davew wrote:
Looking forward to seeing the pictures..
Pics are there, you just need to click on the links.
p73990: Still not sure why smoke is not coming out the tail... !
Have you tried pressure tests on the pots since the plugs look better now (ie. except for one) ?
Again any slight leaks could certainly be temperature-related yes
No smoke out the tail because there is no cyl with both valves open. This makes it easier anyway since i can then generate some pressure to force smoke out. Bumping over the engine is not an easy option since since i would have to do it directly from the starter. It has the self start on it. Besides if i want to test the exhaust its easy enough to plug them while running
I have no idea what you mean by "pots" If you are referring to a compression test then no, I cant see compression being a problem since there is no oil in the pcv and it runs way to smooth.
Since all eight injectors are very close together in pulse length as per my data logging. Im pretty sure that a loss of compression would create a rich condition. Which is not what the plugs are telling me.
Uploaded another graph of the maf sensor
(https://drive.google.com/file/d/1t78IKUXwN8AxDLMv42ZNQWYf3i9jCNrW/view?usp=share_link)
You've twice mentioned the fault being ambient temperature related, no faults seem to occur when the weather is warmer.
What readings are you seeing for intake air temperature and do they agree with actual air temperature?
Really IAT shouldn't make much difference because MAF sensors are self compensating for intake air temperature. Yet all MAFs have built-in IAT's...
p73990: I asked about you performing comparative 'pot' compression tests before I saw your plug photos - as you had mentioned one was different, but from all the pics they actually all look OK to me ! .... but whatever is throwing up that MIL is obviously only slight/intermittent so may not even be particularly visible/obvious like that anyway (?) There remains an imbalance/anomaly somewhere but -at least for me- it is seems inherently more electrical than anything else (?)
Again, from your smoke test you appear to have eliminated leaks on the intake side to your satisfaction. There could be a leak somewhere on the exhaust side of course but you would definitely hear that..... which brings us back to those O2 sensors themselves - again.
However from your data logging there is relatively good correlation between O2s across both banks; However earlier you mentioned when 'scoped their outputs were 'different', eg. 'one more saw tooth than the other' (and 0.5 volt different in level too) ? That may need some further investigation... ? (ie. It's well worth checking/'scoping these outputs/levels again when relatively cold and then again when relatively hot !) HTH
The intake air temp does generally follow the ambient. This truck has an IAT sensor in the manifold and because of the supercharger it tends to read higher depending on how well the intercoolers can cool. When it is cold it is usually very close to abmbient. I was looking to see if the maf can be read but havent found that yet.
davew
There are 2 sets of pic from the plugs the first set cyl 1,3,5 look slightly on the lean side. You can see quite a difference in the second set of pics. Between those pics i have done nothing to the truck other than 3 cans of fuel injector cleaner. An obviously we have spring temps instead of winter.
but whatever is throwing up that MIL is obviously only slight/intermittent so may not even be particularly visible/obvious like that anyway (?) There remains an imbalance/anomaly somewhere but -at least for me- it is seems inherently more electrical than anything else (?)
I agree. There is something at the tipping point of failure. Its just does not want to fail and the ecu is able to still keep things within the specifications.
when the temps are warmish. So at this point i need to eliminate all mechanical elements and get an idea how this system works and should look. In fall when it gets colder i have a pic to compare too.
The only thing left before going down the electrical road, is to check out the fuel system. Since the pressures seem to be OK, That leaves only the flow. It is possible to have pressure without sufficient flow, which would create a lean code. And as seen in the first plugs reference pic, not all the cyl on the same bank are lean.
I assume that the ecu uses #1 cyl for ign and injection timing. And since #1 cyl is one of the affected ones. I wonder if this is a result of min pressure, low flow and/or slow response time. This would also get worse in colder temps since the fuel becomes denser and harder to move.
(https://drive.google.com/file/d/16md9xZX8RSnbZ-ZMjBr4QX37JwufLOtg/view?usp=sharing)
Here you can see how bank1 is slightly more aggressive on lambda and O2 equivalence than on Bank2
(https://drive.google.com/file/d/1zhrqGf6ShIoYejgzuh0371MPJlkw1sDA/view?usp=share_link)
Here you can see how the bank1 sensor does not match bank 2 sensor readings. I mistakenly thought they were reading volts. Im not sure what "s" means. (secconds???)
Ah, now I see what you what by 'saw tooth' etc - as I had (reasonably but incorrectly) assumed you were monitoring (and comparing) the outputs from both O2 sensors with a dual-trace oscilloscope........... but you meant on your Analyser....
Ok, either way there certainly is an issue with the Bank 2 output - Bank 1 is just as expected of course....
As you have realised 's' is not volts, it must be some kind of 'stoichametric ratio' indicator - or a reciprocal of it -what does the Analyser Handbook state ? (Volts will vary between about 0.2 and 0.8 of course)
Not quite sure why the Analyser refers to the sensor heater on those traces either......
The other odd thing is that if the Bank 2 sensor output is 'yo-yoing' wildly like that if should shows itself as a 'hard' MIL ?!
Yea Im not entirely sure what im looking at. The other weird thing about this is that bank 1 is actually the problem bank and the one associated with the MIL code.
Some of the pattern may have to do with the data rate on my scan tool/analyzer. .
I still think this comes down to a fuel delivery issue since it does not affect all the cyl on one bank
Still thinking about some ideas to test this theory.
Well I was bemused about that too, as I would expect a persistent P1074 based on that Bank 2 waveform for sure but there still might be something else affecting Bank 1.... When I find (persistent !) disparities like that I tend to swap components around.. but O2 sensors are a pain to do that with (as they refuse to 'co-operate'...). Could also be a sticky injector though yes.... and they co-operate with removal/swapping better than O2 sensors ?! Might be a sticky/sticking injector but best to clean them off the engine of course, depends on just what your 'injector cleaning fluid' actually was ?
I'll say again - Supercharged Rangerovers have wide band pre-cat lambda sensors fitted. With wide band sensors voltage readings are meaningless in themselves. The only way to read mixture from a wide band probe wired to a vehicle ECU is by using OBD live data to read the equivalence ratio. ***
Lambda probes including wide band sensors need to be hot to work properly. Heater circuit readings just tell you about the heating of the probe, there's little useful info about actual mixture from heater sensor duty cycle / voltage / etc readings.
Just because you usually get an error code for mixture on one (either) cylinder bank doesn't mean that the other cylinder bank isn't also sailing very close to the wind in terms of having correct mixture (or fuel trims reaching an extreme) and if fuel trims are similar on both cylinder banks over a wide range of conditions the other bank probably is close to also flagging an error code.
I haven't yet looked at the video but I had no need to see the video to say the above. I will watch the video and see if I can offer any insight after watching it.
*** A good way to understand wide band probes is to think of them as a narrow band probe but with a built in air-pump that blows atmospheric air close to the narrow band sensor. The more air that is blown past the sensor at any given mixture the lower the voltage reading from the narrow band sensor will be. So the voltage reading in itself from the narrow band probe gives very little information about actual mixture unless you also know how hard the pump is blowing. You can only have one control/reading system connected to the wide band probe at any one time because the system has to simultaneously read the voltage from the sensor whilst controlling the pump, only with both sets of information (sensor voltage and air pump control) can the system know the actual mixture... It would be no good having one control unit read the sensor voltage while another unit controls the pump. If mixture strays far from anticipated mixture it can take a short while for a wide band lambda sensor control system to 'home in' on correct mixture, in fact even at close to stochiometric ratios they can take longer to reflect a true mixture reading than a narrow band probe because it takes time for the control system to do it's calculations and effect pump output. Because it blows air close to the sensor a wide band probe can accurately read much richer mixtures than a narrow band probe but they're not much better than narrow band probes at accurately reading lean mixtures.
Injector cleaning fluid used was Seafoam added to the fuel tank at the highest recommended strength
Swapping parts has crossed my mind but O2 sensors are particularly tricky. Quite often they fail simply by removing them. And im not at all convinced the O2 sensors have anything to do with this. They appear to be doing their job and compensating for something. Besides when they fail they are supposed to set a MIL. I did some more logging today on the fuel pump pressures and fuel trims. The long term fuel trims are near the top end of what I understand is acceptable, 16%for bank 1 and 13% for bank 2 at 110 kmh cruise. With bank1 compensating slightly more than bank2 on deceleration and acceleration. I will upload some more data pics.
In all the data logging I have done the only thing that really stands out (as I learn how to use this tool of course) is the both long term fuel trims. If both are higher than they should be with I suspect bank1 setting the MIL when it crosses the threshold, and bank2 not far behind. To me that seems to indicate fuel starvation but on both banks. Since the fuel enters the rail near the pressure sender at cyl 8 then crosses at the front of the engine to bank1 cyl 1 It makes sense that slightly low pressure/flow would cause bank1 to cross the threshold before bank2. And just to make things interesting, its sits just under the threshold until things get cold.
Am i making sense or is it beginning to sound like im overthinking it and spewing gibberish?
Lpgc
Bear with me I am old enough to remember carburetors, points ignition and days long before electronic fuel injection. Fuel injection is still a new learning curve for me. I only have 2 options, learn new technology or take it in to Land Rover and hand over my first born male child, The latter of which does not appeal to me.
I have only uploaded pics of data snippets. Equivalence ratios are included. Some of the data I am looking at may not be relevant since I have about 6 different ways to read information from O2 sensors. Im not entirely sure what data I am looking at yet. Also I am old and my eyes are not as good as they used to be. Sometimes i have to look at it 3 times to realize what I am looking at on these tiny cell phone screens. ( And as with most of us, I can shoot my mouth off before fully understanding it). At this point I am certain this is not a vacuum leak and fairy certain it is not a sensor issue. The equivalence ratios are very close to the commanded ratio. Fuel pump pressure (to me since I have no reference) appears to be slightly weak but reasonable. The fuel trims seem high to me albeit Im not entirely sure what is considered normal. I am trying to follow the general procedures for this code. Vacuum leaks test first. Passed. Check sensors and look for anomalies. So far so good.
Other than fuel trims all seems to be fine. I have put some data up for viewing. If you would like me to look at something specific, If it is within my means I would be happy to try to obtain it for evaluation.
I do believe It is sailing close to the wind on both banks, at this point I am mostly data logging to build a picture of it should look like. So that when the MIL shows up I have somewhat of a baseline. And I can then figure out where to look further without driving myself into the poor house by just throwing parts at it.
As i understand it, the O2/ lambda controls/adjusts fuel trims until the fuel trims exceed their working window. Which then sets in my case a lean MIL.
Things that affect the lambda. Vacuum leaks, bad O2 sensor (which should set another/different MIL) and fuel delivery.
Have I understood this correctly? If not please correct me
p73990: No not 'spewing gibberish' but your Analyser might be... and/or some 'odd' traces now for fuel pump/supply - if the pressure is low (intermittently) then that could help explain matters - particularly if one Bank is perhaps more affected/afflicted than the other...?
Trims were already showing quite good Bank/Bank correlation on the previous screenshots but not surprising as the problem is transient.
{Incidentally sorry but 'not co-operating' (eg. in the context of O2 sensor swapping) is just English slang for a Total PITA...!}
I wondered about that. At least i have some sort of data to look back at when this fault finally shows up again. Which im pretty sure it will..
FYI
So just for sh#ts and giggles, (Canadian slang for -- because I can) I decided to test if my EVAP system is operating correctly. I loosened my fuel cap after driving. It took 3 starts to set, but it did set an evap MIL. It even stated on the dash to check my fuel cap and that i had a large evap leak.
So that eliminates another possibility of a vacuum leak in that system