Questions tagged [fuel-consumption]

Use for questions related to fuel economy.

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22
votes
7answers
313k views

Is idling bad for your engine?

If I sit in my car for 30-40 minutes with the AC and the car idling, does that "hurt" the engine, or does it simply waste gas and pollute the air? Would it be better if I turned off the car? A ...
16
votes
8answers
6k views

Is shifting to neutral on a decline more fuel efficient than keeping the gear engaged?

I always had the habit of shifting to neutral on long declines and using the brakes to slow down as needed. Intuition made me believe I'd be saving fuel as opposed to keeping a gear engaged. However, ...
7
votes
1answer
44k views

What does a healthy spark plug look like?

The spark plug pictured here: Has some black carbon on the underside of the ground electrode and has black carbon on the "base" area below the centre electrode (not pictured). Is this normal and ...
9
votes
3answers
60k views

Engine Size and Fuel Consumption

I have this weird misconception that the engine size is related to the amount of fuel being burned in one cycle(4-stroke engine). I know this is stupid but how does engine size relate to the amount of ...
17
votes
2answers
6k views

how to optimize fuel consumption by changing the rear differential ratio?

Is it possible to improve the fuel consumption (decrease it) in my van by changing the rear differential ratio? I would like to optimize it for low-speed driving about 40 km/h (25 mph). Is it true ...
9
votes
6answers
5k views

Fuel consumption at same speed of different engine

I am wondering why two car running at 100 km/h for example with a 100 hp consume less fuel that an engine of 300hp. Even if I take a supercar lighter and more aerodynamics it will consume more. But ...
14
votes
6answers
27k views

How to improve fuel economy in high-mileage car?

I'm driving an 2003 Acura TL 3.2 with 177K miles on it. I bought the car with 110K miles on it. It seems to me that the car is not getting the same fuel economy that it did when I acquired it. I ...
7
votes
2answers
335 views

How much can sub-optimal octane affect efficiency or power?

Suppose a production fuel-injected engine is tuned for 93 octane fuel. As I understand it, the engine can still run on lower-octane (i.e., less knock-resistant) fuel, but it will pull timing to avoid ...
1
vote
3answers
8k views

Fast Idle and High Fuel Consumption

I just bought a Manual 97 Mazda Lantis 323 1.8L DOHC 16 Valve BP and I was amazed that it went through 1/4 tank gas ( about 12.5 liters or 3.3 gallons ) in one day after about 60 kilometers / 37 miles ...
21
votes
4answers
5k views

Does flooring the throttle while traveling at lower speeds increase fuel consumption?

I've noticed that in a manual transmission vehicle when going uphill I have two options: Downshift and press the gas more Stay in the same gear and press the gas more I haven't measured it but ...
16
votes
13answers
254k views

Is the ECON button just a placebo?

I recently bought a Honda Civic that had this in the car: I have no idea what it does, and how it's supposed to help. Even Honda's website is ambiguous, just using a lot of fuzzy words to describe ...
8
votes
3answers
4k views

Calculating MPG from MAP sensor (or converting MAP data to MAF data)

My 2002 Honda Accord V6 has a Manifold Absolute Pressure sensor (MAP). I understand that this sensor gives out information in pressure units (psi or equivalent). After doing a bit of research, I ...
6
votes
1answer
5k views

Oily Sludge in the Intake Manifold

When taking off the throttle body to clean my IAC, I noticed that there was a thick layer of oily sludge coating pretty much everything inside the intake manifold: I have two queastions: How did ...
3
votes
3answers
6k views

Need to know about spark plug

What is the most suitable spark plug for Toyota 3A engine in Asia? (NGK/Champion/denso/BOSCH and also copper/platinum or iridium) Please explain the differences/advantages between them and how it ...
2
votes
0answers
2k views

Fuel Consumption and other Fuel related data from basic OBD-II parameters [duplicate]

I want to know how can i obtain the values of Fuel Consumption, Fuel Economy and other fuel related information from basic OBD-II parameters like Vehicle Speed, RPM, TPS etc. I have noticed that not ...
17
votes
4answers
3k views

Are there any advantages of idling a vehicle vs. turning it off and back on again?

I was sitting outside, eating my lunch the other day, and a small bus (you know, one of the short ones) pulled up to the sandwich shop I was eating at. I noticed that the driver got out of the bus, ...
9
votes
3answers
47k views

Is topping up the oil enough of an oil change?

If you use synthetic ester-based oil in a relatively new petrol engine, top it up regularly, and the engine runs very quietly and basically without any noise whatsoever (especially after another top ...
5
votes
5answers
1k views

Can I save money using E85 in my flexible fuel vehicle?

Where E85 Ethanol is available (not very common), the price per gallon is often lower than regular unleaded gasoline. Though I've read that fuel economy is commonly reduced by 20% or more, when using ...
0
votes
1answer
5k views

How can I calculate MPG using an OBD-II Device

OBD-II provide following readings Mass Air Flow (PID 0166) Fuel–Air commanded equivalence ratio (0144) Can these be used to calculate the actual fuel consumed? Is the output correct?
9
votes
8answers
17k views

Fuel efficiency and Shifting/RPM

I was reading a thread in a car forum where someone wrote: The lower the RPM, the less fuel you use, the less strain you put on everything.. Another person then replied, stating: Not true. If ...
6
votes
4answers
3k views

Does the tachometer provide any indication of fuel usage?

So, I'm driving along on the highway with the A/C blasting when I notice the price of gas. It makes me think, "what can I do to increase my fuel efficiency?" Some of the tips I've heard have included ...
15
votes
2answers
101k views

How much does spark plug gap affect fuel efficiency?

I've read conflicting reports regarding how plug gap can affect fuel efficiency. For example, I've read that too small a gap won't cause a clean burn, or that too large a gap can cause misfires due ...
15
votes
6answers
14k views

What makes two-stroke engines less fuel-efficient than four-strokes?

It is a commonly-held belief that two-stroke engines are less fuel-efficient than four-stroke engines, and some example BSFC figures appear to confirm this as well. But what is it that causes two-...
6
votes
1answer
1k views

Can the viscosity of the oil affect gas mileage?

If a manufacture recommends a certain weight of the oil for the engine, lets say 5W-40 and instead 5W-30 was used, would the gas mileage of the engine increase as the piston does not have to do as ...
6
votes
3answers
1k views

Tapping into the on-board computer

I'm thinking of replacing my car's radio panel with a custom built Raspberry Pi device, something like this device. However, it's usefulness would be much larger, if I could get information from the ...
5
votes
1answer
641 views

How to calculate fuel consumption and CO2 emission on flex fuel cars using OBDII data?

Here is the thing: I'm trying to estimate the fuel consumption of cars using OBDII data. It's quite simple if we can treat each fuel and its stoichiometric air fuel ratio separately, but when it turns ...
2
votes
3answers
710 views

Mileage varies by driving at different speeds

I drive my car a lot. I do lot of experiments with speeds while driving. Following are my observations: Driving at 60 - 70 km/h gives maximum mileage Driving at 70 - 90 km/h gives good mileage ...
1
vote
2answers
844 views

Calculating fuel flow rate through obd || sensor not supporting 015E and 0110 commands

I have been working on a project where i want to calulate fuel flow rate using data from the obd2 sensor. The car on which i was testing didn't support the pid 015E which is for fuel flow rate. Then i ...
0
votes
2answers
2k views

Royal Enfield classic 350 engine off while running

I bought a brand new Royal Enfield Classic 350 and I rode around 1200 km. Since the delivery of bike, I have faced a recurring problem with the engine shutting down while the bike is running. When I ...
14
votes
4answers
15k views

Does accelerating faster worsen fuel efficiency?

I've often heard that accelerating harder makes for bad fuel efficiency, but have yet to be given a sound explanation of why. Naturally this makes me question this advice. Now obviously when you ...
11
votes
1answer
2k views

Brake Specific Fuel Consumption of 2-stroke vs 4-stroke

How much fuel do various types of engines burn per power output? I'm especially interested in naturally aspirated piston engines, and comparing two-stroke to four-stroke. The wikipedia article gives ...
9
votes
1answer
5k views

Does leaving the choke closed increase fuel consumption

I ran out of fuel using my outboard engine the other day, when I had checked the tank beforehand and thought I saw plenty of fuel. I had forgotten to open the choke for twenty minutes or so. My ...
8
votes
2answers
649 views

Driving slower at low constant rpms or driving fast to get to destination faster, which saves more gas?

As the question title says. I am a new driver and I understand that driving at higher RPMs can burn more gas faster. However getting to a destination longer would mean you were spending gas at a ...
8
votes
2answers
4k views

Low power, bad gas mileage, smelly exhaust after engine work

My 92 Civic has had low power (need to use at least one gear lower than usual to get the same power) and has been getting bad gas mileage (15-25mpg vs 32-42 mpg usual) since I replaced the head gasket....
5
votes
3answers
1k views

Is manual start/stop good on older cars?

I have an old car (but with electronic injection) that predates by far start/stop systems which are used nowadays to save fuel (turning off the engine brings savings after 3-5 seconds, see Calculating ...
4
votes
2answers
4k views

Car average mpg display correctness

I have been wondering about the correctness of the average MPG displays on modern cars. Mine in particular is a Renault Modus. What I did is fill the tank, drive around and then refill the tank to see ...
4
votes
2answers
219 views

Fuel Economy Gauge Modification

I have a little digital screen in my dash that re-evaluates my average fuel consumption (L/100km) every thirty seconds. How can I modify this to increase the reporting frequency? Preferably, at least ...
3
votes
3answers
2k views

How to calculate fuel consumption?

If i know the rpm at which the (tachometer indicated) engine is running and the current speed and the engine capacity is there a where to calculate the fuel consumption of the engine? Need not be a ...
2
votes
3answers
2k views

Is Petrol usage Proportional to Gas Pedal position

I was wondering about this the other day. Is the petrol usage in the car only influenced by the position of the gas pedal? So for example if I take my foot of the gas and coast for 30 seconds, would ...
1
vote
0answers
374 views

Cars with single fuel type how retrieve tank level to dashboard?

I see that BiFuel cars had fuel level and type readable from ECU by using pid 0151 and 012F. Cars with monofuel don't have this pids sensors, so how the dashboard retrive the fuel level? Maybe the ...
0
votes
2answers
2k views

High fuel consumption/1997 Toyota corolla

The wire to fuel pump is not having current I therefore bypass it. Can a car consumption increase if ecu is bypass?