100+ hypermiling / ecodriving tips & tactics

[jtgh]

keep in mind, that most obd2 tools do NOT know which mode the ECU is running in.
for any reporting of MPG or fuel used absolute.

Cold start.
warmup
hot run
accel. (fast gas foot) switches modes. !)
wot
unflood.
deceleration (in gear or out of gear)

it just dumbly assumes, stocheometric AFR. this is far from accurate.

IMHO

[McTimson]

The MPGuino is tapped right into the fuel injectors, and shows 0.00 gallons/hour of fuel being used under DFCO. OBD2 tools use sensors, but the MPGuino reports right from the source, and the source says no fuel is being used.

[jtgh]

have both , and DSO and 3 diff full logging, OBD2 Scan tools. ( 96 era to present)

the MPGuino, is the cheapest path to the answers.

the Sensor way , is not any good for the reasons stated.
it is a calculated value and not a sensed value.
A derived result that only comes close when cruising. (and then only after a careful calibration of the tool)

the MAF in no way senses gas flow.

[milesgallon.com]

Maybe I'm making a fool of myself for asking, but can you explain what an MPGuino is? I've never heard of it.

[Christ]

It's a simple little tool based that works like a ScanGauge for those among us who can't use a ScanGauge. It's also cheaper, in that it comes as a preassembly, or a DIY kit.

The only foolish question is the one that goes unasked. The only way you can truly be foolish is to think yourself a fool for the desire to learn.

[milesgallon.com]

Is there a place you can buy the MPGuino online? And of course I'm wondering, if it's a do it yourself kit... is it difficult to install? Anyone here that have done it?

[wkiernan]

I have a question regarding tip #44:

When you *have* to slow down, here's an approximate hierarchy of methods, from best to worst.

1) coasting in neutral, engine off (ie. roll to a stop);
2) coasting in neutral, engine idling;
3) regenerative coasting (hybrid vehicles)
4) regenerative braking (hybrid vehicles)
5) coasting in "deceleration fuel cut-off" mode (in gear, above a certain engine RPM)
6) conventional friction braking (non-hybrid or hybrid)

My car ('99 Miata) has a manual transmission. I have read that when it's coasting in gear the ECU cuts the fuel feed to zero. In contrast, when the engine is idling while coasting in neutral, the ECU not only feeds gas to the engine to keep it turning, but it feeds more gas than when it is idling in neutral at a standstill. You can see this by watching the tach; in neutral, it idles at 1100-1200 RPM as long as the car is moving at all, then the instant the car comes to a complete halt the idle speed drops to 800 RPM.

So if I engine-brake up to red lights or stop signs, momentum I'm trying to burn up anyway keeps the engine turning, which powers the alternator, power steering, oil and water pumps and even the a/c for free (that is, with zero gas consumption), whereas if I put it in neutral and use the brakes to slow down I have to burn gas to run all those appliances.

Am I missing something here? When I finally break down and get a Scan Gauge I'll be able to tell what's going on better.

[MetroMPG]

Hi, wkiernan -

To be clear, #2 should say "rolling to a stop" as well. The distinction being that rolling takes you significantly further than engine braking in fuel-cut mode. Which necessarily means you used less fuel up to the point of beginning the coast (assuming you're able to roll right up to the stop).

You're right that if you need to bleed speed faster than a pure neutral coast, decel fuel cut off mode (DFCO) is a good tactic in a non-hybrid.

[hackish]

wkiernan, I read the list and was going to post the exact point you just made and Metro answered. Although some of the ideas in the list are good, most of the techniques listed are actually just good ways to trick OBD2 scan gauges into showing you a better MPG than you're actually getting.

The other point of the list is that while it may it may give you better fuel economy it is more likely to encourage other roadusers to expend more fuel. If faking a turn for example might get others to pass you or it might just get them to brake anticipating your slowing down. It might also piss them off, getting them to accelerate to get around you. So you saved 0.1l of fuel hypermiling home but caused other roadusers to expend 2l of fuel avoiding you.

The whole pulse and coast thing is also very specific and if you shut your engine off for the coast will make your general mechanic very happy. Starter motors are engineered to last for X number of starts. It also puts a significant drain on your battery and you then have to expend extra fuel charging it up again. You can bump start the car too but that puts significant wear on your clutch as they are not designed to be shocked in the opposite direction (breaks the steel straps in the pressure plate). So you might save $100 in fuel but spend $1500 on a new clutch.

Also, an accelerating engine produces more emissions and burns a lot more fuel. During cruise many vehicles use EGR and lean running modes to improve efficiency. They don't operate immediately after a start.

Finally, I have one last thing that can be added to the list.

Use the lowest octane fuel approved for your vehicle. Not only is lower octane fuel cheaper but it has more BTU's of energy per litre. Some vehicles do get better economy on the higher octane fuel but most do not. Depends on the tuning of the vehicle from the factory.

-Michael

[MetroMPG]

Michael, you raise some valid points.

As for the ecodriver/hypermiler's impact on other road users, please note the introductory text on the tips page encourages people to take other traffic users into consideration.

Originally Posted by hackish

most of the techniques listed are actually just good ways to trick OBD2 scan gauges into showing you a better MPG than you're actually getting.

Could you give examples?

Regarding pulse & glide:

Starter motors are engineered to last for X number of starts.

Agreed, and we know of at least one heavy pulse & glide user (with automatic transmission) who has had to replace a starter, presumably for this reason.

It also puts a significant drain on your battery and you then have to expend extra fuel charging it up again.

The depth of discharge of course depends on electrical load and time.

You can bump start the car too but that puts significant wear on your clutch

I suggest clutch wear is more a function of the driver than the technique itself. (In other words, it can be accomplished with varying degrees of harshness to the components.) We have anecdotal evidence of this technique being used for hundreds of thousands of miles with no clutch issues.

Use the lowest octane fuel approved for your vehicle. Not only is lower octane fuel cheaper but it has more BTU's of energy per litre. Some vehicles do get better economy on the higher octane fuel but most do not. Depends on the tuning of the vehicle from the factory.

Interesting - didn't know the energy content was different by fuel grade.