Q: when shifting into neutral... clutch?

[ilikerice]

Ok, wait.. I have seen this DFCO in many other threads and was determined that if the car is not using fuel, then the motor does not run, that it will cut off.. if my fuel pump goes out, my engine will stop running. There is still fuel to the motor reguardless. Engine will alway be around 800 rpm's. Only thing I have seen that utilizes this is the Synergy drive hybrids toyota uses. Even when the engine is off completly. You will still feel the shutter when the motor kicks in to charge the battery.

I still see no difference in coasting in neutral or leaving it in gear DFCO, when I leave it in gear I am engine braking. I dont believe fuel is completly cut off.. maybe minimized, but not cut off.

[Kioshi]

Originally Posted by why?

No idea how anyone got the idea of clutchless shifting out of the ops post. It is something that should never be done outside of a semi.



not it wasn't, it was wrong. Neutral will get better gas mileage in most situations, leaving the car in gear can get better gas mileage in certain unusual situations, like going down a very steep hill, or when you want to stop anyways. Other than those two situations coasting in neutral will get better gas mileage.

Neutral does not get you better mileage going down a hill or just coasting....you still have to rev match to put into gear again...and that blimp of the throttle isn't saving you more gas then simply leaving it in gear and shifting higher w/o blimping the throttle.

3 of us were making our way back down lots of mountains this previous weekend....we gained more mpg being in gear then in neutral. Plus.....you're just wearing out your brakes being in neutral coasting down....

[ChitownY@Ris]

Sort of off topic, but it's in reference to the tranny nontheless.. In my automatic sedan I frequently use gear 2 or 3 while driving. I find it gives me more low end torque to merge or make passes, than it does if I leave it in drive and have to floor the pedal just to do the same. So is downshifting the auto tranny going to torch it?? Btw I never redline it, which I think any amatuer knows is bad on the tranny. I also noticed I benefit from the engine braking by throwing down to 2 when nearing a light or stop sign.

[Sparcoboy]

Originally Posted by why?

not it wasn't, it was wrong. Neutral will get better gas mileage in most situations, leaving the car in gear can get better gas mileage in certain unusual situations, like going down a very steep hill, or when you want to stop anyways. Other than those two situations coasting in neutral will get better gas mileage.

No you're wrong, when your in neutral, or depressed clutch, the car has to idle the engine, using fuel. When left in gear, clutch engaged, the car will drive the engine so no fuel is needed to keep the engine above idle.

[ilikerice]

going back to what I said earlier.. the engine is still running if you are still in gear decelerating. The engine never cuts fuel completely or it will shut off.. Next time your driving, turn the key off while rolling. You will notice it when its off, and when you the motor starts back up again. The transmission is only slowing the speed of the crankshaft while clutch is engaged. Engine still needs fuel to stay alive and move after pressing the gas soon after. Engines never cut off unless its a Synergy Drive hybrid.

Please someone show me actual real time data on fuel volume while driving. Easily done if you have a TechStream laptop from a dealer. fyi

[Betrivent]

A quick read-around has shown that DFCO, in Hondas at least, causes the injectors to stop until 1000 RPM, when they come back on.

[why?]

Originally Posted by Sparcoboy

No you're wrong, when your in neutral, or depressed clutch, the car has to idle the engine, using fuel. When left in gear, clutch engaged, the car will drive the engine so no fuel is needed to keep the engine above idle.

actual testing done by hyper milers proves that you can coast much further in neutral than you can in DFCO, and the penny's worth of gas the Yaris uses per mile doesn't change that. Testing has proven that DFCO uses more gas than neutral coasting, because DFCO makes you press the accelerator more. You can easily test this yourself, speed up to 30 mph, reset your odometer, and coast to a stop. Then do the same for DFCO.

Originally Posted by ilikerice

going back to what I said earlier.. the engine is still running if you are still in gear decelerating. The engine never cuts fuel completely or it will shut off.. Next time your driving, turn the key off while rolling. You will notice it when its off, and when you the motor starts back up again. The transmission is only slowing the speed of the crankshaft while clutch is engaged. Engine still needs fuel to stay alive and move after pressing the gas soon after. Engines never cut off unless its a Synergy Drive hybrid.

Please someone show me actual real time data on fuel volume while driving. Easily done if you have a TechStream laptop from a dealer. fyi

DFCO cuts all fuel above 1500 rpms. The actual technical data is in the FE forums somewhere, but anyone with a scanguage or one of the other obd2 guages can show you as well. The air circulating through it can easily keep it going above that.

[curtmaxwall]

Originally Posted by yarisugi

Throwing out this question to all of you. Let's say I'm in a gear (3rd,4th,5th, etc.) and I decide to shift into neutral to save some gas and coast. As a habit, I always press the clutch before I shift into neutral. Do I need to press in the clutch or can I just shift it out of the gear straight into neutral?

Definitely, you should depress the clutch before changing the gear. It will not only make your gear changing smoother but also saves your gear tooth from being damaged. When clutch is in engage position with the engine, the speed of the clutch is almost same as that of the engine. If you are trying to move the gear at more that 6000 rpm, it might be happens that your gear tooth is damaged and so your whole transmission system. so its always better to press the clutch before changing the gear.

[ilikerice]

Last 4 posts.. makes more sense. Topic went way off course. I stand corrected as I have looked into what Betrivent and WHY? either way, I dont feel either one is better then the other, depending on the situation your in

[why?]

Originally Posted by PK198105

ok this topic has been beat into eternity. 1. AS A SAFETY CONCERN NEVER COAST IN NEUTRAL (what happens when you need to accelerate quickly and you forget you are in neutral...)2. COASTING AND ENGINE BRAKING 2 different things.

you're kidding right? That is like saying."never point the barrel of a loaded gun in your mouth and pull the trigger because you might die."

It is a manual transmission. If you don't know how to shift you shouldn't be driving one.

[Idahotom]

I have several sections on my most traveled routes where I use BOTH DFCO AND coasting in nuetral. It's not an either or thing to me. I like seeing the Scan Gauge reading 999999 (meaning zero fuel flow for those without one) when DFCO'ing, it's also fun to see the coasting mileage in the 400's. It really all depends of course on the speed needed and the grade of the road, obviously.

I do both without impeding any traffic, or reaching unsafe or illegal speeds. Some of the grades are best negotiated with DFCO techniques, others are better suited for free coasting, simple as that. I don't "forget that I am in nuetral", ever.

My favorite coast is an off ramp from I-15, with a smooth merge onto a 4 lane road then a further 1/4 mile coast to the turn in to my favorite grocery store, which has a large sloped parking lot. I routinely put her in nuetral while still on the interstate, I take the exit at the posted speed, and in general make the entire approach to the market without deviating from normal traffic flow. By the time I'm in the parking lot I am going the suggested 5 or 10 MPH after turning off the 35 mph 4 lane, where I was also going 35. I see no danger in doing this, best of all it's REAL easy on the clutch!

[Betrivent]

Admittedly, there's this huge hill on Hwy 99 I like to coast down.. And not being a 30 ton truck, I feel comfortable doing it and not endangering anybody.

[yarisugi]

Wow, all this from a simple question. Thanks for your replies. Just wanted to know whether you use the clutch when shifting OUT of a gear and into neutral. Wasn't really concerned about clutchless shifting but thanks anyway. I'll stick to pressing the clutch in when I shift.

[why?]

Originally Posted by PK198105

lol ok...keep doing what you're doing . ill be waiting for your rear end pics. You're not suppose to use neutral besides coming to a full stop. And your quote doesn't mean anything because you still have people die from accidental discharges.....

so now it would be my fault if i was rear ended? What insane hellish world do you live in? Last time I checked the only car I can control is my own, I don't have any way to control any other cars. You statement just has zero logic.

Originally Posted by Idahotom

I have several sections on my most traveled routes where I use BOTH DFCO AND coasting in nuetral. It's not an either or thing to me. I like seeing the Scan Gauge reading 999999 (meaning zero fuel flow for those without one) when DFCO'ing, it's also fun to see the coasting mileage in the 400's. It really all depends of course on the speed needed and the grade of the road, obviously.

I do both without impeding any traffic, or reaching unsafe or illegal speeds. Some of the grades are best negotiated with DFCO techniques, others are better suited for free coasting, simple as that. I don't "forget that I am in nuetral", ever.

My favorite coast is an off ramp from I-15, with a smooth merge onto a 4 lane road then a further 1/4 mile coast to the turn in to my favorite grocery store, which has a large sloped parking lot. I routinely put her in nuetral while still on the interstate, I take the exit at the posted speed, and in general make the entire approach to the market without deviating from normal traffic flow. By the time I'm in the parking lot I am going the suggested 5 or 10 MPH after turning off the 35 mph 4 lane, where I was also going 35. I see no danger in doing this, best of all it's REAL easy on the clutch!

exactly.