Engine compression

[Stickman42]

Newer cars have the auto stop/start feature when idling. It's been said on this forum that compression is not lost during this stoppage, unlike when the engine is turned completely off. I'm curious about the difference. Is it that it takes time for the compression to leak past the piston rings? I am just looking to gain a better understanding of this type of system. My internet research has yielded at least several different explanations/opinions.

 

[pippip]

Yeh there are few different systems. Mazda actually stops the engine with fuel in the engine and
​uses the spark to restart it rather than the starter motor, mainly cause its faster.

 

[Alois Senefelder]

Hello stickman,

Re- your question about "Engine Compression" I suggest you search, The Society of Automobile Engingeers web site !

 

[HafProp]

I can't stand that when you set the cruise control & you are 10 car lengths behind a vehicle it automatically slows down 10 mph!
A worthless feature!

 

[Stickman42]

Hello stickman,

Re- your question about "Engine Compression" I suggest you search, The Society of Automobile Engingeers web site !

Thanks Alois, but it looks like the deep answers come at a price there. I prefer forum banter over heavy reading for this subject too.

Anyhow, for those who care to contribute to my quest for understanding, I'm all ears. Let me start with this:

When the stop/start (S/S) system brings the engine to a halt, what restarts it? Is it merely first firing the spark plug of the cylinder in its compression stroke? Or does the starter kick in?

 

[gregbatch]

I can't stand that when you set the cruise control & you are 10 car lengths behind a vehicle it automatically slows down 10 mph!
A worthless feature!

That's why they now have adaptive cruise control.

 

[pdan]

Adaptive cruise control is pretty cool. I think cruise control should be mandatory on highways. I'm curious if my Chevy has that spark to start feature or uses the starter. I think I'll Google it.
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