My FC Getting Better With Low RPM

[Jazz]

To my understanding, as long as u depress ur accelerator, the fuel will be injected. BUT if u dont press it, no fuel will be injected loh..

thats y, when i go downslope, i dont depress the accelerator... let gravity do the work for me + i save fuel aka $$$

Ha ha ha ...... wrong !! Don't tell me when your engine on idle, no fuel is being injected ? So your engine block is vacuum if you do not step on your accelerator and let it free run, put your gear to D mode and just let it roll. 

[SoL]

When idle, yes, fuel is consumed.

However, when in gear, like D, something called deceleration fuel-cutoff (DFCO) takes place. From what I observed on my 4AT, at speeds above 45, when you lift your leg off accelerator, the fuel injection cuts-off. Instead, the engine is kept running by momentum from the wheels.

Fuel injection continues when your speed is below 45 in D, when the engine rpm isn't enough to keep the engine running. So normally when stopping, i'd go from D to OD-OFF to 2, then stop. Helps save some fuel.

This is not a very good way to go downslope unless you're planning to stop or you're going too fast, as engine braking is still not as good as coasting in Neutral.

This feature has been in cars since 92, if i'm not wrong.

[Toalson]

Fuel is being consumed even if you dont step on the acceletor. As long as engine running fuel is consumed but at what rate will depend on rpm.
Didnt one of the fuel saving techniques discourages idling? 

[ralliart99]

Yes bro but these 2 points are only part of my secret of good FC......pressing hard to reach cruising speed at expressway have to depend on road condition like if its up hill slope i would advise to stay at 2krpm and if its flat or even better if down slope i will press harder to take advantage of gravity to pick up my speed

For cruising on highway i do not stay at 90km/hr constanly as i adapt my speed according to gravity.....example if i know that i am approaching a uphil slope i will step on the throttle slightly harder to reach maybe 100km/hr to build up my car kinetic energy to go up the hill but i will still stay at highest gear and not press that much to let gear shift to lower range as that would mean that our engine is wasting fuel to fight with gravity and when i reach the top of the slope i will than let the car glide down it to reach speeds up to 110km/hr and very slowly gently ease the throttle to let it reach back to 80-90km/hr

For normal road actually quite simple to get good FC if we all follow the logic of 'The less u brake the better ur Fc' & 'The moment u release the throttle no fuel is consume untill ur speed fall untill about 30km/hr' soo we try if we can to look further to anticipate traffic and lights and let the engine do the braking and not the brakes to save on the fuel and brake pads

yo guys, did something similiar to the bro's method above,
A) i reach my optimum speed asap and maintain that as long as i could. i keep a distance with the car in front so i do not need to depress the brake in case the car slows down. i just need to release the accelerator.
B) as for main roads, i pickup at rpm to 2 max and maintain speed. try not to have sudden surge of speed

i reach my half way mark and clocked a total distance of 310
i was surprised too at the reading, even double check to see if the reading is correct 

btw, i'm on 16" 205/50. my previous readings before this experiment is around 13 to 14km/l best. hope can better this :)

on 60 expressway and 40 main roads 

[SoL]

Fuel is being consumed even if you dont step on the acceletor. As long as engine running fuel is consumed but at what rate will depend on rpm.
Didnt one of the fuel saving techniques discourages idling? 

Yes, idling is discouraged because idling occurs when you stop, which means engine rpm is not enough to keep engine running without using fuel.

At high speeds like 45 and above(for me), when u lift your leg off accelerator, fuel injection stop, thus engine braking. If you don't believe, try this:

1.Get your speed up to 70-80km/h.

2.Release accelerator. Your car speed should slow down very fast. This is engine braking, and no fuel is being consumed at this point.

3.At around 45km/h, you should feel a jerk as fuel injection resumes and your car is free wheeling(less engine braking).

This is tried and tested on 4AT. For CVT, your mileage may vary.

[Ying]

When idle, yes, fuel is consumed.

However, when in gear, like D, something called deceleration fuel-cutoff (DFCO) takes place. From what I observed on my 4AT, at speeds above 45, when you lift your leg off accelerator, the fuel injection cuts-off. Instead, the engine is kept running by momentum from the wheels.

Fuel injection continues when your speed is below 45 in D, when the engine rpm isn't enough to keep the engine running. So normally when stopping, i'd go from D to OD-OFF to 2, then stop. Helps save some fuel.

This is not a very good way to go downslope unless you're planning to stop or you're going too fast, as engine braking is still not as good as coasting in Neutral.

This feature has been in cars since 92, if i'm not wrong.

Yes, while in D, once I release my right foot, I believe the controller cuts-off(or should I say greatly reduce) fuel to helps slow down the car from higher speed to ~30km/h. Then it will inject some fuel even I dont touch the pedal.

while idle, car speed is below 30km/h right? so the controller will inject fuel even you dont touch the pedal.

[Ying]

Yes, idling is discouraged because idling occurs when you stop, which means engine rpm is not enough to keep engine running without using fuel.

At high speeds like 45 and above(for me), when u lift your leg off accelerator, fuel injection stop, thus engine braking. If you don't believe, try this:

1.Get your speed up to 70-80km/h.

2.Release accelerator. Your car speed should slow down very fast. This is engine braking, and no fuel is being consumed at this point.

3.At around 45km/h, you should feel a jerk as fuel injection resumes and your car is free wheeling(less engine braking).

This is tried and tested on 4AT. For CVT, your mileage may vary.

yeap, the jerk happen ~30km/h+ for my CVT.

[SoL]

Yes, while in D, once I release my right foot, I believe the controller cuts-off(or should I say greatly reduce) fuel to helps slow down the car from higher speed to ~30km/h. Then it will inject some fuel even I dont touch the pedal.

while idle, car speed is below 30km/h right? so the controller will inject fuel even you dont touch the pedal.

Yes, thats right. But its not greatly reduce, its cut-off.

[Jazz]

Yes, thats right. But its not greatly reduce, its cut-off.

It not totally cut off, once your engine is burnt off fuel, the ECU will still tell the fuel injector to inject fuel to maintain idle speed, else if you idle too long, your engine will stalled if you do not depress your accelerator ?

[SoL]

Im sorry, im a bit confused.

So you are trying to say fuel is not cutoff when idling? Yes, thats right, because idling happens when u stop, and rpm is not high enough, thus fuel is injected.

[fri13th]

yo guys, did something similiar to the bro's method above,
A) i reach my optimum speed asap and maintain that as long as i could. i keep a distance with the car in front so i do not need to depress the brake in case the car slows down. i just need to release the accelerator.
B) as for main roads, i pickup at rpm to 2 max and maintain speed. try not to have sudden surge of speed

i reach my half way mark and clocked a total distance of 310
i was surprised too at the reading, even double check to see if the reading is correct 

btw, i'm on 16" 205/50. my previous readings before this experiment is around 13 to 14km/l best. hope can better this :)

on 60 expressway and 40 main roads 

Happy that u guys benefitted from the info that i posted

U guys dun argue with the fuel got cut or no cut lar....all started becos of me but as long as it saves fuel and money by using engine brake rather than our brakes no need to argue got cut no cut lar.....win liao also no trophy

[hammer99]

I try this technique,

I realised PIE and BKE or KJE, a lot of slope, whenever, there is a downward slope, I free my gear to N, gain 10 to 20km/hr, on downward driving. If you travel often from North to West often, you know what I meant. Then keep speed around 65 to 75km to achieve low rpm (1.2 to 1.5). Pick up slowly,especially 1st gear, at traffic junction. Shift to N at Stop position.

Results : 630KM cover with 35L or 410 with 22L of petrol.

Just ondering, this shifting gear from N to D, will it damage or wear out the gear faster ?

[fri13th]

hi bro, u should minus 2~3 l to calculate the correct FC mah..rite?
[/quote
U will jealous or not

[fri13th]

I try this technique,

I realised PIE and BKE or KJE, a lot of slope, whenever, there is a downward slope, I free my gear to N, gain 10 to 20km/hr, on downward driving. If you travel often from North to West often, you know what I meant. Then keep speed around 65 to 75km to achieve low rpm (1.2 to 1.5). Pick up slowly,especially 1st gear, at traffic junction. Shift to N at Stop position.

Results : 630KM cover with 35L or 410 with 22L of petrol.

Just ondering, this shifting gear from N to D, will it damage or wear out the gear faster ?

Travel at speeds of 65-75 in expressway? will road hog or not?

[detach8]

u shouldn't cruse in N. it damages your gearbox.

I try this technique,

I realised PIE and BKE or KJE, a lot of slope, whenever, there is a downward slope, I free my gear to N, gain 10 to 20km/hr, on downward driving. If you travel often from North to West often, you know what I meant. Then keep speed around 65 to 75km to achieve low rpm (1.2 to 1.5). Pick up slowly,especially 1st gear, at traffic junction. Shift to N at Stop position.

Results : 630KM cover with 35L or 410 with 22L of petrol.

Just ondering, this shifting gear from N to D, will it damage or wear out the gear faster ?

[limck007]

Yes, idling is discouraged because idling occurs when you stop, which means engine rpm is not enough to keep engine running without using fuel.

At high speeds like 45 and above(for me), when u lift your leg off accelerator, fuel injection stop, thus engine braking. If you don't believe, try this:
1.Get your speed up to 70-80km/h.
2.Release accelerator. Your car speed should slow down very fast. This is engine braking, and no fuel is being consumed at this point.
3.At around 45km/h, you should feel a jerk as fuel injection resumes and your car is free wheeling(less engine braking).
This is tried and tested on 4AT. For CVT, your mileage may vary.

i do get the engine braking feel when i life off the acceleratior after i hit 80 or 90km/h. when it fall till 60km/h, i step again to pick up to 80/90 loh.

but 2 questions here>>

1)when i approaching traffic light, is it better for me to swtich to N then slowly break  & rest at N
or
i brake slowly to a stop (in D mode) then switch to N to wait for traffic light to turn green?

which is better >??

2)Since idling is discouraged, if i am stopping at traffic light, do i switch to N or P or leave it at D??

[liewks]

The Versa Service manual states (CVT):

Lock-up clutch is engaged when vehicle speed is approximately 18 km/h (11 MPH) to 90 km/h (56 MPH).

It is likely that DFCO is maintained at least until lock-up is disengaged. Lifting the foot off the accelerator pedal quickly tends to nudge the ECU into DFCO. A quick gentle tap helps to cancel DFCO. Watch the tach + speedometer and you can guess what the ECU/TCM are up to.

For CVT's, the highest gear ratio gets you 10km/h for every 200rpm. So 80km/h happens at 1600rpm. Accelerating in an overly enthusiastic manner will guarantee that the TCM (transmission control module) never allows this gear ratio until you brake/shift into N/etc... and re-accelerate at a more moderate pace.

While the HR15DE generates maximum torque at ~4400rpm, it does not mean that the engine is actually generating peak torque at 4400rpm under all conditions. It really depends on the engine load. Idling the engine at 4400rpm is not going to give you 140Nm of torque. There is an interplay between throttle, RPM and transmission loading.

[SoL]

u shouldn't cruse in N. it damages your gearbox.

Is there any proof of this? Because some cars do, some cars don't.
Specifically, latio repair manual?

[fri13th]

The Versa Service manual states (CVT):

It is likely that DFCO is maintained at least until lock-up is disengaged. Lifting the foot off the accelerator pedal quickly tends to nudge the ECU into DFCO. A quick gentle tap helps to cancel DFCO. Watch the tach + speedometer and you can guess what the ECU/TCM are up to.

For CVT's, the highest gear ratio gets you 10km/h for every 200rpm. So 80km/h happens at 1600rpm. Accelerating in an overly enthusiastic manner will guarantee that the TCM (transmission control module) never allows this gear ratio until you brake/shift into N/etc... and re-accelerate at a more moderate pace.

While the HR15DE generates maximum torque at ~4400rpm, it does not mean that the engine is actually generating peak torque at 4400rpm under all conditions. It really depends on the engine load. Idling the engine at 4400rpm is not going to give you 140Nm of torque. There is an interplay between throttle, RPM and transmission loading.

Bro u sibei technical in ur post but hor too chim i see liao  just wondering are u a engineer?

[LatioR]

hi bro, u should minus 2~3 l to calculate the correct FC mah..rite?
[/quote
U will jealous or not

hi bro, not jealous lah, envy more likely ..my last FC only at 12.5km/l bcos of total jammed hr @90mins (both in and out from Sg)