My Car Consumes Fuel. I’ve Tried EVERYTHING. What Do I Do?

Naturally, I was concerned, and I asked a few questions to help me get a feel of the consumption he was complaining about and importantly, the things he had done to sort the situation and why he believed the issue still persisted.

According to him, the injector nozzles had been taken apart and ‘serviced’; the spark plugs had been changed, and one other thing, which I don’t exactly remember now.

I probed further – asking what engine oil type he used in the 2007 1ZZ-FE engine. He replied that it was a 20W50 variant. I was curious if he still had a thermostat in the engine.

The reply was negative.

I asked him to simply revert the vehicle to run the way it was intended, and he would be fine. However, that was a challenge, and I had to break things down into bits about what I meant.

This entry is meant to serve as an ultimate checklist (resource, if you will) for helping when your vehicle consumes more fuel than it’s reasonable.

Here, I’ll share what you need to do and importantly, how that action negatively impacts fuel efficiency.

In these days of soaring gas prices, this entry will help ensure that the money spent at the pumps is well spent and serves its intended purpose.

So, what should you be checking on your vehicle when it decides to consume more gasoline than is reasonable?

Here:

1. The Right Weight Engine Oil

Engine oil plays a very important role in lubricating an engine, stopping metal-on-metal contact in the process.

To make this happen effectively, engines are designed with a particular engine oil weight in mind.

For the Toyota 1ZZ-FE engine, the right weight is 5W30. Unfortunately, the fellow who had a challenge with poor fuel economy admitted that he was using 20W50 engine oil weight for his vehicle.

Recently, some hybrids now require and take 0W8, an oil weight so thin that it could easily be mistaken for water!

If you’re using an engine oil weight that is considerably thicker than what your vehicle manufacturer recommends for your engine, your MPGs will go down – and the thicker you go, the worse your MPG is going to be.

But, why is this so?

Why the Right Weight Engine Oil Is Important

Engine oil follows narrow (usually compact) routes to lubricate an engine. For most modern engines designed to work with thin-weight engine oil, these oil pathways are equally small – just enough to accommodate that weight.

In mechanicspeak, it’s called ‘tighter clearances’.

When an engine, designed to work with 5w30 (like the Toyota IZZ-FE mentioned above), is ‘fed’ the 20W50 weight oil, the oil struggles to flow in a manner that will make it serve the engine efficiently.

This challenge results in less than ideal engine protection and conversely, friction isn’t taken out, as it should.

With friction present, higher RPMs are needed to pull the motor, and naturally, more fuel is burned in the process.

However, these aren’t all the challenges that there are when the wrong engine oil weight is used. Thicker-weight engine oil struggles to flow when cold and for the first few seconds, leaves the top of the engine starved of oil, facilitating the quick wear of the top components of an engine.

Looked at from whatever angle, it’s difficult to justify the use of thicker engine oil than recommended, unless in some special cases.

Finally, putting thicker oil than recommended into a vehicle’s crankcase will result in the premature wear of the oil pump – which is forced to pump engine oil thicker than what it has been designed and rated for.

2. Presence of an Engine Thermostat

An engine thermostat, usually inserted into the thermostat housing and leading directly to the engine block has just one function: it controls coolant flow; stopping it and allowing it as needed.

In the morning (or during a cold start), the thermostat closes up, depriving the engine core of cooling fluid and forcing it to heat up quickly.

Without any sort of cooling, the engine has no other option but to quickly heat up to operating temperature, getting the associated O2 sensors and catalytic converters to fully ‘warm up’ and begin operations.

The open loop the vehicle was in when it was cold changes to a ‘closed’ loop – meaning the running of the vehicle is taken over by the ECU, getting inputs from the vehicle’s sensors, majorly the O2 sensors.

Most thermostats fully open between 180 and 195 degrees F (vehicle and thermostat dependent) at which point, the fans kick in to keep the temperature.

So, what happens when an engine thermostat is yanked away for whatever reason and a vehicle is forced to run without one?

Why an Engine Thermostat Is Important

Unfortunately, in most of the developing world, the first thing ‘mechanics’ do is remove a vehicle’s thermostat, claiming that a vehicle being driven in the tropics has no use for it.

Sometimes, the thermostat manages to reach a year (or more), and then, for some reason, the vehicle overheats. Once this happens, the first thing the ‘mechanic’ does is to yank off the thermostat and in most cases, this solves the issue…

…only that, it causes another more serious one.

As indicated earlier, the opening and closing of the thermostat is strictly to help the engine get to operating temperature faster, so that the ECU will take over fuel management. The ECU, remember, gets inputs from such sensors as the O2 sensors which only work when they are heated by an engine that has reached operating temperature.

Now, whether the excuse for removing a thermostat is overheating or that the vehicle isn’t running in a temperate region again (these are dumb reasons, BTW), the net result is the same: the engine doesn’t get to operating temperature, and as a result, the O2 sensors never heat up.

The ECU still thinks the engine is cold and dumps fuel in it to keep it from stalling, as per its open loop instruction.

Only one result flows from here: poor MPGs.

3. ‘Relayed’ Fan

The cooling fans on an internal combustion engine come on after the thermostat opens and yet, somehow, the generated heat from the engine starts to rise beyond safe limits.

This happens when the ECU gives the command; with the ECU itself getting its clues from the Coolant Temperature Sensor.

Before this event, the electric cooling fans don’t turn: they remain quiet and even when called upon by the ECU, they cycle on for about thirty (30) seconds, then, switch off again.

Unfortunately, for crazy reasons (usually overheating), the cooling fans are routed directly to the starter battery, making them start turning, immediately the ignition is inserted and the key, turned. Essentially thus, the cooling fans turn before an engine gets the chance to roar to life.

If the settings of your cooling fans are like this, fuel economy will certainly be far from that engine.

But, why is that so?

Why the Cooling Fan(s) Must Always Run On Relay

Contrary to what many car owners and some half-baked mechanics believe, an engine needs to always run ‘hot’.

This is what is called ‘operating temperature’ and the engine runs best in that state.

The cooling fans, working continuously, negate this, blowing down air continuously to cool down an engine that doesn’t need cooling!

With an engine running cold as a result of this, the ECU is tricked into believing that the vehicle is going through a cold start and instead, dumps fuel to compensate and avoid stalling…

…and you all know how that winds up!

Besides fuel consumption, fans running continuously will wear out quicker than the units that work just a 3rd of that time (or less) – as originally intended.

Why expose your pocket to extra expenditure at the pump and in replacing your cooling fans if it can be avoided?

4. The Engine Air Filter…

I once popped open an engine hood and decided to check on the air filter assembly. I could swear, with confidence, that the engine was driven through severe dust and mud, almost daily and the engine air filter was thoroughly neglected for at least five (5) good years!

The unit was as if it had been through hell and back and I silently wondered how any air got through, in the first place.

Needless to say, the owner of the vehicle complained, severely of poor MPGs – but curiously, also refused to apply my honest recommendation of changing the air filter for better results…

…I simply shook my head and walked away.

Why Keeping the Engine Air Filter Clean Is Important

For an internal combustion engine to keep moving, it must burn fuel. For this to happen rightly, air and fuel must be present in the combustion chambers so that combustion takes place and power is produced.

An abundance of air and fuel will produce the most power and a dire shortage will produce just the minimum.

When there’s too little air, the injectors, working on the orders of the ECU also offer a corresponding amount of fuel. This works in theory but the power produced is abysmal, at best.

To compensate, the throttle needs to be open and this is when poor MPGs enter. The throttle, depressed at say 25% (for want of a better explanation), will need to be depressed up to 60% to get the usual power; power that would have been gotten at 25% ‘depression’.

This difference is where the poor MPGs enter and make home.

5. Driving Style

Driving is fun – especially in a RWD sports-biased sedan. With a V6, V8, or even a charged 4, the desire to go hard on the accelerator is real. The fun is also second to nothing else a true petrolhead will ever experience.

But, power and fun come at a cost: with an open throttle, gas literally ‘evaporates’ and in a few days, you’re back at the gas station again…it’s a never-ending cycle.

You see, there’s nothing in life that comes without a consequence: for every action, there’s a consequence…there are no two ways around it. It’s as simple as that.

If you drive a Mercedes, BMW, or a Lexus GS – and drive them like they were originally designed, you’ll have to make friends at the gas stations fast – or, alternatively, consider a Prius.

There’s a reason why the 26.4-gallon fuel tank capacity of the Veyron empties in 12 minutes if you open it at its 250-mph full throttle capacity!

Why a Light Foot Is Important

Most engines are designed this way: at a lower RPM, they waste fuel; at a higher-than-average RPM, they burn fuel, unnecessarily. The key? Remaining within the thresholds – which for most vehicles is around the 1500 – 2500 RPM mark.

Granted, this is Granny’s style – but if you want to visit the gas station as sparsely as Grandma does, it’s her style or no one else’s.

It’s as simple as that.

Other (Very) Important Things To Check

The above are the most important when it comes to the business of getting the best gas mileage in your vehicle, irrespective of what you drive.

However, the list isn’t exhaustive. In addition to the above:

• Check O2 sensors and make sure they’re all working.
• Check spark plugs and ensure that besides using the recommended ones for your engine, you also use options that are still very good, not used, sad, pieces.
• Confirm that your brakes aren’t binding.
• Tackle any vacuum leaks you may have.
• Clean your MAF.
• Use the right tranny fluid and
• Keep your tires properly inflated.

Don’t forget to keep your car properly tuned up, while at it. Good gas mileage isn’t Nuclear Physics – and it doesn’t get more complex than this.

My Car Consumes Fuel. I’ve Tried Everything. What Do I Do?

Fuel consumption isn’t something complex and with the tips shared above, just about every vehicle will surely experience better gas economy and will be better for it, overall.

That said, there’s something that many miss in the quest for better MPGs…a Corrolla, all other things being equal, CANNOT offer the same (or better) fuel efficiency than a Yaris. MPG, remember, is largely a product of engine size and state of tune. You can’t give a vehicle what it doesn’t have.

Talking about engine sizes and state of tune, it’s important to first of all, see what your vehicle is rated for (and possibly, compare with another) before becoming upset…don’t go being bothered that your Hummer H2 isn’t as fuel efficient as a Yaris Plugin Hybrid.

Good luck!