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1995-2002 Range Rover P38A
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Discussion Starter #1
Hi

Being somewhat disappointed with no response on the Blackbox solutions BBS, I thought I'd try here ...

I used the RCL to try and find the troublesome fault on my 4.6 2000 RR.

According to Rave, the O2 sensors and / or the MAF sensor would probably log a fault code if they were faulty. How likely is it that one of these sensors could be faulty and not log a fault?

I viewed an O2 sensor log file (captured csv data) where the O2 sensor value drops very low, in some instances to 0v. Does this indicate a faulty sensor? or could it be caused by a faulty fuel flow, eg blocked injectors or (what I think I have as a problem) faulty emission control?

When viewing the data live, the O2 sensors tend to be opposite each other in value, eg if the left bank O2 sensor is .11 the right bank O2 sensor may be .79 then as they switch the values may be similar but transposed eg left bank is .79 and right bank now .11. Is this normal?

I noticed that the O2 readings switch levels approx every second, I believe (From reading RAVE) this is normal. However in my csv data there is the occasional "gap" of two seconds where the level change does not take place. See attached image for a portion of O2 sensor switching. The orange and blue lines are the O2 level changes.

My guess is this is representative of a fuel problem that I think I have

What is the RCL Lambda reading? I thought a lambda value was the value of the O2 sensor reading?

Kind regards

Peter
 

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2010-2012 Range Rover MkIII / L322
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The GEMS engine will switch between 0 and 5v in a regular pattern provided the engine has reached operating temperature and you are not adjusting RPM. So at idle, you should have a nice even pattern on the graph of 2 sensors switching between 0v and 5v.
 

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Rich998a said:
The GEMS engine will switch between 0 and 5v in a regular pattern provided the engine has reached operating temperature and you are not adjusting RPM. So at idle, you should have a nice even pattern on the graph of 2 sensors switching between 0v and 5v.
He has a 2000 year so that would be a Bosch rather than GEMs system. so O2 sensors should switch between about .1 and .9 volts every second at idle. Yes it would be normal for the banks to alternate.

What are the other lines in the graph? I'm not sure if the RCL works the same, but when use a pc based OBD scanner if you try to monitor too many pieces of data the refresh rate drops considerably and as such you do not see the all the changes which could account for the straight lines. Try, if possible, just monitoring live data for one O2 sensor at a time. The other way to check O2 sensors much more accurately is with a oscilloscope.

How old and how many miles are there on the sensors? It is normally believed 100k is the normal life. If you do replace make sure you do not use cheap aftermarket ones -they do not work on the RR - stick to Bosch - same with MAF.

You can test the MAF quite easily using RCL - info here - http://rangerovers.net/forum/viewtopic. ... 4&start=15
 

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Discussion Starter #4
Hi

What are the other lines in the graph?
I do not recall now what the other lines were. I included the image to display the O2 changes. If if is important, I can regenerate the graph from the captured csv data.
I'm not sure if the RCL works the same, but when use a pc based OBD scanner if you try to monitor too many pieces of data the refresh rate drops considerably and as such you do not see the all the changes
I think the RCL captures the data ok. The laptop I am using is reasonably fast.
which could account for the straight lines.
The straight lines are data values that do not change much during the data capture.
Try, if possible, just monitoring live data for one O2 sensor at a time.
AFAIK that's not possible with the RCL.
The other way to check O2 sensors much more accurately is with a oscilloscope.
Don't have a scope, but if there is something to be gained from a scope test I *think* I can borrow one.
How old and how many miles are there on the sensors? It is normally believed 100k is the normal life. If you do replace make sure you do not use cheap aftermarket ones -they do not work on the RR - stick to Bosch - same with MAF.
The RR is a 2000 model with 150k kilometres on it. I do not know if the O2 sensors have ever been changed. I will use the Bosch components for any replacements - though they are quite expensive here AU$327 per sensor! and the MAF from Barbagallo's is AU$595!
On Monday I get to try the RR with another MAF this will at least confirm the MAF as a problem or not. At the moment though I expect it will be the major problem with the RR.
 

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I swear I read that post last night but couldn't find if it was Gems or Thor.... :doh:
 

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The only reason I asked about other lines was to know if these were extra parameters you were recording at the time - just thinking along lines of whether recording too many could be slowing things down so chunks of data weren't seen due to slow refresh rate of data. Although when there is less activity in O2 there seems to be a little more in the other lines.

The speed of your computer has nothing to do with the ability to catch all the data changes. It is the speed of the vehicles electronics that causes this. It can only transmit so much data at a time through the OBD port which works at a much slower baud rate(think that is the technical term) than the laptop can handle. I know if I monitor my O2 sensors and rpm and MAF the O2 graph can show flat areas, but if monitored 1 at a time the graph looks perfect . With regards the RCL I don't know, but would suspect that it doesn't receive data any faster - maybe you could ask this question on the BBS forum - or in the diagnotistic section of this forum.
AUS$ 327 - wow that's steep. I paid about £55 (about AUS$95 I think) each for genuine from my local main stealer. Could you not buy in UK and import - same with MAF if needed?
 

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Discussion Starter #7
Hi

AMcK said:
The only reason I asked about other lines was to know if these were extra parameters you were recording at the time - just thinking along lines of whether recording too many could be slowing things down so chunks of data weren't seen due to slow refresh rate of data. Although when there is less activity in O2 there seems to be a little more in the other lines.
AFAIK the RCL does not provide the ability to monitor (in this case capture) data from "selected" sensors. I believe it monitors all of the sensors by groups, as per these choices...

[attachment=1:21knxnv1]Motronic Input Options.png[/attachment:21knxnv1]

The speed of your computer has nothing to do with the ability to catch all the data changes.
That's not necessarily quite correct as it can depend on what the computer is doing at the time. In the case of the RCL, the software is updating the screen display of data for the sensor "group"chosen and on occasion Windows can go off and do things *windows* wants to do :) I think you are correct about the OBD baud rate though the computer should be able to handle the OBD stuff quite easily. Each line of data for this capture file is approx 160 characters so that should not present a capture problem.

Just for completeness and perhaps for others interested, here is the O2 sensor image with a legend. The data values in the legend are NOT the values at that point in the graph, I copied the info from a captured image and placed the info here for descriptive purposes only.

[attachment=0:21knxnv1]o2sens legend.png[/attachment:21knxnv1]

The Lambda A and B sensors overlap so it looks like just the B sensor.

BTW what IS the lambda sensor? I thought the O2 sensor reading was referred to as a lambda reading. I read on the net about O2 sensors and that seemed to infer the O2 reading was a lambda reading?

The graph I have shown is not captured by the RCL. The RCL captured the sensor data only, the graph has been created via excel.

AUS$ 327 - wow that's steep. I paid about £55 (about AUS$95 I think) each for genuine from my local main stealer. Could you not buy in UK and import - same with MAF if needed?
That may be a viable option. Could you provide a suggested company and maybe a contact email address?

Thank you for the feedback...
 

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Lambada sensor and O2 sensor.....The same thing. In the UK we call them Lambada sensors, so thats what Land Rover call them, in the USA and other markets they call them O2 sensors, hope this helps. :D
SID.
 

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Discussion Starter #9
Hi Sid

SID said:
Lambada sensor and O2 sensor.....The same thing. In the UK we call them Lambada sensors, so thats what Land Rover call them, in the USA and other markets they call them O2 sensors, hope this helps. :D SID.
Sort of, that's more or less what I thought. The RCL shows lambda readings AND O2 readings, see here...
[attachment=0:1n2r89zh]lambda.png[/attachment:1n2r89zh]
So this is a little confusing.
 

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I can export the parts if you need them. You can pay by credit card and I can ship out within 48 hours on these sorts of parts.
 

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Discussion Starter #11
Hi

Rich998a said:
I can export the parts if you need them. You can pay by credit card and I can ship out within 48 hours on these sorts of parts.
Ok I may be interested. Will contact again via pm. Thank you
 

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IIRC the Lambda signal is the O2 signal "averaged/calculated" over time. The O2 signal is just a real time analog signal.
 
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