Downhill : neutral or coast in gear

[bennjamin]

technically when u step on ur accelerator it pumps fuel from ur tank.. if ur coasting and ur not steeping on ur accelerator ur not wasting fuel right?

yes - "at speed" if u coast in gear , the injectors are off and the engine is run by momentum. I cannot say exactly at what load they go on and off - but the reason why you get more k's per tank on highway driving is that there is longer instances of "coasting" etc.

[CRXer]

Ok..let me have another go at this......

i was told a while ago,by string i think,to open up a .bin editor & see that the fuel values for coasting are not zero.....

well,i went one step further & datalogged a coasting event & what do i find...........

coasting= injector opening of 0ms,duty of 0%

this is in keepin with what honda says that they shut off the injectors when rpm over about 1000rpm & closed throttle.

I was told by a few of strings lap dogs (i apologise if it wasnt u,& whoever it was was still tryin to be civil except for his parasites)that i didnt know wtf i was talking about.

Anyway heres a shot of the log showin at the cursor(black dotted line) duty =0,inj = 0

Anyone want to comment?

[JasonGilholme]

ya hit the nail on da head man.

[SINISTR]

an Idling engine is always said to use more fuel than an engine which is at cruising speed as due to the cars moving inertia its easing load on the engine and allows for less fuel consumption.

Your engine is a power generator, when its idling it needs a certain amount of fuel to basically RUN and turn it over. Same when you're accelerating off the lights or going up a hill, it needs higher revs to make more power and in return it uses more fuel. When cruising at 100km/h in 5th gear for 30 mins its using less fuel than if you idled your car for 15 mins in the garage because the gear ratios actually let the engine do less work, less than idling anyway - so definatelly cruise in 4th/5th down a hill.

[TRU32U]

soooooooooooo is everyone saying if im in 5th and sitting 140kms hr on m4 for example its better to cruise and hold revs at say 4500rpm for 15 mins or so then letting it roll in N??

[e240]

I say if you need to come down this route just to save fuel, take a bus.

[quangsta]

^^^^ lol

interesting.....topic though..

i think coasting in gear maybe more efficient...but more so the fact that its safer being in some sort of control of ur speeds and it will save you money on ur brakes anyway...

[Q_ball]

I say coasting in gear > neutral anytime, not for tite ass purposes, but for safety!!

And yeh, as above, if you really had to decide whether to coast in neutral or gear, for FUEL saving purposes, lol, dont drive!

[Vinnie]

i also think its just hilarious that sum1 who has forked out to get a nice car like an ITS is so paranoid about the extremely small amount of difference coasting in/out if gear makes on fuel consumption. If its such a prob u shooda bought urself a 1.3 litre shitebox... i mean ffs jus leave the thing in gear!

[TypeRice]

only roll downhill in neutral if you r in heavy traffic.

[CRXer]

the man asked a simple tech question & wanted to know an answer & he gets the "but what about the children" brigade tellin him the finer aspects of wrappin yourself in cotton wool by always being in gear & the full fuel savings report...........

seriously..if u got nothing to contribute........dont make it obvious u got nothing

[[HIREVZ]]

soooooooooooo is everyone saying if im in 5th and sitting 140kms hr on m4 for example its better to cruise and hold revs at say 4500rpm for 15 mins or so then letting it roll in N??

going 140 on the m4 ur going to have to hold speed at 140 so u would have to press the trottle n keep throttle body open, downhill u dont use throttle therefore throttlebody closed using less fuel