# what does engine high idle mean?

What does engine high idle mean?

Thank you!
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Commented:
It's the opposite of the other question you asked,

The engine has a shaft in the middle that spins so many revolutions per minute (RPM).     When you press the gas pedal, you cause the RPM to go faster, which accelerates the car.    When you are sitting at a stop light,   you are not pressing the gas, but you don't want the engine to stop, because you want to be ready to go on a green light,  so the car keeps the RPM at a minimum to keep the car ready to go.    That RPM number (600-1000rpm) when you are sitting still, with no foot on the gas pedal is your "idle".

If the Idle is too high, then the car is experiencing unneeded wear & tear, and you're wasting fuel.

Further info,

http://en.wikipedia.org/wiki/Idle_speed
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Author Commented:
so does high idle mean that RPM is greater than 600-1000 RPM when foot is off the gas pedal.

And does low idle mean that RPM is lower than 600-1000 RPM when foot is off the gas pedal?
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Commented:
Yes, exactly.

There is an optimum idle when the foot is not on the pedal.

This optimum varies depending on the car.    600-1000rpm is an average optimum idle.
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Commented:
If you are talking about machinery (which I think you are) quote from your other question:
http://www.experts-exchange.com/Other/Automotive/Q_28010676.html
"I meant Low Idle"
Then the correct answer is that:
The machines engine will run at a "LOW IDLE" speed when the machinery is not engaged for use and will go into a "HIGH IDLE" speed when engaged to be used and thus, ready to accelerate when more power is required by the machinery.

" so does high idle mean that RPM is greater than 600-1000 RPM when foot is off the gas pedal.
And does low idle mean that RPM is lower than 600-1000 RPM when foot is off the gas pedal? "

If the engine is diesel then the answer is no... as diesel engines idle at much lower speeds depending on the engine the idle could be as low as 250 RPM
You will need to look up the specifications for the particular engine.

If my answer is better for your question then please click the "Request Attiontion" tab for a moderator to help.
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Author Commented:
Yes, I'm talking about Asphalt Paver Machines.   When you say machine engine, do you mean that machine engine is powering machine functions.  And is there another engine that moves the tractor or vehicle.

Thank you so much for responding after points were assigned.
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Commented:
"When you say machine engine, do you mean that machine engine is powering machine functions."

Yes on Asphalt Paver Machines one engine drives both the paver along the road and its paving functions or pavement laying operations.

It seems obvious that you have selected answers for both this question and your other question : http://www.experts-exchange.com/Other/Automotive/Q_28010676.html
that are intended for cars which do not suit your questions about Asphalt Paver Machines.