Friday, 1 May 2015

Gaining Fuel Economy on a Honda

Updated May 10, 2015

My personal challenge to gain more from distance from the fuel.


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Today i gain the best fuel economy of 13.8 km/l or 32.47 mpg, effectively broke into the 700km range for a tank of fuel, 51 litres. Yay!

Much of european makes yield great fuel economy. What about Japan made vehicles?


This will be a little sharing of what I did and putting to rest some myths that we read online.

A little history and background on how I arrived here.

Over the past one year since I took ownership of a 5 year Honda Stream then (see below), I replaced components and studied it trying to figure out how the car works.

Anyways, The Honda Stream is a variant of the Honda Civic, powered by a R18A motor.



A little history

The motor saw a head gasket burn which saw the car doing 300 km on a 50 ltr fuel. (6kpl or 14 mpg) There is also an oil sludge situation which I cleaned up with manually removing the carbon bits and frequent oil change. No engine flush for me!




Today, the motor is doing well above and exceeding that.

You can follow me on fuelly.com for the ride.


There are two areas of improving the fuel economy of the vehicle.
Part 1. Vehicle
Part 2. Driving Style.


Part 1: Vehicle


I am targeting sensors that have an effect on fuel delivery since it is totally controlled by the ECU (Engine Control Unit). The accelerator pedal is control for the throttle plate (Air).

1. Mass Air Flow Sensor Cleaning


Item 21: 37980-RNA-A01

The single most effective gain on fuel economy happened after the MAF Sensor (Mass Air Flow) was sprayed clean with electric cleaner which can be used on plastic.


An improvement of the procedure in the link above: There is no need to disconnect the battery terminals. Unplugging the wire harness to the MAF sensor will achieve the same effect.

Air dry the MAF sensor.


2. The Upstream and Downstream Sensors

The theoretical lifespan of these sensors is rated around 100,000 km. 
The Oxygen and Air-Fuel sensors control the stoichiometric air-fuel ratio that results in Rich burning or Lean burning. This affects the fuel delivery by the computer system.

I have found both sensors sold online that are legit parts at a fraction of the price compared to agent prices.


Oxygen sensor (Item 13)
36532-RNA-A01  USD $62.11

A/F Sensor (Item 12)
36531-RNA-003  RMB $400


Both works from my usage for the last 9 months.

Here are the specifications of my ride:
1. 35 psi Tire
2. Shell 5w-40 synthetic oil
3. Caltex 92 fuel
4. No spare tire - Actually the additional weight of the spare tire made no difference.
5. Minimal Air conditioning use.
6. Techron Concentrate Plus before oil change.


Addressing myths:
Fuel grade: The Honda R18A can run safely on regular octane 92. 
There is no pinging or loss of power at start. Why? The engine ECU learns and adapts itself and our drive habits. 

Part 2: Driving Style

The dashboard has the green ECO light and we are encouraged to see it lilted up as much as possible.

This list can be commonly found on most economical drive websites

Ultimately, the driver's foot determines how the motor will run.

Here's an extract from the web link with some of my feedbacks.
• Use high gears - Use the highest gear you can without the car ‘labouring' or struggling to keep going. Try to change gear as early as possible, and try not to exceed 3000rpm under normal driving conditions. 
Much of my speed at 60kph runs only at 1400 ~ 1500 rpm. I rarely rev above 2000 rpm for all gears.
• Control your right foot - When using the accelerator make very small adjustments to regulate your speed. The more you push the pedal, the more fuel you'll use. Bear in mind that full throttle should never be used when you're trying to save fuel. 
• Plan ahead - Try to anticipate the road ahead, and use both gravity and traffic to your advantage. If you're about to go over the crest of a hill, back off the throttle until you're going downhill again. With gravity helping you, less use of the accelerator will be necessary to keep your speed up. Try to leave big gaps between you and the car in front in order to keep rolling. Stopping and starting constantly will use more fuel than keeping the car moving. 
I choose the highway over routes with more junction lights even when it is a bit farther to travel.
• Reduce braking - Avoid using your brakes as much as you can. Cruising on the lead-up to a junction will be much more fuel-efficient than driving normally and then slamming on the brakes. 
Looking beyond the car in front helps in throttling. It helps us keep a safe distance in accident prevention too.
• Slow down - When on motorways, less speed is better. Although the national speed limit is 70mph, cruising at 60mph or even 50mph will save a lot more fuel. 
Agree. The wind drag always upsets fuel investment above 80 kph. Where possible 70 kph is the ideal fuel return on speed.
• Don't idle - Always set off as promptly as possible, avoiding leaving the engine idling. When in traffic for extended periods it's a good idea to switch the engine off to avoid using fuel unnecessarily. Many new cars are coming onto the market with systems that do this for you, often known as stop/start. 
• Open windows - In hot weather try opening windows instead of using air conditioning. Both methods of keeping cool use more fuel, but having windows open is much more efficient than using power-sapping air conditioning. 
• Coasting is wrong - Coasting (letting the car roll in neutral rather than being in gear) means you're not totally in control of your vehicle. If you leave the car in gear when decelerating then you're still using no fuel, but can make use of ‘engine braking' which also takes some of the load off the brakes. 
Leave it on 'D' in auto transmissions. The engine will not use more fuel. It's safer too when you demand power to avoid accidents.
• Turn off electronics - Many electronic features on your car uses engine power and increases fuel costs. Turn off items like heated windscreens, de-misters and headlights when you don't need them.