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Discussion Starter #1
I just bought a 2007 RR sport and my fuel light is on with 3/4 tank left. The vehicle states that it prefers premium fuel. However, being an engineer and knowing all about pre-combustion on high compression engines,e tc., i know that unless an engine states 'must be premium' you can operate regular fuel fine.

Has anyone had this issue/have suggestions? I have tried turning on and off the vehicle to see if it would reset but it has not.
I fear it may be related to lower octane/fuel pump or somehting more serious.
Thank you.
 

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Maybe you don't know all about pre-combustion. "Back in the day" when cars had hand throttles, and spark advance levers on the steering column, you found out that if you ran with the spark retarded, the engine traded output power for heat at the normal RPM range. If you ran with the spark too advanced under low rpm load, you ran the chance of melting your pistons. In the 50's we got centrifugally and vacuum advanced distributors to reduce human error. But advance curved were tailored to specific octane ratings. The higher the octane the slower the fuel burned, the slower the flame front moved and therefore the more advance the ignition could be. You would dare run your GTO on low octane fuel. Of course it only cost $0.35 per gallon.
The auto boys in the 80's decided that with the multitude of fuel grades, one way to insure that engines could run on whatever fuel used, was to install a knock sensor. If the fuel grade was too low and started the flame front too early in the cylinder, it could be reduced by starting the spark later (retarding). This is because spark timing is now done electronically not mechanically. However, there is a price to be paid. With lower octane fuel, the injectors still inject the same amount of fuel, but the ignition starts too late to burn it all,(knock sensor retards the spark) millage and power suffer and the engine runs hotter. Still this is better than having the flame front run into the top of the piston before it reaches top dead center. That generates tremendous heat in the cylinder which melts pits into the piston and eventually through the piston.
Long story short, with knock sensors, using lower grade fuel means reduced power and millage and everything runs hotter especially the cats.
I doubt that this has anything to do with the fuel light.
 

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2006-2009 Range Rover Sport
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Agreed not caused by fuel grade. You can run the RRS on regular, while not recommended, your car will be OK.

Are you still under warranty w your '07? Is the light steady on or blinking?

Few thoughts from cheapest to most expensive:
1. Have your mechanic check the contacts and clean them on the fuel sending/level gauge coming out of the tank.
2. Gas cap problem, ie not fitting correctly, but usually CEL light would be on as well.
3. Evap/charcoal canister needs to be replaced
4. Bad level sender in tank and needs replacement
5. Instrument cluster problem (if it is this and you are no longer under warranty, I would suggest the black electrical tape solution)

Or if you're Umberto, you really are low on gas. :D
 

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gooseyloosey said:
Or if you're Umberto, you really are low on gas. :D
:lol: ROFLMAO!!

err I mean, :snooty: now that wasn't nice...
 

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2006-2009 Range Rover Sport
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shanerange said:
I just bought a 2007 RR sport and my fuel light is on with 3/4 tank left.
So the needle on the fuel gage indicates you have 3/4 of a tank but the low fuel lamp is on? It's got to be some sort of malfunction in the instrument cluster pack software... I ran out of gas a few times before - as my dear, dear friend goosey points out - so I was interested in finding out how the cluster calculates and displays how much gas is left in the tank. This is the description of the fuel gage system operation, straight off the service manual:

Fuel Level Gage

The fuel level gage displays the fuel tank contents. When the ignition is off, the pointer returns to the empty position.

The instrument pack is connected to two tank level sensors. One sensor is located at the front of the fuel tank and the other is located at the rear. Each sensor uses a float operated MAgnetic Passive Position Sensor (MAPPS) for measuring the fuel tank contents. For additional information, refer to Fuel Tank and Lines (310-01A Fuel Tank and Lines - 4.2L)
For additional information, refer to Fuel Tank and Lines (310-01B Fuel Tank and Lines - 4.4L)

Each sensor is supplied with a reference current from the instrument cluster. The instrument cluster measures the returned output from each sensor which is proportional to the amount of fuel in the tank and the position of the float arm. The inclination of the vehicle, derived from a CAN message from the Electronic Park Brake (EPB) module, is also used to calculate the fuel tank contents. The instrument cluster uses the fuel level sensor signals and the EPB module inclination signals to accurately calculate the volume of fuel in the tank and display this on the fuel level gage. The instrument cluster monitors the signals and updates the fuel level gage pointer position at approximately 20 second intervals. This prevents the pointer moving continually due to fuel movement in the tank due to cornering or braking. When the ignition is off, the pointer needle returns to the empty position.

A warning lamp is incorporated into the fuel level gage and illuminates when the fuel tank volume is at or below 12.5 liters (2.75 Gallons) on petrol models and 14 liters (3.69 Gallons) on diesel models. This is accompanied by a chime from the instrument cluster and a message alert the driver to the low fuel condition.

The fuel tank content is converted into a CAN signal by the instrument cluster and transmitted on the CAN. This is received by Fuel Fired Booster Heater (FFBH) control module (if fitted) to suspend operation of the FFBH on diesel variants when the fuel tank content reaches 14 liters or less.

The following table shows the fuel tank fuel quantity and the respective pointer positions.

Fuel Tank Quantity (Liters) Needle Pointer Position
4.91 Empty
12.5 Low fuel (low fuel lamp illuminated - Petrol engines)
14 Low fuel (low fuel lamp illuminated - Diesel engine)
25.6 Quarter full
45.8 Half full
67 Three quarter full
81.05 Full
 

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Discussion Starter #6
After looking at the light. the actual location of the light is right above the gas gauge, but maybe it is a tire infaltion light as it looks like the shape of a tire. I could have sworn i did run low once on fuel and that same light was the low fuel level light.

Thanks for all the info related to combustion.etc. Hwoever, is it a low tire pressure light that is located right above the gas meter?

I will snap a digital pic if necessary.

thanks
 

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2006-2009 Range Rover Sport
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Kinda like this?



That's the Tire Pressure Monitoring System warning light. Normally, when that amber icon illuminates there is an accompanying message appearing in the message center below (look for an "i" icon while you are driving) to identify the problem, like a TPMS fault, a tire low on air, etc. The low fuel LED is on the bottom of the fuel gage.
 

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2006-2009 Range Rover Sport
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When I squint and look at that symbol, it looks like...

Hey, I may make that my new avatar.
 

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gooseyloosey said:
When I squint and look at that symbol, it looks like...

Hey, I may make that my new avatar.
Goosey, I know I just bagged on the joking around a bit... but that was seriously one of the funniest things I've seen! I wonder if anyone else has noticed that.
 

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gooseyloosey said:
When I squint and look at that symbol, it looks like...

Hey, I may make that my new avatar.
Took me a second. :lol: If this is the case, shanerange needs to sport it.
 

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2006-2009 Range Rover Sport
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Ok 3E, good point.

Shanerange, as a welcome to the board gesture, you get first dibs.

Looks like its back to Rastamonkey for me.
 

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Discussion Starter #15
it was actually the tire light and not the fuel. Unfott. and hopefully the tire pressure sensor system on the range wont be like the M5 i just let go of. A change in outdoor temperature of 20 degrees caused my tire pressure to fluctuate slightly and would constantly set these off. I just inflated my tires up from 33psi to around 38, but light is still on. i gues i need to be around 42?
 

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2006-2009 Range Rover Sport
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Rear tires should be 42, front ones 38 (cold PSI.) Also, the warning light may not extinguish right away, you may need to roll around a bit before the module reads the new pressure from the sensors in each wheel.
 

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shanerange said:
it was actually the tire light and not the fuel. Unfott. and hopefully the tire pressure sensor system on the range wont be like the M5 i just let go of. A change in outdoor temperature of 20 degrees caused my tire pressure to fluctuate slightly and would constantly set these off. I just inflated my tires up from 33psi to around 38, but light is still on. i gues i need to be around 42?
So when ever the tank got to 1/4 left the light would come on?
You would think that the light would stay on even when you filled the tank......no?
 
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