ok thanks Calvin, there's fuel trims and timing calcs i guess. my guy backed off my inj duty cycles because he said it was rich, but that was correcting a previous re-prog
Which obtains better MPG: K & N or paper filter?
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Originally Posted By: [RT
ProjUltraZ]ok thanks Calvin, there's fuel trims and timing calcs i guess. my guy backed off my inj duty cycles because he said it was rich, but that was correcting a previous re-prog
There are still values stored in the programing that act like "stops" to give the ECU its working range for both timing and fuel trim. Bumping up against one of these and staying there will set a code, usually something like "o2 failure to switch lean/rich". Depending on the exact ECU it will also usually remember what a value for "best guess" is to get itself started. Probably one of these was set too aggressively.
Also, if this is some race setup then it will be using the maps a lot more because you'll be at WOT a lot more. On the street they aren't used as much unless you drive like a nut.
ProjUltraZ]ok thanks Calvin, there's fuel trims and timing calcs i guess. my guy backed off my inj duty cycles because he said it was rich, but that was correcting a previous re-prog
There are still values stored in the programing that act like "stops" to give the ECU its working range for both timing and fuel trim. Bumping up against one of these and staying there will set a code, usually something like "o2 failure to switch lean/rich". Depending on the exact ECU it will also usually remember what a value for "best guess" is to get itself started. Probably one of these was set too aggressively.
Also, if this is some race setup then it will be using the maps a lot more because you'll be at WOT a lot more. On the street they aren't used as much unless you drive like a nut.
Originally Posted By: SuperBusa
Originally Posted By: BuickGN
Seriously guys, how many times does this have to be said. I've even linked to the govenment study on this. More air= more fuel being used. Less air = less fuel.
The throttle plate is the largest restriction. If the other logic were true, cars would get their best mileage at wide open throttle.
The fact is, if you want to make your car do a steady 60 MPH down the road it's going to take XX HP to do so. XX HP is achieved by burning a specific amount of air + fuel mixture. FI engines control the AF via O2 sensor feedback when cursing steady-state and in closed-loop mode.
Therefore, if an air filter is more restrictive from being dirty, it's just going to take a hair more throttle to achieve that 60 MPH HP level.
The only time you could probably see a difference on any engine (FI or not) is at WOT because then the reduction of air flow rate (from a dirty filter) would be evident because you can't compensate with any more throttle beyond WOT.
100% agreed.
Originally Posted By: BuickGN
Seriously guys, how many times does this have to be said. I've even linked to the govenment study on this. More air= more fuel being used. Less air = less fuel.
The throttle plate is the largest restriction. If the other logic were true, cars would get their best mileage at wide open throttle.
The fact is, if you want to make your car do a steady 60 MPH down the road it's going to take XX HP to do so. XX HP is achieved by burning a specific amount of air + fuel mixture. FI engines control the AF via O2 sensor feedback when cursing steady-state and in closed-loop mode.
Therefore, if an air filter is more restrictive from being dirty, it's just going to take a hair more throttle to achieve that 60 MPH HP level.
The only time you could probably see a difference on any engine (FI or not) is at WOT because then the reduction of air flow rate (from a dirty filter) would be evident because you can't compensate with any more throttle beyond WOT.
100% agreed.
Now that was more info then I need, best mileage suggestions: good tune-up, clean air filter, and the No. 1 mileage improver is drop ur speed to 63 mph on the interstate and use that cruise control, and throw u male ego out the window. Works for me.
"Because the diesel engine is unthrottled, and airflow is high even at light load, the added restriction from a clogged filter may have a measureable effect on fuel economy."
This was from the 2009 study conclusions and I agree with this statement.
I can add that most diesels have less air-fuel decisions made by the ECM than a gasoline engine...but that has probably changed as of late with the emissions requirements.
That said, diesels don't typically "defuel" based on air flow...so you can pump X amount of fuel into the cylinders with a clean or dirty filter, and the ECM doesn't know the airflow decreased to compensate with Z fueling.
This was from the 2009 study conclusions and I agree with this statement.
I can add that most diesels have less air-fuel decisions made by the ECM than a gasoline engine...but that has probably changed as of late with the emissions requirements.
That said, diesels don't typically "defuel" based on air flow...so you can pump X amount of fuel into the cylinders with a clean or dirty filter, and the ECM doesn't know the airflow decreased to compensate with Z fueling.
Originally Posted By: calvin1
which ever one is the MOST restrictive - less air in means less fuel in (assuming an otherwise properly functioning EFI system)
You do realize an engine is just an air pump. The more air in, the more power you make and the more efficient the engine is as well. So restricting air would not make the engine more efficient.
which ever one is the MOST restrictive - less air in means less fuel in (assuming an otherwise properly functioning EFI system)
You do realize an engine is just an air pump. The more air in, the more power you make and the more efficient the engine is as well. So restricting air would not make the engine more efficient.
In a modern diesel the engine DOES measure airflow in.
That's too critical of a stat to ignore!
That's too critical of a stat to ignore!
Originally Posted By: pavelow
Originally Posted By: calvin1
which ever one is the MOST restrictive - less air in means less fuel in (assuming an otherwise properly functioning EFI system)
You do realize an engine is just an air pump. The more air in, the more power you make and the more efficient the engine is as well. So restricting air would not make the engine more efficient.
power is the opposite of mpg - this thread is about mpg
Originally Posted By: calvin1
which ever one is the MOST restrictive - less air in means less fuel in (assuming an otherwise properly functioning EFI system)
You do realize an engine is just an air pump. The more air in, the more power you make and the more efficient the engine is as well. So restricting air would not make the engine more efficient.
power is the opposite of mpg - this thread is about mpg
In general, the less restriction placed on an engine = less pumping losses = more MPG. But I have a feeling that you'd need a *really* loaded air filter to decrease measureable milage in any modern EFI engine.
There's many other factors involved that restrict the intake/exaust gasses; the most being your foot
There's many other factors involved that restrict the intake/exaust gasses; the most being your foot
Originally Posted By: Virtuoso
In general, the less restriction placed on an engine = less pumping losses = more MPG. But I have a feeling that you'd need a *really* loaded air filter to decrease measureable milage in any modern EFI engine.
There's many other factors involved that restrict the intake/exaust gasses; the most being your foot
Exactly.
I don't disagree that pumping losses are a factor in ICE efficiency but it's a microscopic effect compared to everything else. Also, efficiency can mean many things. It can mean the most horse-power/gallon or the most miles/gallon. If you're at WOT then it's worth it to go looking at the sources of intake restriction BUT you can't be too worried about your mileage if that's how you're driving. Driving for the gas mileage kind of efficiency means staying as close to closed throttle as possible, one side effect of which will be maximizing your pumping losses even if you had NO air filter. You can't have it both ways.
In general, the less restriction placed on an engine = less pumping losses = more MPG. But I have a feeling that you'd need a *really* loaded air filter to decrease measureable milage in any modern EFI engine.
There's many other factors involved that restrict the intake/exaust gasses; the most being your foot
Exactly.
I don't disagree that pumping losses are a factor in ICE efficiency but it's a microscopic effect compared to everything else. Also, efficiency can mean many things. It can mean the most horse-power/gallon or the most miles/gallon. If you're at WOT then it's worth it to go looking at the sources of intake restriction BUT you can't be too worried about your mileage if that's how you're driving. Driving for the gas mileage kind of efficiency means staying as close to closed throttle as possible, one side effect of which will be maximizing your pumping losses even if you had NO air filter. You can't have it both ways.
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