blipping the throttle before shutdown?
 

just thought i'd ask...

why do most people blip the throttle before shutting down the engine?

be it gas, diesel, carbureted and injected

I think the purpose of this, in carbed motors with hot cams, is because they idle very rich. So by turning the ignition off at a high rev, they start more easily. Otherwise, if shut off at idle, they're flooded. That's how it was explained to me years back when I asked the same question.

cool! thanks geoff.

i knew it had benefits for carbed engines, i didn't understand why people do the same thing when most new cars nowadays are computer controlled and injected. force of habit i guess

no benefit
 

now. maybe back then when people had carbs. i never did it even back then. seemed like folks just liked to hear it rev up before shutting it off to me.

tom w

some even say that the extra blip gives the battery an extra charge for the next startup, any truth to this?

it would be
 

true but the extra would only occur if the battery is already low and the regulator is calling for charge. which is unlikely unless you just started up.

tom w

The medical term for it is called DOHS.





Which is Dukes of Hazzord Syndome !! :P

Theres one school of thought that says that blipping the throttle as you switch off will just leave unburnt fuel in the cylinders..which will eventually wash down into the crankcase.

Might be a good idea to build up some revs and switch off the ignition say for the last five or six trips just before doing an oil-change.......hopefully the fuel draining into the block would get some crud off the rings on their way down??

Thoughts on this ??

Anil

With CIS or carburetor, you probably can de-oil the cylinders to some extent this way, by killing the ignition while fuel is still coming into the engine. Sounds like a great way to increase wear on startup, especially if you are going to drain the oil and it will take several seconds to develop oil pressure when you restart.

With EFI or diesel, the fuel will cut off while the engine is turning, so I don't see any effect, except for possible harm to a turbocharger if you get it going fast and then turn off its oil supply.

klink had it right
 

except for the last word which i would sub a four letterword for beginning with s and ending w t.

as noted above no good can come from it.

tom w

This is definitely a mortal sin for any motor with a turbocharger.
 

And yet, somehow, 48 years after I got my first driver's license, I still do it without thinking now and then.

It is Mandantory to do this on a Harley ..... I can elaborate for hours on that statement but will let the Chips Fall where the may...lol