Engine Braking Vs. Idle Coasting
4th Gear Member
Joined: Mar 2004
Posts: 1,090
From: Az
RE: Engine Braking Vs. Idle Coasting
ThatIS interesting..I am still carbed myself and found you can alo save gason the upshifts. I shift by 2k and skip 3rd. I noticed quite a difference doing it ths way but can't go too long keeping my foot out of it, loosing any gains.
6th Gear Member
Joined: Nov 2005
Posts: 8,467
From: Rochester, NY
RE: Engine Braking Vs. Idle Coasting
I'm pretty sure it's better to leave the car in gear cause when you're engine braking the air/fuel mixture should be more lean than at idle. Either way putting the car in neutral and coasting and braking to a stop is incorrect, and is also using more brakes than necessary.
Thread Starter
Joined: May 2008
Posts: 37
From:
RE: Engine Braking Vs. Idle Coasting
ORIGINAL: blstoff
yes , by coasting I mean leaving it in gear . here is a little more about coasting fuel shutoff . there are certain criteria that have to be met before the ecm will enter coasting fuel shutoff . this is how its setup from ford ,
minimumvehicle speedto enter= 25mph
minimum rpm to enter= 950
time at closed throttle to enter = 4
rpm below to turn fuel on = 800
vehicle speedbelow to turn fuel on = 3
minimum coolant temp to enter = 160
there's a few more parameters but you can see whats happening w/ these . so , say your going 25mph+ . you have to be off the accelerator for 4 seconds & then the fuel injectors will shut off.when you press in the clutch pedal & the rpm's drop to 800 the injectorsare turning back on which is sooner than if you had just left it in gear . well , in your case I would say you are probably putting it in neutral before the injectors shut off .
yes , by coasting I mean leaving it in gear . here is a little more about coasting fuel shutoff . there are certain criteria that have to be met before the ecm will enter coasting fuel shutoff . this is how its setup from ford ,
minimumvehicle speedto enter= 25mph
minimum rpm to enter= 950
time at closed throttle to enter = 4
rpm below to turn fuel on = 800
vehicle speedbelow to turn fuel on = 3
minimum coolant temp to enter = 160
there's a few more parameters but you can see whats happening w/ these . so , say your going 25mph+ . you have to be off the accelerator for 4 seconds & then the fuel injectors will shut off.when you press in the clutch pedal & the rpm's drop to 800 the injectorsare turning back on which is sooner than if you had just left it in gear . well , in your case I would say you are probably putting it in neutral before the injectors shut off .
Impressed by MustangForums members as always!
2nd Gear Member
Joined: Aug 2006
Posts: 492
From: MD
RE: Engine Braking Vs. Idle Coasting
ORIGINAL: strykrpixel
Thanks blstoff for that detailed reply... that certainly answers my question and goes above and beyond. I appreciate the time it must've taken to find that data and it's very useful.
Impressed by MustangForums members as always!
ORIGINAL: blstoff
yes , by coasting I mean leaving it in gear . here is a little more about coasting fuel shutoff . there are certain criteria that have to be met before the ecm will enter coasting fuel shutoff . this is how its setup from ford ,
minimumvehicle speedto enter= 25mph
minimum rpm to enter= 950
time at closed throttle to enter = 4
rpm below to turn fuel on = 800
vehicle speedbelow to turn fuel on = 3
minimum coolant temp to enter = 160
there's a few more parameters but you can see whats happening w/ these . so , say your going 25mph+ . you have to be off the accelerator for 4 seconds & then the fuel injectors will shut off.when you press in the clutch pedal & the rpm's drop to 800 the injectorsare turning back on which is sooner than if you had just left it in gear . well , in your case I would say you are probably putting it in neutral before the injectors shut off .
yes , by coasting I mean leaving it in gear . here is a little more about coasting fuel shutoff . there are certain criteria that have to be met before the ecm will enter coasting fuel shutoff . this is how its setup from ford ,
minimumvehicle speedto enter= 25mph
minimum rpm to enter= 950
time at closed throttle to enter = 4
rpm below to turn fuel on = 800
vehicle speedbelow to turn fuel on = 3
minimum coolant temp to enter = 160
there's a few more parameters but you can see whats happening w/ these . so , say your going 25mph+ . you have to be off the accelerator for 4 seconds & then the fuel injectors will shut off.when you press in the clutch pedal & the rpm's drop to 800 the injectorsare turning back on which is sooner than if you had just left it in gear . well , in your case I would say you are probably putting it in neutral before the injectors shut off .
Impressed by MustangForums members as always!
3rd Gear Member
Joined: Apr 2008
Posts: 939
From:
RE: Engine Braking Vs. Idle Coasting
Well, all that theory is pretty interesting. I learned some stuff. BUT, does it answer the question? IMO, no really. Theory is good, but without testing, it's just theory.
So, time to test the theory. Commute for one week using engine braking. See what your average gas mileage is. Then commute for one week coasting as much as possible. Which one saves more gas.
I don't know the answer. But I'm keen to find out.
So, time to test the theory. Commute for one week using engine braking. See what your average gas mileage is. Then commute for one week coasting as much as possible. Which one saves more gas.
I don't know the answer. But I'm keen to find out.
4th Gear Member
Joined: Jan 2007
Posts: 1,999
From:
RE: Engine Braking Vs. Idle Coasting
Both methods carry their own advantages and this only applies to cars new enough to carry the shut off feature.
I'll say how you apply each method will determine which is the best method.
If you engine brake, you are indeed slowing the car. This is not the most efficient way of driving. Coasting in neutral may be using more fuel but think of this, the car will coast longer/further distance.
This is similar to which is a better rear brake. Rear brakes have little to offer. Just like decellerating. One may improve your mileage 0.5%, the other 0.6%. Most of your mileage improvements will be made during acceleration and cruising speed.
I'll say how you apply each method will determine which is the best method.
If you engine brake, you are indeed slowing the car. This is not the most efficient way of driving. Coasting in neutral may be using more fuel but think of this, the car will coast longer/further distance.
This is similar to which is a better rear brake. Rear brakes have little to offer. Just like decellerating. One may improve your mileage 0.5%, the other 0.6%. Most of your mileage improvements will be made during acceleration and cruising speed.
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