Does the cold lean out my car?
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Joined: 04-11-07
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From: Salem, OH
Does the cold lean out my car?
So i have been driving around lately in 20deg weather and my car is suffering on power. Yeah its only a 2.2 but i have intake exhaust..... I was wondering if the cold temps cause my A/F ration to go lean reducing the power (which pisses me off cuz the car is slow already) also there are little knocks.... not anything to worry bout but was wondering if its just the cold that is doin this. BTW the car is in top shape.....no engine problems at all...ever
actualy, some of thats not true.
when you get colder air, it becomes more dense. denser air= more oxogen in a smaller area, so for the same volume of air taken in, you need more air to maintain a given air fuel ratio.
however, with fuel injection, more dense air does not mean you will run leaner. the computer is programmed to compensate for weather changes. using the maf, map, and iat, the computer calculates the fuel required to keep the motor running at its optimal a/f ratio and ignition timing.
also, leaner doesnt mean more power, quite the oposite. with gasoline, you have a stoichiometrioc ratio (a/f ratio were you have a perfect burn, no left over oxogen or fuel) of 14.7:1, however its best to cruise leaner than that (higher), around 15.5-17:1, and best power n/a usualy falls around 12.5-13.2. if your engine get leaner than that range, it will actualy make less power, however when that happens you usualy feel it bog down and doesnt cause damage
just to add to this, other fuel are different, take methanol for example. stoich is around 6:1, and leaner will actualy make more power. tuning with alcohol is tougher being that the car will make more and more power untill it melts a piston.
when you get colder air, it becomes more dense. denser air= more oxogen in a smaller area, so for the same volume of air taken in, you need more air to maintain a given air fuel ratio.
however, with fuel injection, more dense air does not mean you will run leaner. the computer is programmed to compensate for weather changes. using the maf, map, and iat, the computer calculates the fuel required to keep the motor running at its optimal a/f ratio and ignition timing.
also, leaner doesnt mean more power, quite the oposite. with gasoline, you have a stoichiometrioc ratio (a/f ratio were you have a perfect burn, no left over oxogen or fuel) of 14.7:1, however its best to cruise leaner than that (higher), around 15.5-17:1, and best power n/a usualy falls around 12.5-13.2. if your engine get leaner than that range, it will actualy make less power, however when that happens you usualy feel it bog down and doesnt cause damage
just to add to this, other fuel are different, take methanol for example. stoich is around 6:1, and leaner will actualy make more power. tuning with alcohol is tougher being that the car will make more and more power untill it melts a piston.
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Joined: 03-03-06
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From: Pittsburgh, PA
actualy, some of thats not true.
when you get colder air, it becomes more dense. denser air= more oxogen in a smaller area, so for the same volume of air taken in, you need more air to maintain a given air fuel ratio.
however, with fuel injection, more dense air does not mean you will run leaner. the computer is programmed to compensate for weather changes. using the maf, map, and iat, the computer calculates the fuel required to keep the motor running at its optimal a/f ratio and ignition timing.
also, leaner doesnt mean more power, quite the oposite. with gasoline, you have a stoichiometrioc ratio (a/f ratio were you have a perfect burn, no left over oxogen or fuel) of 14.7:1, however its best to cruise leaner than that (higher), around 15.5-17:1, and best power n/a usualy falls around 12.5-13.2. if your engine get leaner than that range, it will actualy make less power, however when that happens you usualy feel it bog down and doesnt cause damage
just to add to this, other fuel are different, take methanol for example. stoich is around 6:1, and leaner will actualy make more power. tuning with alcohol is tougher being that the car will make more and more power untill it melts a piston.
when you get colder air, it becomes more dense. denser air= more oxogen in a smaller area, so for the same volume of air taken in, you need more air to maintain a given air fuel ratio.
however, with fuel injection, more dense air does not mean you will run leaner. the computer is programmed to compensate for weather changes. using the maf, map, and iat, the computer calculates the fuel required to keep the motor running at its optimal a/f ratio and ignition timing.
also, leaner doesnt mean more power, quite the oposite. with gasoline, you have a stoichiometrioc ratio (a/f ratio were you have a perfect burn, no left over oxogen or fuel) of 14.7:1, however its best to cruise leaner than that (higher), around 15.5-17:1, and best power n/a usualy falls around 12.5-13.2. if your engine get leaner than that range, it will actualy make less power, however when that happens you usualy feel it bog down and doesnt cause damage
just to add to this, other fuel are different, take methanol for example. stoich is around 6:1, and leaner will actualy make more power. tuning with alcohol is tougher being that the car will make more and more power untill it melts a piston.
The bolded part being the most important part here. If the MAF is calibrated correctly across all possible frequencies in its operating range, the car will usually not lean out due to a temperature change.
If you have a shitty calibration (read custom tune) that isn't calibrated correctly at higher airflow readings is when you have problems.
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