Alfa Romeo Giulia Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter · #1 ·
Noticed this in the manual today. We're being told to "top off twice" in order to "ensure that you fill the tank completely".

Does this mean that after the first "click", you're supposed to start another round of filling until you hear a second click? Or am I completely misunderstanding this?

Have I not been filling up the tank all the way this whole time? The gauge already reads "full" if you stop after the first click...
 

Attachments

·
Registered
Joined
·
1,955 Posts
Interesting.
Overfilling CAN cause problems with the fuel storage-delivery system and set codes.
How much more fuel is delivered when you add to the second click?
 

·
Registered
2017 Alfa Romeo Giulia Quadrifoglio
Joined
·
953 Posts
I’ve actually always done two subsequent clicks after the first fuel stop as per the manual. Never had issues.
 

·
Registered
Joined
·
244 Posts
Gas nozzles have a small hole near the tip which sucks up air and when the gas rises up enough to block the hole you have that click. Assuming the nozzle doesn't end right at the gas door, you still have a bit of empty space in the tank for one or two more clicks.
 

·
Registered
Joined
·
39 Posts
I use Fuelly to track MPGs so I want consistency. Consequently I always stop at the first click. I try to always fill up between 1/4 to 1/3 anyway, so the little bit extra doesn’t really matter to me.
 

·
Registered
Joined
·
45 Posts
"Further top-off could cause faults in the fuel feeding system"

Right, so first click stop for me then. The extra couple of ounces of fuel does not seem worth the risk.
 

·
Registered
2020 Alfa Romeo Giulia Sport Ti AWD
Joined
·
7,385 Posts
Whatever happened to whole dollar amount?
 

·
Registered
Joined
·
27 Posts
Discussion Starter · #8 ·
I’ve actually always done two subsequent clicks after the first fuel stop as per the manual. Never had issues.
Interesting, that's good to know. I haven't been brave enough to keep filling after the first click, but maybe next time I'll go for a second click.
 

·
Registered
Joined
·
1,807 Posts
Just a different perspective...

Absolute accuracy in MPG for my Giulia = Not Life Altering and Not Annoying

VS.

Giulia throwing a fuel code = Life Altering and Annoying
 

·
Registered
Joined
·
1,955 Posts
Just a different perspective...

Absolute accuracy in MPG for my Giulia = Not Life Altering and Not Annoying

VS.

Giulia throwing a fuel code = Life Altering and Annoying
Word.
Having just received our MY18 Ti, and not having had to fill the tank (it was delivered with what seemed to be a full tank), I have not had he opportunity to check my MPG. At about100 miles, the instrument panel MPG indicator is reading 21.7.
I wonder, has anyone here performed the math, with every fill up, to check the accuracy of the IP readout? Our 01 BMW 530i, which we have had for years, and over 200,000 miles, is dead on accurate.
 

·
Registered
Joined
·
45 Posts
I wonder, has anyone here performed the math, with every fill up, to check the accuracy of the IP readout?
My guess is the cars are more accurate that we could ever be. I assume there is a flow meter in the fuel system somewhere for gallons as well as the odometer for the miles per. Simple math in the ECU is all that's required. The number is probably dead on.
 

·
Registered
Joined
·
149 Posts
I've seen issues with other cars when trying to "top off" every time, specifically some MBs I've owned.

Now, I just fill until it stops without trying to get as much gas as I can into the tank. It was hard at first, as I've gone a lifetime trying to get to the closest dollar.

Steve
 

·
Registered
Joined
·
1,807 Posts
I just put in $20 every so often and the fuel is fresh and I'm in and out pretty fast....Never let it go below 1/4 tank....D
 
  • Like
Reactions: AlfaAndy and recoil

·
Registered
Joined
·
1,999 Posts
Word.
Having just received our MY18 Ti, and not having had to fill the tank (it was delivered with what seemed to be a full tank), I have not had he opportunity to check my MPG. At about100 miles, the instrument panel MPG indicator is reading 21.7.
I wonder, has anyone here performed the math, with every fill up, to check the accuracy of the IP readout? Our 01 BMW 530i, which we have had for years, and over 200,000 miles, is dead on accurate.
Yes and no:

http://www.giuliaforums.com/forum/8...irst-cut-fuel-level-indications-quantity.html

In my experience, the mile to go feature is horribly inaccurate. I can drive 10 miles at a quarter tank and go from 128 miles to go to 60-70 miles to go, and have several times gathering data. MPG appears to be off by between .2 and 1 MPG, depends.
 

·
Registered
Joined
·
1,568 Posts
Miles to go counter is not very sophisticated as it does not average the consumption over longer period of time.....it can go up and own very rapidly depending on your current consumption..i have seen it go from 300 to 90 and back to 300 within 20 minutes
 

·
Registered
Joined
·
105 Posts
My guess is the cars are more accurate that we could ever be. I assume there is a flow meter in the fuel system somewhere for gallons as well as the odometer for the miles per. Simple math in the ECU is all that's required. The number is probably dead on.
I would be very surprised if that were the case. I do not know of any car that has a true fuel meter in the system. Fuel injection systems control flow through very accurate control of the time intervals that the injectors are open. They are extremely accurate in adjusting when more fuel or less fuel is required to get a specific mixture, and they refer to maps that plot time open against numerous other variables but because there are variations in fuel pressure under different conditions, time open on an injector does not reference an exact volume of fuel. Every system that I have been familiar with does not actually measure flow directly but rather flow or volume consumed is merely a mathematical model based on average flows and time. As such the gallon estimate is just that, an estimate, based on rough data whereas the actual mixtures employed in combustion are very precise based on air meter reads and O2 sensor data.
 

·
Registered
Joined
·
1,955 Posts
I would be very surprised if that were the case. I do not know of any car that has a true fuel meter in the system. Fuel injection systems control flow through very accurate control of the time intervals that the injectors are open. They are extremely accurate in adjusting when more fuel or less fuel is required to get a specific mixture, and they refer to maps that plot time open against numerous other variables but because there are variations in fuel pressure under different conditions, time open on an injector does not reference an exact volume of fuel. Every system that I have been familiar with does not actually measure flow directly but rather flow or volume consumed is merely a mathematical model based on average flows and time. As such the gallon estimate is just that, an estimate, based on rough data whereas the actual mixtures employed in combustion are very precise based on air meter reads and O2 sensor data.
My understanding of how the system calculates the MPG, is that it uses the information from the fuel-ignition ecu (which knows the quantity and dwell of the fuel injector openings), and the miles driven. With that information, imo, it can calculate very accurately. I know that in my BMWs, it is VERY accurate. As for the "miles to empty" function, that is somewhat of a guess.
 

·
Registered
Joined
·
105 Posts
My understanding of how the system calculates the MPG, is that it uses the information from the fuel-ignition ecu (which knows the quantity and dwell of the fuel injector openings), and the miles driven. With that information, imo, it can calculate very accurately. I know that in my BMWs, it is VERY accurate. As for the "miles to empty" function, that is somewhat of a guess.
Yes, I agree, most (if not all) modern cars measure exactly like that, not with a fuel meter. But because fuel pressure varies under transition conditions, the number of injector openings multiplied by the the varied durations is not an exact proxy for a direct fuel meter reading. Given sophisticated algorithms to translate into volume, it can be very accurate but there do seem to be variations under different conditions and from manufacturer to manufacturer. My 2012 135i is more accurate than my Alfa under some conditions. Others, like Toyota always seem to come out notably optimistic. My point was that fuel volume measurements are a derived calculation involving summation of millions of FI pulses with assorted correction factors for different conditions, not a direct read.
 
  • Like
Reactions: AlfaAndy
1 - 19 of 19 Posts
Top