Range recalculation

chrisH · Nov 30, 2008

I've got a 997 Gen II out on demo and after refuelling with 3 gallons the range, light and low fuel message doesn't change at all infact range continues to drop. Also there is a red "!" light on. I don't want to fill it up anymore as its a demo.
Does anyone know if this is all normal and if so when does it update itself to account for the fuel added?

Terry · Nov 30, 2008

Not sure about the Gen 2 997, but my 996 fuel guage did not register additional fuel being added unless the tank went to half full or above.

Terry

chrisH · Nov 30, 2008

The gauge not moving is one thing but surely the message "Consider refuelling" should go out and the range calculation doesn't change at all. So it has just ignored the +3 gallons added.

tscaptain · Nov 30, 2008

Chris, I had to put a couple of gallons of "Ultimate" in when my usual Shell garage was out of V-Power and the gauge, range and all increased as one would expect. Maybe the OPC has modded the software to get some more fuel out of you![

]. Are you trying the manual or PDK, btw, not that it's got anything to do with the thread!

chrisH · Nov 30, 2008

It's a PDK and I thought it was interesting with 7-speed box giving 75 at 2000 revs. Makes for good economy but responds instantly to throttle or paddles to downshift. Also like the touch screen, so much better than the old one. I wonder if you get the touch screen for radio and IPod/ USB etc if you don't choose the Sat/ Nav option?
Maybe there is a fault as there as RED "!" on the dash which I assumed was the low fuel warning. There was no handbook supplied with the car, so I am stuck and have to drive it back at 6AM tomorrw morning.
Does anyone have a GEN II handbook and does it way what the ! means?
How am I supposed to know what the real range is when I have just put 3 gallons in but it still reads the same range figure as beforehand!

tscaptain · Nov 30, 2008

I have the handbook! Firstly, there is a note which says "If the tank is nearly empty and you top up with only a small quantity of fuel, this cannot be registered by the level gauge and cannot be used to calculate the range on remaining fuel" Wouldn't have thought 3 gallons was a "small" quantity. Secondly, "with less than approx 10l the warning light for the level gauge lights up". This is orange and at the low end of the fuel gauge itself. Additionally, a warning is displayed on the on-board computer. It doesn't say anything about the red ! Nor in the section about warnings on the instrument panel and on-board computer does it say anything about a red ! for low fuel. I reckon you're good for at least 75 miles! The red ! is for faults, I believe, such as the dodgy main beam light I had recently and nothing to do with the fuel state. Although having said that I think the red ! comes on when you cancel an on-board computer message too. Hope that helps
Alan
Ps I have the PDK and love it!

chrisH · Nov 30, 2008

Alan,
That's a great relief to hear its normal. I agree, I assumed I have 75 mls worth left as that was the 3 gals I just added.
I wonder what happens when the range goes to zero, I hope it doesn't tell the engine to stop!
If I may say I think this is a serious misgiving in the design. What is the point in having a trip computer rnage that dosn repond to adding 3 gals?
I have had VW's with trip conputers since the 80s and they always show the effect of adding fuel, however small the quantity.
I never had this with my Boxster as I always filled it and have just traded mine in for a facelift so car less until March.
I will ask the OPC tomorrow if this is a feature on all models or just 911. It was earlier stated that 996s did the same.
Many thanks for letting me know as we have to go a funeral and cannot afford to run out.
Chris

Rodney Naghar · Nov 30, 2008

This has been discussed before and there is a technical article on it on the 996 forum, the same applies to the 997.

http://www.porscheclubgbforum.com/tm.asp?m=346360

"Below is an extract from a TSB regarding occasions of C4s running out of fuel, to which I've added a couple of notes of my own.

In all current models except the 911 Carrera 4 (996), the fuel level warning light (reserve) illuminates when there is approx. 10 litres of fuel remaining in the fuel tank. When the reserve light comes on, the driving-distance-on-remaining-fuel (trip computer) is calculated by monitoring the fuel consumption signal, and continues until the fuel tank is empty (or refilled).

In the case of the 911 Carrera 4 (996), the shape and configuration of the fuel tank prevent the fuel level sensing system from being able to physically read down to a level of 10 litres. Therefore, on the 911 Carrera 4 the driving-distance-on-remaining-fuel calculation begins when the fuel reaches a level of 19 litres (approx. 1/4 tank). As fuel is further consumed below 19 litres, the amount of fuel remaining in the tank is a calculated value. The calculated value is derived from the fuel consumption signal, and continues until the fuel tank is empty (unless the fuel tank is refilled).

Thus, if the fuel level is low, and less than 19 litres of fuel are added, the added fuel may not be recorded by the fuel gauge, and the range may not be recalculated."

chrisH · Nov 30, 2008

Rodney,
Thanks for sharing that. Its the 997 GEN II, C2 I have out on demo not C4.
I wonder what the range figure will show when the existing range, (45 mls) is used up, even though there is more fuel in the tank ( added 3gals or 13 ltires in my case) capable of another 75 mls.
Chris

garyw · Nov 30, 2008

As pointed out, its a common feature [&:]
happened on my 996 and still on my 997, a little more prone on 4wd models due to the two part/sided tank

garyw

chrisH · Dec 1, 2008

I took the demo back today and the range was blank by then and the gauge below the lowest mark. All seems a bit wierd when you actually just put in over 3 gals. The OPC said the C4 has saddle tanks and maybe because the C2 I had was a PDK maybe that also has the same tank.
On the positive side the PDK was impressive, very high 7th gear as I said already although I wouldn't fork out 2k for it, also the touchscreen for radio etc.
Thanks to everyone who let me know about this design quirk, so I could relax about it today.
Chris

dereksharpuk · Dec 2, 2008

So having been lent a lovely 911, you took it back with absolutely zero fuel in it; diddly squat?

I remember once, when I delivered a few Porsches, I collected a 911 from a chap in the country, miles from any garage, and the fuel gauge was below the minimum mark and the range = zero. I asked the chap how was I expected to get to the nearest petrol station and he just shugged his shoulders and said. "Your problem mate". What a nice chap I thought!

Peter_Bull · Dec 3, 2008

HE seemed a nice chat Derek - not!
I bet his car suffered after you got some juice in it eh?? Go on tell us!

dereksharpuk · Dec 3, 2008

ORIGINAL: Peter Bull

HE seemed a nice chat Derek - not!
I bet his car suffered after you got some juice in it eh?? Go on tell us!

No, my point was that the OPC lent him a car for trial and like many he returned it totally empty. Most also just return it with a litre of petrol and about 30 miles range. This guy milked it (literally) for all he could. I'm surprised that he did not take the spare wheel out of the car.

Dylan1 · Dec 3, 2008

if he took the car out with only 3 galls in and brought it back with the same then i think thats fair enough-i wouldnt take a test drive and fill it up before taking it back(unless full when taken out).if however it was full at start of test then leaving it nearly empty would not be decent behaviour(imo).i dont think we have sufficient information to comment with accuracy

dereksharpuk · Dec 3, 2008

ORIGINAL: dyllan

if he took the car out with only 3 galls in and brought it back with the same then i think thats fair enough-i wouldnt take a test drive and fill it up before taking it back(unless full when taken out).if however it was full at start of test then leaving it nearly empty would not be decent behaviour(imo).i dont think we have sufficient information to comment with accuracy

Yes I agree totally & who are we to judge, but Chris has admitted that he returned the car with absolutely zero fuel and the range showing blank. However, I would not accept a vehicle with an empty tank in the first place. Moreover, I would point out to the dealership that it is hardly good customer relations offering a car for demonstration with the fuel guage reading zero and the range showing also zero. I don't know the full facts of this case, but I can't believe any decent OPC would offer a car with absolutely nothing in it! Even if the vehicle is slightly dirty my OPC always offers apologies and a reason why.

Rodney Naghar · Dec 3, 2008

I was given a loan car by an OPC that had so little fuel in it that I had to coast as far as I could to the nearest petrol station in fear of running out.
The service advisor apologised to me before taking the car out and said he would put a note in the system that I should be refunded on return. Obviously on returning the loan car, said note was missing. [

]

dereksharpuk · Dec 3, 2008

ORIGINAL: Rodney Naghar

I was given a loan car by an OPC that had so little fuel in it that I had to coast as far as I could to the nearest petrol station in fear of running out.
The service advisor apologised to me before taking the car out and said he would put a note in the system that I should be refunded on return. Obviously on returning the loan car, said note was missing. []

That is obviously terrible service! My OPC supplies clean loan cars with full tanks, but ask that the car is returned in the same condition. Demonstrators may not be full, but must have at least a quarter of a tank. As part of your expensive service, you have a right to a decent loan car and I would personally have spoken to the dealer principle if I got that sort of service (plus sent a snotogram to Porsche Cars GB) [

]. Why not name and shame?

chrisH · Dec 3, 2008

ORIGINAL: dereksharpuk

ORIGINAL: dyllan

if he took the car out with only 3 galls in and brought it back with the same then i think thats fair enough-i wouldnt take a test drive and fill it up before taking it back(unless full when taken out).if however it was full at start of test then leaving it nearly empty would not be decent behaviour(imo).i dont think we have sufficient information to comment with accuracy

Click to expand...

Yes I agree totally & who are we to judge, but Chris has admitted that he returned the car with absolutely zero fuel and the range showing blank. However, I would not accept a vehicle with an empty tank in the first place. Moreover, I would point out to the dealership that it is hardly good customer relations offering a car for demonstration with the fuel guage reading zero and the range showing also zero. I don't know the full facts of this case, but I can't believe any decent OPC would offer a car with absolutely nothing in it! Even if the vehicle is slightly dirty my OPC always offers apologies and a reason why.

Derek,
If you read my post I did say I had only just put 3 gals in it, actually £15 is 16.5 litres. Even if I had put more in it the fuel system would still not register unless at least 19 litres are added, I am told, so what was the point?
For the record, they said don't bother to fuel it as it was only 1/4 full when collected.
Chris

garyw · Dec 3, 2008

I've put my car in for service with the fuel light on.!!
I'd actually put £20 of cheap stuff in locally to the OPC but it never registered..
I did point it out at reception who seemed to think it was the norm..[

]

garyw