Warming Up Car
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Joined: Aug 2007
Posts: 10,850
Likes: 158
From: Los Angeles
Originally Posted by nghiars
the manual says it takes the enigne 30 secs to get the enigne fully lubricated. i try to let it get to 1k rpm but if im in a hurry, i'll wait 30 secs... plus im i socal so how cold does it reeally get
#26
Originally Posted by nghiars
the manual says it takes the enigne 30 secs to get the enigne fully lubricated. i try to let it get to 1k rpm but if im in a hurry, i'll wait 30 secs... plus im i socal so how cold does it reeally get
if i'm in a hurry i'll wait 30 seconds and drive softly, if i got a few minutes, i'll sit until the RPM reaches 1k or lower and try to sort out the day's schedule in my brain
#27
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.
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 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, and then out slowly for the initial mile.
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 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, and then out slowly for the initial mile.
Last edited by Braintree; 11-07-2008 at 03:51 PM.
#28
Braintree. Nice post but I have to disagree on a few points.
ECU controlled cars during warm up are in open loop mode. In this mode only a limited amount of sensors are used and the ecu is using a set of maps stored in it's memory vs using the 02 sensor etc.. to adjust the a/f ratios.
Once the ecu sees the coolant temp rise to a certain temp, it then goes into closed loop mode and uses all the sensors to adjust the engine parameters.
Also oil circulation is done probably within 5 seconds of the engine startup (probably sooner). If it actually took 15-30 seconds for the engine to see complete oil circulation, the engine would most likely be experiencing oil starvation damage.
Other than that, great post.
ECU controlled cars during warm up are in open loop mode. In this mode only a limited amount of sensors are used and the ecu is using a set of maps stored in it's memory vs using the 02 sensor etc.. to adjust the a/f ratios.
Once the ecu sees the coolant temp rise to a certain temp, it then goes into closed loop mode and uses all the sensors to adjust the engine parameters.
Also oil circulation is done probably within 5 seconds of the engine startup (probably sooner). If it actually took 15-30 seconds for the engine to see complete oil circulation, the engine would most likely be experiencing oil starvation damage.
Other than that, great post.
#29
Originally Posted by Jeff92se
Braintree. Nice post but I have to disagree on a few points.
ECU controlled cars during warm up are in open loop mode. In this mode only a limited amount of sensors are used and the ecu is using a set of maps stored in it's memory vs using the 02 sensor etc.. to adjust the a/f ratios.
Once the ecu sees the coolant temp rise to a certain temp, it then goes into closed loop mode and uses all the sensors to adjust the engine parameters.
Also oil circulation is done probably within 5 seconds of the engine startup (probably sooner). If it actually took 15-30 seconds for the engine to see complete oil circulation, the engine would most likely be experiencing oil starvation damage.
Other than that, great post.
ECU controlled cars during warm up are in open loop mode. In this mode only a limited amount of sensors are used and the ecu is using a set of maps stored in it's memory vs using the 02 sensor etc.. to adjust the a/f ratios.
Once the ecu sees the coolant temp rise to a certain temp, it then goes into closed loop mode and uses all the sensors to adjust the engine parameters.
Also oil circulation is done probably within 5 seconds of the engine startup (probably sooner). If it actually took 15-30 seconds for the engine to see complete oil circulation, the engine would most likely be experiencing oil starvation damage.
Other than that, great post.
You're right, I should have also qualified my response by stating that the 15-30 seconds is for extremely cold temps, where the oil needs to thin out just a little bit before one goes racing off into the world. Thanks for catching this!
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