If you can call 26.5mpg in a 4 cyl success...

[pumafeet10]

most of the time the on board mpg display is off and the thing you want to use the scangauge for would be to watch Load on your engine which is one of the most important aspects.

Also slowing down will help incredible, while you accelerate you want to do so briskly and no to let the engine bog or anything like that.

That is why the scangauge is great it is more accurate and shows certain things that are happening with the engine that the factory gauges do not.

For good gas mileage you want less power, b/c less power= better mpg the more power you have the more fuel you will use

[RobertSmalls]

Originally Posted by Mifunego

Unless your electronics tell you otherwise, I assume that you mean the pedal is 3/4 of the way to the floor? I'm not sure, however, how you accelerate slowly with a 75% throttle opening. I've been driving lately barely touching the gas. But there's no doubt, that would require some skilled feet!

The engine by itself would be most efficient at full throttle, but most ECU's will enrich the mixture once you pass, oh, 3/4 throttle. As to how I accelerate slowly, well, even the 2.2L Subaru with its nice flat torque curve doesn't make much power at 1500-2200RPM. And my 1.0L Honda engine is even better.

How low can you go without lugging the engine? Do that, at full throttle.

[puddleglum]

[QUOTE=Mifunego;156414]Robert /Puddleglum / luvit / the scangauge looks neat, but I already have the instant and average mpg display on the stock in-dash info display. I do enjoy watching the instant mileage number increase as I drive, especially coasting and watching it read up to 99.9 mpg What do you use your scangauge for? You're right in suggesting that the other realtime info could be amusing though. =QUOTE]

Having a stock mileage readout may make the SG a little redundant, but it will do more than read instant mileage. I use mine to monitor engine temp. since I run a grill block to help warm up and the factory guage isn't acurate enough. A cold engine is wasting fuel. Watching engine load is important and can be done through several different guages. Also, something Iv'e been thinking of doing, but haven't done yet is setting up a guage to watch fuel consumed. then I could accurately compare the fuel used to a given throttle position among other things. That might be helpful to you.

[nj1266]

Originally Posted by RobertSmalls

Driving without brakes, plus an engine kill switch, will help a lot if you're not doing so already. The Scangauge reports my Subaru idles at 0.25 gal/hr when warmed up, so you can do the math on how much fuel you might save by shutting down the engine during prolonged coasts in neutral, and at red lights.

You do not have to turn the engine off during the glide period after the pulse. All you have to do is keep the car in gear and lift off the gas. The injectors will shut off and engine will become an air pump. I have a wideband installed on my car and when I glide in gear with my foot off the gas and the engine on, the wideband reads 20.xx AFR. That means you are getting 20.xx parts of air to one part of fuel. That is way better than gliding when the car is out of gear and the engine is on becuase the AFR is 14.7:1 under these conditions. 20.xx:1 is far far better than 14.7:1 and that saves you more fuel. Ofcourse, shutting the engine off is best of all, but it is also dangerous as hell.

[alohaspirit]

If you can call 26.5mpg in a 4 cyl success...



I do, when I drive my Geo Tracker (almost got 29mpg once)

but yeah, scanguage helps a lot

[ATaylorRacing]

When you start gettting non-winter gas, non-winter tires, air them up to the max you'll get better. My 12 second SRT4 Neon got 26 mpg when I first got it since I knew that if I drove it like a normal person 87 oct could be used. When racing season started up the FE jumped to the EPA rating of 30 by only using 92-93 oct fuel. Good old hot rodding and tire pressure adjustments garnered me a bit over 40!

[RobertSmalls]

Originally Posted by nj1266

You do not have to turn the engine off during the glide period after the pulse. All you have to do is keep the car in gear and lift off the gas. The injectors will shut off and engine will become an air pump. I have a wideband installed on my car and when I glide in gear with my foot off the gas and the engine on, the wideband reads 20.xx AFR. That means you are getting 20.xx parts of air to one part of fuel. That is way better than gliding when the car is out of gear and the engine is on becuase the AFR is 14.7:1 under these conditions. 20.xx:1 is far far better than 14.7:1 and that saves you more fuel. Ofcourse, shutting the engine off is best of all, but it is also dangerous as hell.

I disagree.

Shutting off the engine isn't dangerous if done correctly. If you wait until the engine is hot, and use a fuel cut switch, there's very little risk of damage to the engine or other components. The loss of power brakes is very predictable, and if you don't press and release the brakes much, you retain assist. As for power steering, well, you don't need that anyway, but some cars have electric power steering or even manual steering.

The technique you describe is "pulse-and-DFCO", which underperforms pulse-and-glide. Spinning the engine during DFCO takes energy, and you slow down much faster than you would in neutral. Because P&G allows much longer glides, it's more practical so you can use it more often, and your car uses less energy per mile for more mpg.

BTW, your AFR should approach infinity, as you've got clean atmospheric air being pumped through the engine, and almost no combustion products mixed with it.

[nj1266]

Originally Posted by RobertSmalls

I disagree.

Shutting off the engine isn't dangerous if done correctly. If you wait until the engine is hot, and use a fuel cut switch, there's very little risk of damage to the engine or other components. The loss of power brakes is very predictable, and if you don't press and release the brakes much, you retain assist. As for power steering, well, you don't need that anyway, but some cars have electric power steering or even manual steering.

There are so many things that can go wrong when you shut off the engine. Among them:

1. Your steering can lock if you inadvertantely turn the key all the way back to the complete off position. That is damned danegerous if you ask me. The last thing that I want is for my steering wheel to go into the lock position while gliding down from 65-70 mph. It just scares the hell out of me. Sorry, I will take the trade-off of less fuel economy for safety.

2. The brakes lose assist and ABS. You might get away with it while gliding, but what if you need to stop in an emergency while gliding. It can happen if you are a dedicted hypermiler. You have no idea what circumstances can come up when driving. Pretty dammned dangerous if you ask me.

3. There is a lot of wear and tear on your starter, battery, solenoids, etc...Is the wear and tear on these components worth the slight extra mpg that you are going to get? You will pay for the extra mpg, by replacing these components earlier than you would have with my pulse and glide method.

The technique you describe is "pulse-and-DFCO", which underperforms pulse-and-glide. Spinning the engine during DFCO takes energy, and you slow down much faster than you would in neutral. Because P&G allows much longer glides, it's more practical so you can use it more often, and your car uses less energy per mile for more mpg.

I think you can have three versions of pulse and glide:

1. Pulse and glide while shutting off the engine. This gets you the most fuel saving, but it is dangerous and it puts huge wear and tear on your starter/solenoid components. You pay for the fuel savings, by changing parts earleir than you would.

2. Pulse and glide in neutral. That gets you fuel savings, but keeps the AFR at stoich while in gliding. So your still wasting fuel. It also puts more stress on the shifting linkage, clutch, tranny. They are not going to fail, but there performance gets degraded over time.

3. Pulse and DFCO, as you put it. This shuts down your injectors and makes the AFR 20.xx:1 which is leaner than stoich and should get you better gas mileage than method 2. The car does slow down faster than method 2, but you have less wear and tear on the tranny, linkage and clutch. So from the cost prespective, it method 2 and 3 might end up the same.

IMO, method three is the safest, does not put as much strain on the starter/solenoid, tranny, clutch, shift linkeage as the other two methods and that saves money as well. It might not get you the best gas mileage, but it has its advantages over the other two.

BTW, your AFR should approach infinity, as you've got clean atmospheric air being pumped through the engine, and almost no combustion products mixed with it.

The gauge is limited to 20.xx. I know it is infinity.

[Mifunego]

Originally Posted by RobertSmalls

The engine by itself would be most efficient at full throttle, but most ECU's will enrich the mixture once you pass, oh, 3/4 throttle. As to how I accelerate slowly, well, even the 2.2L Subaru with its nice flat torque curve doesn't make much power at 1500-2200RPM. And my 1.0L Honda engine is even better.

How low can you go without lugging the engine? Do that, at full throttle.

Robert,

I'm guessing that this method works best in a non-turbocharged engine. Of course there is a difficulty with opening up the throttle so much without spooling up the turbo and occasionally hitting boost stage. I think my mpg on the most recent tank, trying the above method backs that up, as I have dropped to a 25.13. And while that is still better than EPA, it is not as good as I can get. Whether it is due to the use of the turbo or my application of this method is another question. FWIW, I have also been shutting down at stoplights, when appropriate.

Of course, if the 2.2L you're talking about is force-fed also, then it's probably my technique.

Regarding coasting and shut down, I agree with nj1266 about the potential hazards of turning off the car in traffic. I coast in neutral when I can, although living and driving in a city like Chicago can make that a challenge. I also shut off the car when I know I'll be waiting more than just a moment or two at a stoplight (not well defined I know, but that is a play-it-by-ear type of call). I'm not saying it can't be done, I personally am not comfortable with it.

[Dean in Milwaukee]

I'm suprised your not getting better mpg.

I have a manual shift 06 mazda 5 with the non turbo version of the same 2.3 you have, in a even bigger and heavier car. Despite this, my worst tank ever is around 26 and normally I see more like 28 or 29 around town with 30-32 on hwy trips.

All I do to get these numbers on the hwy is use the cruise control and don't speed, and around town I acclerate briskly but short shift, ( as much as I can without lugging the motor) and again no speeding.

I am unsure why you car doesn't do better, it sounds like your doing everything right.