rangerovers.pub
The only place for a coil spring is up Zebedee's arse
Member
Joined:
Posts: 57

Actually the fuel pump doesnt look that bad. It does follow the fuel pump percentage line. This is also a PWM controlled pump, so the pressure will go up and down according to what the controller gives it. What does bother me is the amt of sawtooth in the pattern considering the smoothness of what i assume is either the PWM signal itself or the commanded signal to the control unit. Also the manual calls for 45 psi at idle, It might be averaging 45 psi but it falls to as low as 41psi. and not smooth.

Member
Joined:
Posts: 720

Indeed, a (relatively steady) pump sawtooth is fine but yes, just what is happening in the last third of that Analyser trace ?? 'Averages' are fine in general too but it is the/any transient anomalies that throw up those intermittent MILs !?

Member
Joined:
Posts: 1345

I've had a look at the 2 traces.

On both traces long term trims (Ltft's) are a little higher than what I'd expect but I dunno if the 14% would be high enough to cause an OBD code in itself. There's nothing to show engine load in the traces (the tool could be set to show RPM / throttle position / calculated load / etc). Were the driving conditions during the traces the same conditions that cause the codes? Also Ltft's by themselves don't indicate mixture or what the fuel system is doing to try to correct mixture, to see that info we need Ltft's, Stft's and lambda equivalence ratios all on the same trace. Stft's normally steer the Ltft's over time but Stft's reach either extreme (say +25% / -25%) the ECU can interpreted that as a potential error condition during which the Ltft's are not steered by Stft's. So, say you've got a Ltft of +10% and a Stft of + 4%, over time that would steer the Ltft to +14% and the Stft would be zero. But if you've got Ltft of +10% and Stft of +25% the Ltft will remain at +10% and eventually the ECU will generate an error code. It might be a good idea, if possible with your scan tool, to do some traces showing all of the fields I've mentioned here.

Fuel pressure also has command pressure but I don't remember if command pressure is a field you can read with a scan tool. I'd normally expect fuel pressure to rise during high engine load on-boost conditions. But if fuel pressure is close to within command pressure I wouldn't expect much of a problem (at least not .. You reckon it should be 45psi during the trace conditions but if so, and if it only falls to 41, I wouldn't expect that to cause much of a problem (at least not during low engine load conditions). Behind the scenes the ECU compensates fuelling for fuel pressure, I don't know if the ECU has a table for fuel pressure petrol injector pulse duration compensation or calculates the compensation but the amount of necessary compensation for lower or higher than expected fuel pressure is quite simple - compare the square root of expected command pressure (45 is 6.708) and the square root of actual (read) pressure (41 is 6.403) and there's only a 4.8% difference of what a petrol injector would flow for any given pulse length with the lower than intended pressure. Even if there were no petrol injector pulse duration compensation for fuel pressure, with expected pressure of 45 and actual of 41 we'd only expect to see a 4.8% change in fuel trims. But behind the scenes the ECU will add that 4.8% onto petrol injector pulse duration and in theory (because of this compensation) the lower fuel pressure should therefore not be reflected in fuel trims at all. Normally on these engines if there is a fuel pressure issue the ECU will come up with specific error codes pointing to the fuel pressure problem.

You've done smoke / plenum leak tests.
Done a couple of traces already,
I'd advise doing some more traces with the extra fields as mentioned above and in various driving conditions.
Maybe do a compression test.
If all seems good from the above I'd reset adapted values (fuel trims), start the car and immediately go for a drive with mixed driving conditions whilst monitoring Ltft's, Stft's and equivalence ratios (like I mentioned in an earlier post).
Still no joy I'd be looking at the Maf, maybe compare voltage readings at warm idle and under other easily comparable conditions (such as 60mph cruise on level road) with someone else who has the same model vehicle.
I still wouldn't rule out the evap system despite the tests you've already done.

Member
Joined:
Posts: 57

I will see what I can get. I am limited to max 8 traces at once and this does slow down the read rate but should still be good enough. On Sunday when i go to town I will get some varying conditions. Should I be monitoring this stuff when the engine is stone cold as well? I would think they would have allowed some extra fudge factor for cold conditions.
One more dumb question I see on other sites some discussion about ecu reprograming/updating. Is this something i should get done? If so dealer item i assume? It has about 230 000km on the clock.

Just a note. I still have not seen the lean code since i last noted it in this thread.

Member
Joined:
Posts: 57

Those heavy anomalies are going downhill while using cruise control. It does this when the throttle is closed until the speed is reduced to a certain point. (quite slow or until brakes/throttle applied). My interpretation of this, is that they want the fuel pump to have reserve pressure in case of full throttle application. This makes me believe it is a pressure command to the pump control unit. For that reason Im also in most cases trying to do all my data recording on the same stretch of road for comparison purposes while physically watching things at other times.

Member
Joined:
Posts: 1345

When you first start it from stone cold it'll be running 'open loop' mode ignoring all the equivalence ratios etc. But it'll switch to closed loop mode after maybe 30 seconds to a minute or so depending on how cold it (engine, weather) is, yes it would be a good idea to monitor readings during that time too.

If you can only monitor 8 fields go for rpm, load, ltftb1, ltftb2, stftb1, stftb2, equivalence ratio b1, fuel pressure.

It's fuel pressure on demand and fuel pressure does rise under high load conditions, there will always be some fuel pressure (even with engine off there should be some pressure retained in the system), pressure will probably be at around it's lowest during very low load and over-run conditions (downhill cruise on like you've said).

The same stretch of road / conditions compares like with like conditions but probably doesn't see a very wide range of conditions. The problem might not occur during some conditions. I'd test under the same conditions but also test under a wider range of conditions. For example you might be able to pull over and let it idle for a while beside that stretch of road, then set off and accelerate quickly putting the engine under boost loads.

Member
Joined:
Posts: 720

P73990: I was simply assuming running steadily on the flat .... with a warm engine; Too many (other) variables to complicate matters otherwise !

Member
Joined:
Posts: 57

I will try to remember to get those traces tomorrow evening on my way home. I was starting to think I should include rpm or load on some of these traces just for reference. 6 months from now they wont mean much to me if I cant remember what the conditions were.
I have a couple of dumb questions for to gain some more understanding
1 I have read on other posts where guys have said they changed some o2 sensors and that solved the problem. Claiming they were old and probably reacting slower than they should. Rate of response, I think was the term. Is this possible? ie reading lower and/or slower. I need a little more than someone's parts cannon to go down that rabbit hole.
2 Relating to question1 If I understand this right, disconnecting an o2 sensor should cause the ecu to go into some sort of safe mixture/map mode (open loop??? using cold mixture settings). Would this then be visible on the ignition timing, injector pulse width, fuel pressure, etc. traces for comparison. And also visibly on the plugs as a richer setting?

Member
Joined:
Posts: 57

So i read something about oiled kK&N air filters fouling MAF sensors. Since the air filter i just replaced was of this type. I cleaned the MAF with rubbing alcohol and went for a rip. Logged it from the end of my driveway. Engine was already up to min temp when i started logging. I goofed and logged both the equivalence ratios but missed fuel pressure.
File is a pdf, may give you a better look. Sometimes this works but not always. If this format is preferred let me know. Ignore anything left of 0, Im not sure why my tool does this.
(https://drive.google.com/file/d/1sfPyjiuMdKU2PkrXWmU0sauC6JpkwDGj/view?usp=sharing)

Member
Joined:
Posts: 1345

The format is good thanks. I have one browser tab open showing the definitions/scales, another tab open for scrolling sideways through the data (just looking at the top chart which shows all the fields).

Both traces (before cleaning the MAF and after) are very similar.

The long term trims are generally high positive but the short term trims are not far from zero. If we had a high positive trim at a certain engine load (when running closed loop) with a high positive short term trim and with equivalence ratio holding above 1 it would point to a lean problem at that engine load but we're not seeing that. The engine seems to be getting correct mixture during all closed loop conditions and mixture goes suitably rich during high load conditions (like it's supposed to).

Like I said early in one of my early posts on this thread, supercharged Rangerovers can throw a few codes for mixture if/after fuel trims have been reset (and you said you reset fuel trims?). If the code doesn't recur it could be that you've done enough drive cycles with various engine loads for fuel trims to have been relearned... No codes because mixture doesn't hang lean for long enough to produce an error code now because trims have been relearned.

If code(s) do recur I'd expect it would be because Ltft's (particularly bank1 Ltft) is quite high peaking at around 17%. If I remember correctly most SC RR's I've worked on have Ltft's of around 7%. There could be various reasons / faults causing consistently high Ltft's including under-reading Maf (yes they can be contaminated with oil / dust from air filters etc, or can just go bad with age and use). Can probably rule out a vacuum leak because trims are around the same at low engine loads (when there's most vacuum and a vacuum leak would be most revealing in terms of trims) as they are at higher engine loads (when a vacuum leak wouldn't make much difference), though that still doesn't disprove a none-vacuum false air leak (a leak in ducting between the Maf and throttle body), a leak there would see high trims across all engine loads. There could be a problem with the fuel pressure sensor, if that were to read above actual pressure the effects would be to both reduce petrol injector pulse lengths and cause the fuel pump system to deliver lower than normal fuel pressure. What fuel is in the tank (high ethanol content etc)? High ethanol content fuel has a different stochiometric ratio to normal petrol (it needs a different amount of air to burn the same weight of fuel) which can be reflected in fuel trims. But I think at this point I'd be wanting to try a new Maf on it.

Member
Joined:
Posts: 57

Lpgc
Here are the logs you suggested. I let it idle for about 5 min and then drove at different speeds with a few hills for good measure and without cruise.
(https://drive.google.com/file/d/1gGn3xlvCLwtCL9uyUvxO9MzXJwXfzEQN/view?usp=sharing)

I also did a maf log as well for interest.
(https://drive.google.com/file/d/1pqW-K7w2iJvczzIjGXKTnL55ou48j3JZ/view?usp=sharing)

Member
Joined:
Posts: 57

So I spent the day attempting to get to my fuel filter. And found a few interesting things. I must have gotten a good one not built on a Mon or Fri. My fuel filter had the manufactures seal still on the access holes on both sides. I also found that there are 2 wires on the bottom of the filter that when disconnected turn set the fuel gauge to empty. Both wires appear to be isolated from each other. I wonder if there is a switch in the filter that sets the gauge to empty if the filter becomes plugged.
I also found a date on my MAF sensor and it is the original made in Germany part with an 08 year on it.
pics of filters
(https://drive.google.com/file/d/1TXxgCue4pR6VzLQmewZq4vhQObIEQxL7/view?usp=sharing)
(https://drive.google.com/file/d/1-7LMmQKjOyW43gWkgqMW-r8PT-R4XQAy/view?usp=sharing)

Member
Joined:
Posts: 57

And to top it all off. I THINK WE HAVE SUCCESS.
I crawled under the truck to look at the O2 sensors. I found some crap welding on the pipe and the O2 bung that does not look original. It appears that someone has changed the upstream sensors since I can see wrench marks on them and either the bungs spun in the pipe (doubtful) or someone over heated the pipe with a torch and then attempted to weld the holes up. So I decided to take some pics for you guys. After some effort to get my phone in there to question this and get some pics for you, upon reviewing the pics I spotted the telltales of tiny pinholes in weld on each side that are hidden from view. And the bank1 side is slightly larger than bank 2
I have read that these pinholes can cause the P0171 and P0174 lean MILs.
Pic here.
Bank 1 (https://drive.google.com/file/d/1PcmpetTjJSRtsTDsOGYjZQY-tjkjzX3f/view?usp=sharing) A little black smile near the bottom of the weld just above the flange

Band 2 (https://drive.google.com/file/d/1Dhl-dsXqUyUJABrlr_yLFRpWX6j_ZITs/view?usp=sharing) I couldnt get the camera around the backside of the weld
This one is a little harder to see. There is a small black spot on the left of the weld right at the edge of the weld with the telltale puff heading away from the weld. and a small black spot above the weld where someone struck an arc while not being ale to see properly

Looks like i will be removing these for repair and/or replacement.
What are the odds of not destroying the O2 sensors during this process?

Member
Joined:
Posts: 720

p73990: Have to admit I assumed you had already (visually) checked out the O2 sensors - most notably their electrical connectors anyway.....
as that can often be the source of such intermittent faults.... That said pinholes like that often will produce MIL codes like that too, yes....

-Check with smoke and/or the proverbial/crude 'strip of tissue on a stick' to be sure (?)
Liberal/temporary application of high temp. silicone around those welds will prove it out (?)

Thus overall it might 'just' need better 'welds' than those to seal any pinholes up...( ie. rather than requiring any new Sensors ... )
but the Sensors maybe won't like the heat of welding too close of course: I would be inclined to grind those 'welds' down and re-do them properly...
(Not quite sure why those 'welds' are there anyway, carelessness removing the Sensors damaged both pipes ??)

(PS: <20% chance you will trash the sensors removing them (?)
Might be best to soak in freeing/penetrating oil for several days first though ?!)

Member
Joined:
Posts: 57

I did do a visual for exhaust leaks when I first got the truck. And they dont make enough noise to hear. When I saw the welds I did remember them. But the telltales are not visible except in the pics. Even the holes are not visible in the pics only the telltales. Getting the phone in there for you guys meant I got angles and detail that no one would never see. Im not sure the stick with tissue would show these. Looking at the fueling traces the trims only show and issue once the revs are up with engine load after is settles into cruise. There may not be enough leakage to show up at idle.
I hadnt thought of the silicone. Might work for a few days to test. Ultimately they will have to be removed for me to repair them properly. There is no way to get anything in there to work with. I can think of 2 reasons that someone has done this.
1 They blew holes the pipe with a torch while trying to heat the sensor bungs.
2 Blowing holes using the welder instead to try to locally heat the bungs
Either way It was an on the truck repair where the welder is blindly stuck in there with the hopes of hitting the right spot and not burning thru. Since you cant see anything around the welder Then you just keep building until the hole goes away, Since you cant see where you are welding you have no control of where and how much you are putting on. Works for a while but blows out a few years later.
Im guilty of this myself, but a pinhole made no difference years ago. I have some pin holes in my winter truck with dual wide band sensors and it doesnt care, I didnt even set a mil when the downstream sensor fell out.

Member
avatar
Joined:
Posts: 7927

Do you have anything like Gun Gum (https://www.holtsauto.com/holts/products/gun-gum-paste/) available in Canada? Grind or wire brush the loose stuff off the dodgy welds, then a dollop of paste would seal the holes. As long as you don't expect it to give any mechanical strength (as some do), it works really well.

Member
Joined:
Posts: 57

Yea, we have something similar. Most dont stick for more than a few months if not prepared properly. Biggest problem is that i can barely get my little hand in there let alone a tool. Wire wheel, grinder no chance of getting it in there. I will see what can do today. It will only be temporary but good enough to prove the issue.
I also have the option of putting more weld on it. Might get me thru to winter when I wont be driving it anyway.
Same as the previous person with lots of hope and good intentions. LOL
Unless I can figure out how to see thru my tools and body parts LOL

Member
Joined:
Posts: 720

p73990: You could definitely/probably use a jubilee clip (plus perhaps a small piece of ally on Bank 2) to keep the sealant/paste in place for a while whilst doing a longer test ? HT Silicone usually lasts longest as it is sticky, flexible and cures with heat - so you can build it up a little at a time, eg. with a hair drier ?

In fact I have 'bodged' (aka 'kludged' !) things up like that and they have lasted for years ...

Good to see they have 'thoughtfully' put the sensors on short pieces of pipe so you can 'easily' replace both at the same time, ie. pipe and sensor ??
Note that 'easily' is a relative term there of course !

Member
Joined:
Posts: 57

Easily? LOL They put these things together like an F1 car, except the forgot that it only takes 2 people about 5 min to remove the body to gain access. No special tools required.
I did notice that. Are these pipes available separately in the UK? I looked on lr parts direct and they are not shown separately. It appears they come with the manifold or the catalytic converter. Neither of which is anywhere close to an economical repair here. Matter of fact the cost of replacing the cats at dealer price exceeds what I originally paid for the truck.
I do have the ability to make new ones myself but getting the alignment right is particularly difficult due to warpage while welding. So I would prefer to just replace them.

Member
Joined:
Posts: 57

I think by jubilee clip you are referring to what we would call a hose/screw/gear clamp. But I have no idea what "ally" is.