Fuel Consumption constantly rising when stopped
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AudiWorld Newcomer
Joined: Jan 2018
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Fuel Consumption constantly rising when stopped
First off all apologies if there is already info on this, but I couldn't find anything similar...except a youtube video with the problem, but no solution.
The car is an S6 C5 from 2000 ANK, with 230000 km on the ODO, LPG, with replaced one pre-cat O2, and replaced vacuum lines, cleaned TB, 8 new spark plugs and 2 new ignition coils... NO CODES whatsoever.
Short term fuel trim on the Bank 1 is a bit off, but acceptable as there is no code.
Cats are emptied, post cat foulers installed.
Car runs like a train, but consumption is still somewhat on the high side.
Now the biggest/strangest problem: When stationary and engine running, at a light for example:
1. The instant consumptions never shows the same numbers. (like consumption per hour). it randomly stops at a number...
2. The average consumption keeps climbing... depending how long you stand still, it will go as much as few liters...that can't be right...
Thoughts, ideas,experiences
Very grateful to all!
The car is an S6 C5 from 2000 ANK, with 230000 km on the ODO, LPG, with replaced one pre-cat O2, and replaced vacuum lines, cleaned TB, 8 new spark plugs and 2 new ignition coils... NO CODES whatsoever.
Short term fuel trim on the Bank 1 is a bit off, but acceptable as there is no code.
Cats are emptied, post cat foulers installed.
Car runs like a train, but consumption is still somewhat on the high side.
Now the biggest/strangest problem: When stationary and engine running, at a light for example:
1. The instant consumptions never shows the same numbers. (like consumption per hour). it randomly stops at a number...
2. The average consumption keeps climbing... depending how long you stand still, it will go as much as few liters...that can't be right...
Thoughts, ideas,experiences
Very grateful to all!
AudiWorld Member
Joined: Oct 2003
Posts: 198
Likes: 15
What else can you expect? You are sitting still but still burning fuel to keep the engine turning over. This is why so many modern cars have engine stop-start systems now to help their trip efficiency.
In the US, where our dash displays distance/volume rather than volume/distance, I think the instantaneous display also freezes on every Audi model I've driven. The ratio fuel/zero distance is ill-defined and Audi decided to halt the display rather than be cheeky and display an infinity symbol. When you engine-brake or coast down steep hills you can also see the instantaneous display change to "---" once the opposite happens, and you are covering so much distance with so little fuel consumption that they do not have the display digits necessary to show the ratio.
Since the average display is computing a ratio of two sums which are both non-zero, it can keep updating as the fuel sum increases and the distance sum stays fixed. If you reset the average display while stationary, it also will be frozen and won't display a value until you drive far enough for it to start showing a plausible value again.
In the US, where our dash displays distance/volume rather than volume/distance, I think the instantaneous display also freezes on every Audi model I've driven. The ratio fuel/zero distance is ill-defined and Audi decided to halt the display rather than be cheeky and display an infinity symbol. When you engine-brake or coast down steep hills you can also see the instantaneous display change to "---" once the opposite happens, and you are covering so much distance with so little fuel consumption that they do not have the display digits necessary to show the ratio.
Since the average display is computing a ratio of two sums which are both non-zero, it can keep updating as the fuel sum increases and the distance sum stays fixed. If you reset the average display while stationary, it also will be frozen and won't display a value until you drive far enough for it to start showing a plausible value again.
Thread Starter
AudiWorld Newcomer
Joined: Jan 2018
Posts: 2
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Thank you!
I forgot to mention I am new to the C5 scene...I also have a C6 2.7 TDI , and it's a different story there. Previously been a VW driver forever and just assumed Audi is the same.
In any case this feels good, as I don't have to chase a problem.
Took it for a spin on the highway over the WE, and it dropped down few liters, starting to look normal.
But from what you all are saying I shouldn't count on the accuracy of the average consumption meter. I will try to measure from tank full to tank full.
I forgot to mention I am new to the C5 scene...I also have a C6 2.7 TDI , and it's a different story there. Previously been a VW driver forever and just assumed Audi is the same.
In any case this feels good, as I don't have to chase a problem.
Took it for a spin on the highway over the WE, and it dropped down few liters, starting to look normal.
But from what you all are saying I shouldn't count on the accuracy of the average consumption meter. I will try to measure from tank full to tank full.
AudiWorld Senior Member
Joined: Jan 2015
Posts: 1,186
Likes: 43
From: Sierra Vista, AZ
You can do all that math if you wish. The consumption reading on the display is derived from the fuel flow activity through the electronic fuel injection system and is about as accurate as you can get. You should be able to scroll through the menu and get average consumption on the trip meter that most folks reset every time they fill up.
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