Owners Manual - Starting and Stopping the Engine
07-21-2014, 09:20 PM
#1
Track Day
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Owners Manual - Starting and Stopping the Engine
Was reading through the owners manual last night and came across a couple of things I don't understand.
Starting the Engine:
Do not let the engine idle to warm up.
Why not?
Stopping the Engine:
Do not stop engine immediately after hard
or extended driving. Keep engine running
at increased idle for about two minutes to
prevent excessive heat build-up before turning
off engine.
Does anyone do this?
I live in Central Texas. We can have weeks of 100+ degree heat.
Should I not be turning my car off immediately?
"at increased idle" - That should make the neighbors happy.
Also, my engine fan will kick on and off for about 30 minutes after I park if it is really hot outside. Normal?
Thanks in advance.
Starting the Engine:
Do not let the engine idle to warm up.
Why not?
Stopping the Engine:
Do not stop engine immediately after hard
or extended driving. Keep engine running
at increased idle for about two minutes to
prevent excessive heat build-up before turning
off engine.
Does anyone do this?
I live in Central Texas. We can have weeks of 100+ degree heat.
Should I not be turning my car off immediately?
"at increased idle" - That should make the neighbors happy.
Also, my engine fan will kick on and off for about 30 minutes after I park if it is really hot outside. Normal?
Thanks in advance.
07-21-2014, 10:20 PM
#2
Burning Brakes
I've never noticed that in the manual. I know that for turbo cars it's not a good idea to immediately stop the engine after spirited driving. Some people even run turbo timers to let the car idle a few minutes after the key is removed from the ignition. Never heard about any danger to N/A vehicles. I'll have to look into that.
07-21-2014, 10:27 PM
#3
Three Wheelin'
Start-up:
Start-up combustion on a cold engine gets a rich and sloppy fuel mixture from the electronic mgmnt system, and this is generally true in all cars. It's how modern cars with emissions systems and electronic management systems take care of business. It's better to drive and warm up the engine to get out of this sloppy mode ASAP. Idling let's this sloppy condition linger and linger, and it causes fouling of internal parts. Don't think the cats love it. Cold engines wear faster, too. Less time cold = less slop and less wear.
So, drive off to reduce the amount of time the engine is cold and running sloppy rich.
Cool down:
At idle (and even more-so at increased idle), coolant and oil will come down in temp AND you'll cool off the engine a little bit. A hard run followed by fast stop of engine = omg... really?! ... how do you expect the cooling system (which is oil and water/antifreeze) to cool off the heat sink you just created in the engine if you turn it off?!
Think about it. Heat something up to very hot... it's protected by a cooling system, but as soon as you heat it up, you disable the cooling system. Not good.
The oil clearly cools down at idle faster than when driving. That is easy to see.
.
Start-up combustion on a cold engine gets a rich and sloppy fuel mixture from the electronic mgmnt system, and this is generally true in all cars. It's how modern cars with emissions systems and electronic management systems take care of business. It's better to drive and warm up the engine to get out of this sloppy mode ASAP. Idling let's this sloppy condition linger and linger, and it causes fouling of internal parts. Don't think the cats love it. Cold engines wear faster, too. Less time cold = less slop and less wear.
So, drive off to reduce the amount of time the engine is cold and running sloppy rich.
Cool down:
At idle (and even more-so at increased idle), coolant and oil will come down in temp AND you'll cool off the engine a little bit. A hard run followed by fast stop of engine = omg... really?! ... how do you expect the cooling system (which is oil and water/antifreeze) to cool off the heat sink you just created in the engine if you turn it off?!
Think about it. Heat something up to very hot... it's protected by a cooling system, but as soon as you heat it up, you disable the cooling system. Not good.
The oil clearly cools down at idle faster than when driving. That is easy to see.
.
Last edited by Philster; 07-22-2014 at 08:24 AM.
07-21-2014, 10:38 PM
#4
Instructor
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Start-up: Start-up combustion on a cold engine gets a rich and sloppy fuel mixture from the electronic mgmnt system, and this is generally true in all cars. It's how modern cars with emissions systems and electronic management systems take care of business. It's better to drive and warm up the engine to get out of this sloppy mode ASAP. Idling let's this sloppy condition linger and linger, and it causes fouling of internal parts. Don't think the cats love it. Cold engines wear faster, too. Less time cold = less slop and less wear. So, drive off to reduce the amount of time the engine is cold and running sloppy rich. Cool down: At idle (and even more-so at increased idle), coolant and oil will come down in temp AND you'll cool off the engine a little bit. A hard run followed by fast stop of engine = omg... really?! ... how do you expect the cooling system (which is oil and water/antifreeze) to cool off the heat sink you just created in the engine if you turn it off?! Think about it. Heat something up to very hot... it's protected by a cooling system, but at soon as you heat it up, you disable the cooling system. Not good. The oil clearly cools down at idle faster than when driving. That is easy to see. .
I start mine up let the idle drop let the oil gauge go up one notch and drive off. Been doing it 8yrs no problems. As for shutting down. I shut it down there is no turbo for the oil to cool off the turbos or anything. If its hot the fan will kick in and cool it down. IMO
07-21-2014, 10:51 PM
#5
Track Day
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Philster,
Great info! Thanks!
Start Up: makes complete sense now.
Cool Down: I was more worried about the heat down here in Texas than "spirited driving". There are times when oil temp shows 245 degrees. If it is that hot, should I let it idle in the driveway before shutting down?
Note: I have never seen the water temp move from 175.
I have only owned her for 3 weeks. Want to make sure I am treating her right!
Great info! Thanks!
Start Up: makes complete sense now.
Cool Down: I was more worried about the heat down here in Texas than "spirited driving". There are times when oil temp shows 245 degrees. If it is that hot, should I let it idle in the driveway before shutting down?
Note: I have never seen the water temp move from 175.
I have only owned her for 3 weeks. Want to make sure I am treating her right!
07-22-2014, 12:06 AM
#6
Three Wheelin'
The water temp gauge is bogus. It goes to 175 no matter what the actual temp after the initial warm up. It's a glorified idiot light.
Carrera997re: That's nice. To increase the likelihood of having a problem (not guarantee it), please do continue.
Again, these are 'best practices' and serve to mitigate long-term issues that might arise for some engines, which operate in countless conditions at the hands of assorted drivers, fuels, atmospheric pressures, temperatures, etc, etc.
Both practices recommended in the manual make complete sense. Sure, your engine won't blow up, but these are little things you can do to prevent problems from slowly creeping in. After many miles, maybe you'll have a bit less wear, more compression, less carbon, longer life for emissions systems, plugs, etc.
Cheers.
Carrera997re: That's nice. To increase the likelihood of having a problem (not guarantee it), please do continue.
Again, these are 'best practices' and serve to mitigate long-term issues that might arise for some engines, which operate in countless conditions at the hands of assorted drivers, fuels, atmospheric pressures, temperatures, etc, etc.
Both practices recommended in the manual make complete sense. Sure, your engine won't blow up, but these are little things you can do to prevent problems from slowly creeping in. After many miles, maybe you'll have a bit less wear, more compression, less carbon, longer life for emissions systems, plugs, etc.
Cheers.
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07-22-2014, 04:08 AM
#8
Rennlist Member
I generally will drive off in the morning, maybe idle for 20 or 30 seconds before backing out, unless I'm particularly dreading work- then I will let it idle down before I leave.
After work, I will usually idle till the RPM's drop before taking off. This as my "let it go" moment before getting on the road.
After a spirited run up in the mountains or along the coast I will generally let her idle for about 90 seconds when I get home, usually I just let whatever song is on the stereo play out once I'm in the garage.
Typically the last few miles coming home are my "cool down" anyway. I keep the revs and speed pretty low, definitely around 2k and under 25 mph in my neighborhood always. That's the "No Wake Zone."
After work, I will usually idle till the RPM's drop before taking off. This as my "let it go" moment before getting on the road.
After a spirited run up in the mountains or along the coast I will generally let her idle for about 90 seconds when I get home, usually I just let whatever song is on the stereo play out once I'm in the garage.
Typically the last few miles coming home are my "cool down" anyway. I keep the revs and speed pretty low, definitely around 2k and under 25 mph in my neighborhood always. That's the "No Wake Zone."
07-22-2014, 09:50 AM
#10
Burning Brakes
Interesting info. Thanks Philster.
07-22-2014, 10:00 AM
#11
Rennlist Member
I always drive off immediately at start up but do not exceed 3k rpm until water temp comes up and then don't exceed 4k rpm (book answer) until oil temp moving up. On shutdown, I try not to drive it too hard the last minute or two before planned shutdown, and if I was running it hard, I idle for 30 seconds to a minute and open the rear spoiler manually (with the switch) to aid in cooling. The spoiler will automatically lift when a high engine bay temp is raised but I always raise it just to aid the thermo process. Funny my wife's '08 VW V8 Touareg has an electric pump that circulates the water for a couple minutes after shutdown.
07-22-2014, 12:20 PM
#12
Rennlist Member
Start-up:
Start-up combustion on a cold engine gets a rich and sloppy fuel mixture from the electronic mgmnt system, and this is generally true in all cars. It's how modern cars with emissions systems and electronic management systems take care of business. It's better to drive and warm up the engine to get out of this sloppy mode ASAP. Idling let's this sloppy condition linger and linger, and it causes fouling of internal parts. Don't think the cats love it. Cold engines wear faster, too. Less time cold = less slop and less wear.
So, drive off to reduce the amount of time the engine is cold and running sloppy rich.
Cool down:
At idle (and even more-so at increased idle), coolant and oil will come down in temp AND you'll cool off the engine a little bit. A hard run followed by fast stop of engine = omg... really?! ... how do you expect the cooling system (which is oil and water/antifreeze) to cool off the heat sink you just created in the engine if you turn it off?!
Think about it. Heat something up to very hot... it's protected by a cooling system, but as soon as you heat it up, you disable the cooling system. Not good.
The oil clearly cools down at idle faster than when driving. That is easy to see.
.
Start-up combustion on a cold engine gets a rich and sloppy fuel mixture from the electronic mgmnt system, and this is generally true in all cars. It's how modern cars with emissions systems and electronic management systems take care of business. It's better to drive and warm up the engine to get out of this sloppy mode ASAP. Idling let's this sloppy condition linger and linger, and it causes fouling of internal parts. Don't think the cats love it. Cold engines wear faster, too. Less time cold = less slop and less wear.
So, drive off to reduce the amount of time the engine is cold and running sloppy rich.
Cool down:
At idle (and even more-so at increased idle), coolant and oil will come down in temp AND you'll cool off the engine a little bit. A hard run followed by fast stop of engine = omg... really?! ... how do you expect the cooling system (which is oil and water/antifreeze) to cool off the heat sink you just created in the engine if you turn it off?!
Think about it. Heat something up to very hot... it's protected by a cooling system, but as soon as you heat it up, you disable the cooling system. Not good.
The oil clearly cools down at idle faster than when driving. That is easy to see.
.
07-22-2014, 12:58 PM
#13
I'm in Texas also. I start it and drive off. I only worry about letting it warm up before hitting the gas in the winter. Although I do avoid hitting the rev limiter before everything is up to temp. I rarely drive below 3000 rpm in any gear, unless in traffic, etc, and lugging the motor is not good for it, hot or cold.
My neighborhood is full of speed bumps, so the last few minutes are always at very low speed so I don't worry about idling before shutting it down. Same applies to just about anywhere I go, there is that few minutes of negotiating traffic or slow streets before stopping.
My neighborhood is full of speed bumps, so the last few minutes are always at very low speed so I don't worry about idling before shutting it down. Same applies to just about anywhere I go, there is that few minutes of negotiating traffic or slow streets before stopping.
07-22-2014, 02:21 PM
#14
Three Wheelin'
High idle is a few hundred RPM above the regular idle. In older cars with belt driven fans it was twice the RPM. in modern cars, it is somewhere below 1,000 RPM.
It probably can be calculated to work out to an engine speed that is high enough to speed cooling but not so high as to maintain or add to the heat sink.
It really matters if you JUST ran hard and hot. Just a way of saying, "Don't disable the cooling system right after you just created a massive heat sink!"
It probably can be calculated to work out to an engine speed that is high enough to speed cooling but not so high as to maintain or add to the heat sink.
It really matters if you JUST ran hard and hot. Just a way of saying, "Don't disable the cooling system right after you just created a massive heat sink!"
