAIK wrong.
Up to Thor ie 95to 99 , the RR o2 sensors were Titania sensors not Zirconia.

Have a look here
Just Lambda, Landrover lambda sensors, Bosch and NTK zirconia and titania sensors by post (http://www.lambdasensor.com/main/lrover.htm)

Regards Philip A

[LavisLane]

O2 sensor tests
Thanks to everyone with advise on how to test these. A few mechanic's have already done this and advise they are fine, however, the power loss is intermittent (lasting 1 1/2 mins usually) so I'd need to be testing them while it's happening. Not practical without live software running?

iPhone OBDII data capture
Not sure if i'm more or less confused after capturing some data of the intermittent power loss recently.

Check out the graph attached. I captured this using my iPhone and the Rev OBDII app DevToaster - Rev - iPhone app development, Great iPhone apps, and more (http://www.devtoaster.com/products/rev/). The app is as limited as one would expect, with some of the values not working at all (a general P38 issue?) the stand out value to me is the "Fuel Trim Short Bank 1" value that is possibly changing more than it should (?).

Before I go any further, I have to advise that I'm still trying to work out what the "Fuel Trim Short Bank 1" is... After a little research I gather that it's something to do with the ECU's ability to change mixture based on values coming from sensors. I'm guessing that the O2 sensors play a big part in this and may be a cause of errant values. However, i'm not sure what correct values look like, so this may all be me on a wild goose chase, not knowing what a goose even is! :o

Anyway, the graph is pretty with lines going up and down and looks like the how the engine feels during the intermittent power losses. I've multiplied some of the values to have them in line with each other for easier comparison.

Next
- Can anyone recommend good PC software to capture live engine data? Capturing actual O2 sensor data might be helpful.
- Anyone see anything there that points to anything?

Thanks all,

Dave

[bee utey]

What limited experience I have says a "short term fuel trim" under 5% is fine, according to my scanner on newer vehicles than yours.

[glenhendry]

I use the android app called Torque, which talks to a bluetooth ODBII adaptor. It logs data. The adaptor I have is crappola, and often refuses to connect to the phone.

[LavisLane]

iPhone FTW ;)

[PhilipA]

I would think that the graph doesn't tell much about the O2 sensors as the sampling time is 2 seconds, and O2 sensors should react several times a second.
Having said that the fuel trim appears to average around zero which one would expect on a motor with MAF and other sensors in good condition, as this should be around lambda.
So it appears to me that the sensors are doing something , but whether they are slow or not cannot be seen. AFAIK sensors usually become slower as they age.

Regards Philip A

[TheTree]

Resurrecting an old thread here.

I think I may have an O2 sensor problem and reading around and looking at this thread and the rr.net one linked below, I think I may have the wrong sensors fitted

GEMS Titania O2 Sensor Readings? (http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/20157-gems-titania-o2-sensor-readings.html)

My readings are the same as that thread, cycling between 6.4 and around 0.3 but it seems they should be 0-5v from what I read here

So either ERR1834 or AMR6244 ? Looking at the page Philip A posted a link to, they seem to be the same universal number(fit) so I am now wondering what the difference between them is.

Edit: Upon further investigation the only difference seems to be the plug and I have the earlier type plug

According to Microcat, to VA 350483 is ERR1834 and then to WA 410481 is AMR6244.

I should add I have a tornado chip fitted as well.

Steve