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2006-2009 Range Rover Sport
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Discussion Starter #1
System too lean,
--Short Term Fuel Trim 1 is 0.0
--Long Term Fuel Trim 1 is 15.62
--Short Term Fuel Trim 2 is -.78
--Long TermFuel Trim 2 is 18.75

Im pretty sure those numbers aren't right and I'm using way too much fuel. I had it smoke tested and the shop told me I had a vacuum leak in my EVAP leak detection pump. The smoke was coming out from around the driver side fender near the firewall. Can anyone confirm thats where the pump is, if not do you know something that would leak in that area causing my system to run lean?

PS: already replaced the MAF sensor and cleaned throttle body.
 

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2013-2015 Range Rover Sport
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480 Posts
. . . and your truck is a . . . ?
 

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2006-2009 Range Rover Sport
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Discussion Starter #3
Sorry, Its a 2008 Range Rover 4.2 L supercharged.
 

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Now add that to your signature as noted in the guidelines. Also add a REAL location to your profile for purposes of market differences.
 

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Discussion Starter #5
Sorry about that, I made the necessary changes and if theres anything I missed let me know!

Very respectfully,
Austin
 

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2013-2015 Range Rover Sport
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On my 08 RRS/SC, I found a routine of adding a fuel system cleaner (BG44K is the best I have found, Gumout's SeaFoam look-alike, next best), seemed to fix infrequent fuel trim issues. On my 08, I was using a OBDII reader that wouldn't read fuel trims, just set and reset codes - P0172 such; but a cleaning always worked. Moving to a 2001 Jag (revisiting an old friend); I upgraded codes readers and could now see the trims: began manually cleaning MAF sensors and throttle plates and bores and checking vacuum leaks since 4.0 AJ engines were susceptible. These worked, but I still continued regular use of fuel system cleaners.

It would be interesting to see what the short term trims are a higher idle (2000 rpm); not clear on how near perfect short terms become really poor long term; points to some vacuum leak at higher rpm, I think.

A leak in the intake manifold, or oil dipstick, or along the air hoses from the the air filter are likely sources of leaks . .

Maybe some pros will weigh in . . . .
 

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2006-2009 Range Rover Sport
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Not sure what NAS stands for but this is what my manual says for an evap pump---

DIAGNOSTIC MONITORING OF TANK LEAKAGE (DMTL) - NAS ONLY
The DMTL system is a legislative requirement for NAS vehicles. The DMTL system periodically checks the EVAP system and the
fuel tank for leaks when the ignition is switched off.
The DMTL system comprises the previously described components of the EVAP system with the following additional components; a
DMTL pump and a DMTL filter.
The DMTL pump is connected to the atmospheric vent of the charcoal canister and incorporates a Positive Temperature
Co-efficient (PTC) heating element, a normally open valve and a reference orifice. The DMTL pump is only operated when the
ignition is switched off and is controlled by the ECM. The ECM also monitors the electric air pump operation and the normally open
valve for faults.
The DMTL filter protects the pump from dust being drawn into the system when the pump is being operated. The filter is located
on the fuel filler pipe and is connected to the DMTL pump by a hose.
DMTL Operation
To check the fuel tank and the EVAP system for leaks, the ECM operates the DMTL pump and monitors the current draw. Initially,
the ECM establishes a reference current by pumping air through the reference orifice and back to atmosphere. Once the reference
current is determined, the ECM closes the normally open valve which seals the EVAP system. The purge valve remains
de-energized and is therefore closed. The output from the air pump is diverted from the reference orifice and into the EVAP
system.
When the normally open valve is closed, the load on the air pump falls to zero. Providing there are no leaks, the air pump will
begin to pressurise the EVAP system and the load and current draw in the pump increases. By monitoring the rate and level of the
current increase, the ECM can determine if there is a leak in the EVAP system.
During normal vehicle operation, the ECM energizes the heating element in the pump to prevent condensation formation and
possible incorrect current readings.
Leaks are classified as:
Minor - equivalent to a hole diameter of 0.5 to 1.0 mm (0.02 to 0.04 in)
Major - equivalent to hole diameter of 1.0 mm (0.04 in) or greater.
The ECM performs a check for major leaks each time the ignition is switched off, providing the following conditions are met:
The vehicle speed is zero
The engine speed is zero
The pressure altitude (70 kPa (10.15 lbf/in2) derived from engine load calculations) is below 3047 m (10000 feet)
The ambient temperature is between 0 and 40°C (32 and 104°F)
The charcoal canister load factor is 2 or less (where the load factor is a measure, between -1 and +30, of the fuel vapor
stored in the charcoal canister. Where -1 is 0% fuel vapor, 0 is stoichiometric fuel vapor level and +30 is 100% saturated
with fuel vapor.
The fuel tank level is valid and between 15 and 85% of nominal capacity
The engine running time during the previous cycle was more than 10 minutes
The battery voltage is between 10 and 15 volts
The last engine off time was more than 180 minutes
No errors are detected with the EVAP components, the ambient air temperature and the fuel level
High range must be selected on the transfer box.
• NOTE: A leak test can be performed using T4. This overrides the above conditions and is useful for checking correct system and
component operation.
The ECM performs a check for minor leaks after every 2nd major leak check or after refuelling is detected.
When the leak check is complete, the ECM stops the DMTL pump and opens (de-energizes) the normally open valve.
If the fuel filler cap is opened or refuelling is detected during the leak check, by a sudden drop in the current draw or a rise in the
fuel level, the ECM aborts the leak check.
If a leak is detected during the check, the ECM stores an appropriate fault code in its memory. If a leak is detected on two
consecutive checks, the ECM illuminates the Malfunction Indicator Lamp (MIL) in the instrument cluster on the next drive cycle.
The duration of a leak check can be between 60 and 600 seconds depending on the results and fuel tank level
 

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2013-2015 Range Rover Sport
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So unmetered air leak impacting both banks: calls for a leak test. Sounds like your guy did a good job in diagnostics.

Both session one and two of Arby's YouTube were outstanding. Wish I had seen this years ago. Thanks Arby.

NAS -- I guess -- is normally aspirated (i.e., not supercharged); we all had SC cars. But the discussion is much the same.
 

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2006-2009 Range Rover Sport
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Discussion Starter #10
Another thought; I get PO174, PO172, and PO171 which are too lean and too rich errors. Could this possibly point to bad O2 sensors?
 

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2013-2015 Range Rover Sport
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Sounds like dirty injectors to me. Spitting instead of spraying.

Did you get your leak fixed?
 

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2006-2009 Range Rover Sport
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Discussion Starter #12
Not yet, I haven't yet found where the leak is coming from besides the general location. I did however get a bottle of BG44k to put through the system.
 

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2006-2009 Range Rover Sport
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Discussion Starter #13
Just an update. I took it in and they updated a bulletin and upgraded the PCM/TCM, they said if the check engine light came on then to replace the spark plugs.
 
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