My Fuel Tank is empty when the car displays a quarter of a tank / 100 Mile range on the fuel Gauge .

I have a full bolt on upgrade on my 996 TT including;


650 cc injectors
Exhaust Catless
GT2 Rs Intercoolers
Additional fuel pump
Plenum and Throttle body
16/26 turbos - 1.3 BAR
Tune-OE MAF being used

Engine is not built. (Engine has been replaced for new with gearbox)


Whenever I get down to quarter of a tank of fuel or 100 mile range remaining the car starts to splutter as its out of fuel. It's been back to my Tuner 3 times trying to fix and they can't work it out

Can anyone help please ? Markski? Any other experienced Tuners?

If anyone can help me I'll be happy to donate £100 to their Charity of choice.

Thanks in advance

Si

 

Not a tuner, but IIRC THE issue is that you changed injectors. Your tuner would need to alter the scaling in your fuel parameters to adjust MPG back to a correct level. Since the fuel level below half tank is an electronic guesstimate, I bet that's your issue.

There's a few other threads on here where it's discussed, and Tony @ EPL chimed in about it, I think.

 

If the fuel gauge drops below 1/4 tank for any period of time things act weird.

Fill up the tank and it should get back to normal.

 

Any links to these threads?

Any other suggestions?

 

If the battery was disconnected with the tank containing less than 19l of fuel, the calculated range on remaining fuel will be incorrect or lost.

If the tank contains less than 10l it possible the fuel level warning light will no longer be activated.

If the power supply is restored with the fuel level at less than 19l it is possible the fuel level display may display more fuel than is actually present.

Solution: Refill with at least 19L of fuel then the operating range and its display precision is guaranteed.

 

I would think that the fuel gauge would revert to empty, when below half a tank and battery was disconnected...just as a safety.

It's quite possible that the fuel level sensor arm is snagging on a hose or wire in the tank, since I assume the fuel pump was upgraded at the same time, and things didn't go back in as they should.

 

The fuel level switches to a fuel consumption calculation based on injector pulse width when below roughly half tank. With larger injectors your actual fuel consumption will be greater than the calculated consumption and you will run out of gas with the fuel gauge still indicating fuel on board. I'm not aware of any way to reprogram that.

 

My Tuner text me this morning assuring me they had changed the scaling in the DME for the injectors.

Could it be anything else?

 

What pwdrhound is saying is true, BUT, i have 1000cc injectors, and my fuel gauge works normally. It's just the "miles to empty" that is off. I tried it, with my tank less than half full, disconnecting battery and reconnecting, the gauge goes to full empty. Putting in a few litres to pass the halfway point makes the gauge go back up to where it should be.

 

Yes, it can and is usually done on a better tune. I'd be surprised if Kevin doesn't do this.

OK51, there is also a fuel gage calibration procedure that is done with PIWIS, not sure if Durametric has this function. IIRC, a completely empty tank is filled with 28L of fuel and the calibration performed. The calibration is normally never lost, but possibly with the flash...

 

Yes, exactly. But AFAIK it can be fixed in the tune, if the tuner wishes to incorporate those changes.

 

It should work as you describe, if your usage is pretty consistent throughout the tank. Just watch out for driving like a grandma from full to half tank, and then the Stig for the rest - you would probably run out of fuel while still showing on the gauge.

 

Unfortunately, I'm pretty consistently floored at all times, lool

 

There are a couple things to check:

Check if it's really empty. How much fuel can you fill up? If it's not what it should be, check your return line that goes into your fuel pump basket.

The tune: many tunes don't have a correct injector size compensation for the fuel consumption. This value is different to the injector size setting that is needed for injection time calculation. Have your tuner verify this setting. If he is brave, he tells you what this value is set to

You say you have a 2nd fuel pump. Probably inside your tank? When the fuel level sender unit was out, it could have been installed incorrectly (check rotation) and/or the floater might be bent.

Take it apart and check the floater. Take all fuel out and refill 28 liters of fuel and do a tank calibration (Porsche tester needed).

Andreas

 

this could be solved really quick.
if your tuner tunes he will have a durametric cable, take it to him and have him log the actual lambda on boost... if hes not local, buy a durametric cable for $287 before you blow it up... and Im really serious about it...
you also mentioned you changed pumps... well something could be wrong there too.
a datalog will show u if your running lean or not... wrong scaling would not cause sputters unless he really doesn't know what to do...he also has to add fuel not just scale for the injector...
stay off of it until you figure it out...
not sure you even added another pump... show me pics, how and what was done