LR3 2006 4.4ltr, fuel issues which Land Rover cannot diagnose

shedlock2000

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Sorry for the long post which follows, but I think you need all this information to help out! I am having a protracted issue with my LR3, 2006, 4.4ltr, LHD, HSE, 120,000miles. She unfortunately became wet in a recent flood event in my town and drew in water through the fuel filler cap (The car was running and being loaded to exit the site when the bank side slipped away. The insurance won't cover any issues and I am a (now) very broke student). The inside of the vehicle remained largely dry, but she was running until she stalled from water in the fuel.

The water contained a soft fine clay particulate which clogged up the fuel pump went though the filter and into the engine. The injectors were clogged but have been replaced. The fuel tank, pump, filler cap, and evap. lines have been changed with spares from a running 2006 (fitted with a recall tank upgrade -- a straight fit, 2010 tank and pump). The battery box has had no water ingress, and I have removed the transfer case module and ECM to inspect for water ingress in the plugs or module (which there was not). The E-box fan shows as 'off' in the code reader, but a false feed runs up the fan fine. The fan fuse is good.

The problems are these:
  • After an hour or more of driving, or about 20 minutes of idling in hot weather, the vehicle begins to run progressively leaner and eventually stalls.
  • Switching off the key for 10 seconds resets the ECM and the vehicle runs fine for about 10-20 more minutes when the difficulties begin to slowly re-occur.
  • Switching off the vehicle for 10 more seconds will again re-set the problem for another 10-20 minutes.
  • The symptoms occur more quickly in the heat (especially the 35 degree heat we're having at the moment), but last night, with the ambient air at about 18 degrees, she idled for 2 hours without any difficulty then drove home perfectly.
  • Opening the bonnet reduces the time which the issue occurs -- however, she will still begin to fail eventually.
  • She seems to perform without issue much longer with a full tank of fuel -- though this may also be just a corollary, rather than a cause.

When the data streams are observed during the lean times, the short term fuel trims max out at 41.4%+ and the O2 sensors run to around 1.16mA (though Bank 1 is usually more extreme than bank 2 -- despite the fact that Bank 2 records more lean codes than bank 1). There are rarely any fault codes thrown -- even if the vehicle stalls, but occasionally a lean code for banks 1&2 are given, or (very rarely) a misfire code. When the vehicle is running normally, fuel trim figures hover around 2 or 3-4% and bounce around as you might expect, and the O2 sensors report 0.01mA and flick around properly. Sensors progress to the former slowly and progressively, and correlate with the progressive lack of power one expects from a shortage of fuel. The O2 sensors have been disconnected and codes reset then a test run has been made under which the vehicle failed again after about 10 minutes of idling and 25km of driving. From this I conclude that it cannot be O2 data which is being improperly managed by the ECM.


Work done has included:
  • -- Replaced O2 sensors and injectors,
  • -- Blown out fuel lines,
  • -- replaced pump and filter (and fuel tank).
  • -- Cats. inspected and found to be in excellent condition.
  • -- Battery box, Transfer case module, and ECM inspected for water damage.
  • -- Inlet manifold checked for leaks; the evap. system has been isolated from the engine to eliminate that.
  • -- Fuel tank cap has been removed to check for vacuum issues and replacement fitted.
  • -- Engine ECM has been re-mapped to avoid stored data glitches, vehicle taken to Land Rover (who have been unable to diagnose the fault but charged me $1000 for the privilege).
  • -- Inside of vehicle checked for water ingress and the passenger (LHD) carpets removed to dry and clean out wiring in the sill.
  • -- Battery voltage checked: good and consistent,
  • -- Fuel pump electrical-feed plugs under front wheelwell checked for water/dirt ingress.
  • -- Tank has been inspected for floating bags/plastic,
  • -- Fuel pump removed and bench tested,
  • -- O2 sensors disconnected for trial run,
  • -- Smoke test carried out,
  • -- E-box fan/fuse tested,
  • -- Fuel rail pressure checked (80psi)
No existing fault codes show; all historical codes have been eliminated and all systems operate normally. Vehicle ECM has been hard reset prior and after ECM hot-soak.

When the vehicle is just started or cold, it runs perfectly and without issue. However, very, very occasionally (only twice ever), there is some hesitation to start which feels like a lack of fuel too (the key cycle does not start the vehicle but there is a faint try to start. Starting the car is possible on the second cycle).


Further information:
The MAF and MAP sensors record appropriately and within parameters; the coolant temp. is about 95, and the control module temp. between 49-62C; fuel rail temp fluctuates around 50-60C.

Fuel pressure when running well is 80psi (over the 65psi required), but I have not yet run the pressure gauge while the vehicle has been running lean, as this at first only happened on long runs. The new O2 sensors seem to have contributed to a faster onset of symptoms.

When the vehicle begins to show symptoms, it first presents as a lack of power on hills or accelerating, a general hesitation and lack of responsiveness, and later as a miss; when the vehicle becomes severely affected, there is no acceleration and maintenance of speed is not possible, there is then a lot of coughing and bumbling and the vehicle cuts out. Switching off the key and waiting 10 seconds starts the car as normal and no symptoms present.

I am guessing that it is a temperature-related sensor fail, but I do not know what sensor could cause the difficulties as the sensors involved in fuel regulation have been checked or changed: the MAP and MAF report fine throughout, the O2 sensors have been replaced, and the temperature sensors report properly and accurately. Clearly the ECM is being reset and the learned data is being deleted by switching off the key, but what information is the ECM getting which causes this issue?



Any suggestions, people?
I have been advised to:
  • -- check the ECM fan (works fine, but is shown as 'off' by the code reader,
  • -- and to check the fuel pressure during the lean periods which requires the pressure gauge to be continually inline. This would only indicate a physical lack of fuel to the engine, not the reason for the lack of fuel (which, I am assuming would also be ECM?)
 

tlt

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Great description and write up... Question, when you pulled up the carpets had they been wet?

Unrelated to your specific issue, but did you also change the oil, engine, transfer box, transmission, and differentials?

I am guessing you have corrosion in the wiring harness or fuse boxes somewhere. There are a number of fairly typical Brit wiring connections in those runs in the cabin, and probably elsewhere..

You mention that it works better with a full tank of fuel. This kind of sounds related to the ventilation, and piping for EGR tubes, etc. When you dropped the tank, did you pull that assembly out and attempt to clean / purge all the lines? I assume you have also added dry gas, or other fuel system cleaner / dryer along the way.

Why won't insurance cover it at all?

Oh, and you are speaking in (Greek) Celsius, where are you located?
 
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shedlock2000

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Yes, all oils were changed afterwards.

Carpets were wet, but we're fully dried out afterwards. Non of the wiring harness which became wet was related to the ECM wiring and no other faults present. Also, no fault codes present. The grounds in the rocker covers were inspected and are good. The electrical plugs which feed the fuel system were also inspected and are clean and dry.

I had not considered an evap. issue but had blanked the evap off the engine to test for it without any success. All of the lines were blown out and cleaned prior to replacing the tank. I have also ordered a valve and canister just in case the gate related (though j don't think they are).

I performed s test run last night and was able to drive much further than previous nights with only a little bit of fuel in the tank. I believe this to be related to the external air temperature: the cooler the ambient air, the longer it takes for symptoms to present. This seems to indicate a temperature related fault - but possibly not an engine sensor (as they usually pick up engine block heat as soon as the engine reaches temperature). I'm fitting a new MAF later today (thinking inlet air temperature issues).

I'm located in Canada, but I'm from the UK. I'm trying to write clearly and precicely in language that those in the U.S., Australia, Britain, and in Canada, can understand! Which is actually harder than it sounds!
 

tlt

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LOL, you are doing a fine job, but be yourself.. I'm on disco3 as well.
 

LAarch05LR3

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Hello I'm here in Los Angeles and have a 2005 LR3 SE 4.4l 8cyc. And seem to be having the same issue that you so meticulously described. I was told by the local dealer it was the ignition coil switch heating up after a hefty fee they replaced it, and the problem persisted, so they then said i had a faulty alternator, there were voltage spikes, they said, so i replaced that, it still persists, i recently read online that it may be my brake light switch, so i replaced it, no change, i was told check MAF, cleaned it out, no change, someone said clean throttle body, done, no change...Lastly i took it to an independent mech. He said may be the crank shaft position sensor, haven't done it yet....i am at my wits end please help!
 

Donelle

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I have the same problem with my 2006 Land Rover LR3. Engine light came on. Reading P0171 fault code running lean on bank 1. The following has been completed:

1. Replaced MAF sensors
2. Replaced Air Filter
3. Replaced O2 sensors
4. Dealer tested for vacuum leaks. None found. Recommended Fuel Injectors to be cleaned and tested. Done after Spending $1000.
5. Replaced Crank Position Sensor

Only thing I can think of is to perform a fuel pressure test and replace fuel pump and filter.

Please help
Donelle
 

ozdo4212

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Check Intake manifold for condition and and replaced the gaskets that simple!
 

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