My own testing and experience have confirmed this for my VW. I suspect it's true for other vehicles too.

It seems that lean burn is better than optimizing for BSFC and reduced pumping losses, and those with cars so equipped maybe should utilize it instead.

Stop guessing. Hook up a meter. The link is in my sig. In my vehicles, at a given RPM, there's barely any difference in fuel usage between 1/4 throttle and WOT at any given RPM. If I'm at 2000rpm with 1/4 throttle, and I go to 1/2 or fullly open throttle, fuel usage barely goes up (except to follow RPM), but power definitely DOES go up.

Oddly, in my VW, 80 or 90% throttle uses MORE fuel than 100%.

Lean burn is the difference.

Just read my log. But I only have 3 entries. I have been trying to get the max MPG, but have only started logging my MPG online just recently. I am the slowest guy on the road usually, but I am driving for max MPG. I drive by the Scanguage, and yes it will change the way you drive. You learn so much by it - where the optimal MPG speed is at, how coasting and gliding in neutral saves fuel vice just downshifting or allowing the engine to use compression braking.

It's hard to believe that a device that reads instantaneous MPG readout, along with "current" trip, "today", "previous" and "tank" MPG readouts can actually change the way you drive, but it can. You have to have patience and the willingness to change your habits, as well as the "want" to actually get the best MPG possible.

I am also on ecomodder.com

99metro

As you probably realize, I have lean burn, but what I see is nevertheless very similar to what you described (i.e., with regard to the comparison between light throttle and heavy throttle). So in my view there's still some mystery here, and a need for more testing and data analysis.

In my case, it's pretty clear. I've been testing both high and low throttle for accelerating from a stop, over the last several months. No "proper" testing, but daily driving, trying one today and the other tomorrow. All the while, I'm using heavy-throttle P&G once I'm up to speed.

From a stop, lighter throttle is better. Heavy throttle comes into play at higher speeds, in a P&G routine. As I said in another thread, it makes the difference between low 60's mpg for heavy throttle, and upper 60's to low 70's mpg with light throttle.

PaleMalenesian: when you say up to speed, how is up to speed?

My commute is about 50-50 split with 55 limit and 45 limit. By "up to speed", I mean maybe 40mph in 5th, maybe 45. I use this for the 55-limit segment as well. There are 3 lanes and plenty of room for others to pass. I sometimes go to 40, do a mini-glide to 35, and then PULSE from there to begin my P&G routine.

I must be missing something. How can you have more power but "barely use more fuel?"

I know you are using your injector duty cycle gauge ... is the fuel pressure constant or does it vary with throttle angle?

In other words, I could understand small changes in duty cycle contributing to large power changes IF the fuel pressure were also changing accordingly.

Well, I was under the impression that fuel ratio pressure is constant.

The thing is, A/F ratio has to remain approximately constant. So, given the same RPM and normal aspiration, it's only going to pull in so much air. As the throttle opens, it doesn't try to get more air; it only gets more air because it's no longer restricted and is pumping more efficiently. The fuel injectors merely follow the amount of air requested.

I may have given the wrong impression. If 1/4 throttle is enough for cruising, 1/2 or 3/4 throttle doesn't throw me back into my seat with my cheeks stretching back behind my head. It just gives me definite acceleration, while usually observing an unexpectedly minor change in injector duty cycle.

Now, the observation that I can't even begin to explain is why WOT actually uses less fuel than 85% throttle while still producing more power. Must be some kind of lean burn. O2 sensor readings aren't as consistent as FI duty cycle readings on this issue, though sometimes they show lean mixture for it. I guess I have to look over the logs more.

Generally speaking adding 50% more fuel with throttle at 80& gives you 150% more power.

regards
gary

I was just thinking about the WOT remarks and, to me, it makes sense that perhaps at 80% throttle the car is injecting 100% of it's fuel potential, so the injectors are maxed at 80% throttle... WOT would then give you 20% more air to mix that with...? More air = more power, we all know that.

Did I make any sense?

sorry to bring this back from the dead... but I did get 30 mpg again!! 3 fillups in a row... and the scangauge is supposed to be sitting at my door this afternoon when I get home, so that means I'll be fabbing a trail HAI as well as grill block and hoping to see some 32-33mpg fillups soon.

Keep at it. You'll get your 33mpg!

Forgive me for bragging, but my '99 V6 Grand Am with automatic got over 37 mpg for the second full tank in a row. That puts my mileage over the last 90 days to well over 35 mpg, which is 76% over EPA. No big secret here: Taking care of the car, keping tires inflated, driving like I have an egg under my right foot, not worrying about what other drivers think. Great mileage in an "everyman's car" is possible!

Nice job you guys! Very impressive numbers!
This really highlights that all it really takes is some knowledge and dedicated practice. Hints from others, coaching and more practice.

Good work, keep it up. And pass the word to those you come in contact with. This is something everyone can use, why not share it?

Offer to coach your spouse (could be risky) or a friend or aquaintance. Keeps your skills up.

I got 50.6 mpg before i found this website. That was for one trip of 104 miles. What i did was turn off engine when stopped, use cruise control (62mph) and draft. No eoc. the major thing was that i drafted at about 20 feet in back of the truck. The trucks were going 55 or 60. Now i draft much further back and use eoc. I use my car much more now because of the price of fuel so it doubles as a van. On using the gas peddle i use the technique i was taught at rev it up. It has to do with how an engine makes power. Now is use the heel and toe and just gently extend my foot from the ankle joint and then engine is much more responsive. I saw graphs of power bands for engines and how manufacturers tune it for the most use but not the most efficient. I try to go upto 2000 rpms, skip up to 3000 rpms as quickly as possible. I don't want to be between 2000 and 3000 rpm. Cruising at 57 to 60 i am about 2600 to 2800 rpms, when drafting it gos down to 2300 to 2400 rpm. When they did the 106 mpg or so they chose to p and g from 33 to 40 mph on the closed course with their hybrid. As you can see this is the real world with traffic, wind, bad roads, traffic jams, rain, snow, cold, hot and the list just goes on. What ever we get over the norm is a bonus and saves a few pennies.

If you would've read through other posts, you'd notice I referrence my g/f's car getting 28mpg average out of a 3.8L V6 in her heavy Grand Prix GT, as well as my parents car being a '92 Bonneville that hasn't seen routine maintenance or oil changes in probably 5 or 6 years, still getting 30+ mpg.

Saturns are notorious for blow by, as is noticed with my 1 quart of oil used per fill up (300 miles), drastically reduced power over the last few years, and alterred FE... to achieve 30's in this DOHC auto model w/ no mods and rather dull driving technique is an achievement I'm semi-proud of. The consistancy is what shows me I'm learning... and for that, I think its priceless!

...not to mention I'm only doing about 40 or 50 miles of interstate each tank, so those other 250 miles are < 10 mile trips, to/from work is 6 miles for me, hardly enough time to warm the engine.

Scangauge + HAI + grill block = high hopes of 33 average next tank.

Again bringing this up from the dead, but didn't feel the need for a new thread.

I must give a follow up to my post I am NOW getting above the 30's in my vehicle on a consistent basis, that is all with short 5 mi trips no hwy.

How is yours going Project?

Just check my gaslog!

I still drive generally 80% city (>6 miles to work) and then lots of mixed driving on weekends.

I've been nudging past the 30 mark on to 31 mpg average tanks, my last two fillups reflect a trip to Cleveland, OH and back to Northern KY... I nearly fainted when I calculated the 43mpg!!

My cooling issues are solved now too, thanks to being stranded while out for dinner and diagnosing a bad coolant temp sensor, the car now reads and UNDERSTANDS it is running at optimal temp of 195*F, just like the thermostat is rated.... my cooling fan even worked for the first time in YEARS once I replaced the ECTS.

Mileage should be moving on up....

I think if you don't have one, you should fab a nice HAI, I did a DIY write up on how I did mine. Cost roughly $13, it already paid for itself IMO.

Also, are your tires at max, or 50? Is your car having any problems? Possibly your coolant temp sensor is acting goofy which is typical of the S-series.

Your SOHC should be making 30+ pretty easily, it looks like your mileage is improving though, so congrats! Keep it up!

Saturns are notorious for blow by, as is noticed with my 1 quart of oil used per fill up (300 miles), drastically reduced power over the last few years, and alterred FE... to achieve 30's in this DOHC auto model w/ no mods and rather dull driving technique is an achievement I'm semi-proud of....QUOTE]



Are you using a PCV enhancer to remove the oil and other liquids from the blow by gasses. I have found that to help my mileage by appoximately 10-15% on both my '88 and '97 Escorts. I don't know whether it will help you or not, but it is an inexpensive mod you might try. If nothing else it will keep the engine cleaner.

Not yet, but I did buy a Husky air compressor filter a while back, just need the vacuum hoses and a fitting to get it hooked up....

I take it all back on account of me starting my own "trend" which I'm very pleased with.... :)

I also have a DOHC auto Saturn but unlike yours mine has to haul around close to 3500 pounds buying the scangauge was the best investment in FE even beating out the LRR tires. I went from 18mpg (6 mile commute and a lead foot) to an average of over 29.5 mpg before the scangauge. Now that I have a real time feedback I can see what TPS inputs result in best milage for a given speed.....this tank I'm looking at 33+ and no EOC.

Yeah, I stopped EOC, only really did it for one tank but it just didn't seem beneficial enough for me in my route to/from work to use it daily.

Basically all I've done it learn to drive differently, stiffer accell to 4th gear, then chug along at 40mph in city maintaining 4th gear in all possible circumstances, monitor the TPS and MPG as well as IAT and *Fwt and this is the result. Seems I'm getting 31.xx mixed now as opposed to 26/27, and my highway mileage is getting unreal as far as what I thought was possible.