Poor Gas Mileage?
#46
01-27-2009, 11:25 AM
You guys need to man up and grow a pair 
Let that car idle for 15 to 30 seconds and that start driving in your icy tomb. Take one for the longevity of your motor, cats, MPGs, and the environment. On a 10 degree day with the car sitting outside for 8 hours, I can have the temp gauge at the middle level within 1 mile of driving. However, this isn't to say the entire drivetrain is fully warmed up, but at least I'm getting full on heat. I've noticed that the tranny fluid takes solid 5 minutes of steady driving to fully warm up in sub 30 degree air.
Let that car idle for 15 to 30 seconds and that start driving in your icy tomb. Take one for the longevity of your motor, cats, MPGs, and the environment. On a 10 degree day with the car sitting outside for 8 hours, I can have the temp gauge at the middle level within 1 mile of driving. However, this isn't to say the entire drivetrain is fully warmed up, but at least I'm getting full on heat. I've noticed that the tranny fluid takes solid 5 minutes of steady driving to fully warm up in sub 30 degree air.
#47
01-27-2009, 11:25 AM
DaveB is correct!!! To piggyback on his comments, in ancient times when carburators were used, there was this unwritten law about warming up your car before driving. The law was deeply rooted in poor vaporization of the gas in a cold carburator and intake manifold. At that time, warming up the engine was supposed to eliminate hesitation and stalling. However, what they didn't know then was that extended warmup (>3-5 minutes) could actually cause damage to the engine by diluting the oil with excess fuel, and it could also result in hot spots in the combustion chamber (which over time causes uneven micro-wear on the rings and combustion chamber).
A cold engine experiences excessive wear due to the rich mixture required by the EFI system. This tends to wash fuel from the cylinder walls and aggravates wear between the rings and cylinder bores. Engineers include in the ECU an analytical/semi-empirical mathematical model of the heat transfer within the engine. It is basically a super-thermostat. The ECU uses information from various temp- and flow-sensors to adjust the parameters that affect an engine heating: coolant flow, richness of the mixture, etc. This is all designed to heat up the engine as quickly as possible.
An engine that is driven immediately (but slowly for the initial 200-300 yards) will have much higher coolant and oil temperatures than one that idles for 5 minutes. At the same time you will also warm up the rest of the drivetrain like the transmission and wheel bearings. Something idling can not do.
My suggestion is 15-30 seconds to let the oil circulate throughout the engine (it takes this long for colder climates), and then drive out slowly for the initial 1/4 mile.
Finally, winter gas is made to evaporate faster and cause better starts during cold weather, one reason for the lower mpg.
A cold engine experiences excessive wear due to the rich mixture required by the EFI system. This tends to wash fuel from the cylinder walls and aggravates wear between the rings and cylinder bores. Engineers include in the ECU an analytical/semi-empirical mathematical model of the heat transfer within the engine. It is basically a super-thermostat. The ECU uses information from various temp- and flow-sensors to adjust the parameters that affect an engine heating: coolant flow, richness of the mixture, etc. This is all designed to heat up the engine as quickly as possible.
An engine that is driven immediately (but slowly for the initial 200-300 yards) will have much higher coolant and oil temperatures than one that idles for 5 minutes. At the same time you will also warm up the rest of the drivetrain like the transmission and wheel bearings. Something idling can not do.
My suggestion is 15-30 seconds to let the oil circulate throughout the engine (it takes this long for colder climates), and then drive out slowly for the initial 1/4 mile.
Finally, winter gas is made to evaporate faster and cause better starts during cold weather, one reason for the lower mpg.
#48
01-27-2009, 11:58 AM
My kids refer to me as the "Gestapo" when it comes to these matters..... "Cold? Great!!! Now put on a jacket and live thru it like the rest of the world!" Of course, if they were much younger (<7), I would be much more gentle. You make a good point!
#49
01-27-2009, 12:17 PM
The really great problem with these lengthy warm-ups is that if you're not in the car and something goes wrong (e.g., a chain of events wherein the engine overheats due to a blocked radiator core and the sensors don't pick it up in time, et.), you're not there to stop the damage. Sorta like leaving a baby unattended in the living room while you go out for a 10 minute smoke.
#51
01-27-2009, 12:55 PM
Janik...I wish you could see the finger I'm giving you right now. 
I don't even have a garage at all. My baby sits out in the elements every night. I'm workin on it though. Hopefully this is the only winter she has to see. I'm trying to buy a house in September, when my lease is up.
Anyways, I usually Idle my car for about 3-5 minutes while I stand next to it and smoke a cig. Smoking in the G FTL!
I don't even have a garage at all. My baby sits out in the elements every night. I'm workin on it though. Hopefully this is the only winter she has to see. I'm trying to buy a house in September, when my lease is up.
Anyways, I usually Idle my car for about 3-5 minutes while I stand next to it and smoke a cig. Smoking in the G FTL!
#54
01-27-2009, 01:23 PM
lol. My kids are 5, 2, and 4-months, so can't give them that treatment yet.
#55
01-27-2009, 01:23 PM
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It is amazing what some of my neighbors do when its cold or very cold. They warm their car up for 15-20 minutes consistently everyday. Some are worse than others but my god they are wasting so much gas and wear and tear.
Mine is garage kept so I am lucky. I always let it run for 15-20 seconds and drive off slowly. Usually by the time I am out of the neighborhood or on main streets the car is warming up nicely.
My mileage has fallen off by as much as 2mpg in the colder months. Usually I average about 19mpg.
Mine is garage kept so I am lucky. I always let it run for 15-20 seconds and drive off slowly. Usually by the time I am out of the neighborhood or on main streets the car is warming up nicely.
My mileage has fallen off by as much as 2mpg in the colder months. Usually I average about 19mpg.
#56
01-27-2009, 01:25 PM
#57
01-27-2009, 01:25 PM
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well maybe we will be neighbors some day. 
*picture us both walking out one morning and getting in the gs. "Good morning Brandon." "Good morning Janik." "Have a nice day!" "you too!"*
#58
01-27-2009, 07:55 PM
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When it's -24F I will warm up my car for 10-15m and turn on the heated seats. My drive to work is only 5 minutes so I want to try and get all the moisture out of the system as I can. I will drive it on the highway during the week to "dry" out the system, especially the exhaust system. By the way, ethenol su__ks for all the reasons you all know, including worse performance, worse gas mileage, etc. and I live in Minnesota where corn is a huge crop and ethenol plants thrive.
#60
01-27-2009, 09:27 PM
When it's -24F I will warm up my car for 10-15m and turn on the heated seats. My drive to work is only 5 minutes so I want to try and get all the moisture out of the system as I can. I will drive it on the highway during the week to "dry" out the system, especially the exhaust system. By the way, ethenol su__ks for all the reasons you all know, including worse performance, worse gas mileage, etc. and I live in Minnesota where corn is a huge crop and ethenol plants thrive.