Engine Breaking?

saitrix said:
I just use the engine braking that I have in the gear I'm already in. I also use my gears for hills so I don't have to ride my brakes.
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Correct, you have selected a gear appropriate to the hazard.

saitrix said:
TheOtherPhil, Damn I couldn't remember IPSGA, then again I'm useless for remembering things like that. :o
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Unfortunately, this is a big part of my job....I HAVE to know it :)
 
I think some people are looking at engine braking in different terms. Its one thing backing off the throttle and leaving your car in gear antil you are about to stop (I do this), its something completely different to use the gearbox to slow the car, banging a car down through the gears to "save the brakes" is pretty pointless and definately counter productive.

Also as the OP was asking for methods of saving fuel leaving the car in gear whilst stopping will save him pence and isn't really worth worrying about.
 
james.miller said:
if you were to switch the engine off rather than engine brake you wouldnt hear much else other than road noise and such
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If you switched my engine off at speed, you'd hear me swear a lot as the steering and servo brakes shut down too.:D
 
The petrol used at idle is neither here nor there - yes it does use some, and some people say on some cars it won't even use this when you keep your clutch up and have no throttle.

Who cares - it won't save you enough petrol to notice.

The thing that is costing you money is a cold engine and accelerating, you have a 3 mile journey so you can't do anything about the cold engine but the accelerating you can.

Don't accelerate fast, that uses more - build speed slowly. Get up earlier so you miss the traffic, this will mean less stop-starts, taking a route that is slightly further but has less stops on it will probably help so long as it isn't too much further.

My number one piece of advice to save petrol on a 3 mile journey to school though - walk you lazy sod :D
 
The brake servo will retain suction for some time after an engine has stopped turning, its only good for one application though. I dont suggest testing this!
 
The brake servo is run directly off the engine, so as long as that's turning it will function. Ignition or no ignition. No matter though, you can still brake without a servo... it just means you'll need to use both feet and your body weight!

Power steering however depends if you've got electric or hydraulic. Electric power steering will be turned off whenever the ignition is turned off. Hydraulic runs directly off the engine I think.
 
yup there is a PAS pump driven by a belt off the crank.

Not sure what cars have electric as standard? Nice system though.
 
I actually speeak from experience here.

My Bravo had an intermittant fault where it felt like the ignition circuit cut out when I changed gear. A soon as I took it out of gear the engine stopped, when I put it back in gear and lifted the clutch the engine bump started and came back to life.


The car did this 3 times within a week, and hasn't done it again for 6 years, and FIAT never found out what was wrong when I took it in.

I had no power steering, and no servos on the brakes, one hand on the wheel (I was changing gear on a round-a-bout, twice, and once on a 90 degree steep downhill left hander). And it made me swear as I struggled to steer, brake and try and get it in gear to bump it off again.

edit.
oh, Bravos have hydraulic PAS, (you can hear the fluid pump start just after you start up).
 
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I think electric PAS is used as a "cheaper option" by car manufacturers. So really you get it on the town cars. May be totally wrong though...
 
Lets put this one to bed. Virtualy all modern fuel injection systems will not inject fuel on the overrun i.e. when engine braking. This is not only to improve economy, but to reduce emmisions.

On my Civic, you can actualy feel a small, but annoying lurch as you put your foot back on the throttle as the ECU starts injecting fuel again. More modern cars usualy make the transition much smoother.

Having no fuel injected will not melt the pistons because...well, there is no fuel being burnt.

The engine will not stall because it is being turned over by the momentum of the car.

The car still idles with a closed throttle because most OEM fuel injection systems have an air bypass valve, otherwise known as an idle valve which lets a small amount of air bypass the throttle under ECU control.
 
Yup I can always tell when my car cuts the ignition because the gear knob jolts a little bit. Then if I touch the right pedal it'll jolt a little again when the ignition starts up again.
 
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NathanE said:
I think electric PAS is used as a "cheaper option" by car manufacturers. So really you get it on the town cars. May be totally wrong though...
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the new passat has it, and thats not really a town car

give me hydraulic PAS anyday, actually have feedback through the wheel :D
 
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