yep, these motors are made for higher revs, and require higher rpms to run properly, 3500 - 4500 is optimal in these motors, thats why what little power they have is made at 5600 rpm

 

My concern is that if the problem is because of a bad ECU, if its noting throwing a CEL, they will just assume its because of how I drive, and won't want to replace anything.

 

Warming up the engine before driving will make your MPG worse. It will greatly increase the time required for the engine to warm up, extend the time the engine is running on a cold rich idle mixture, wasting gas while going no miles.
I watch my engine temperature rise on my ScanGauge. Idling in the driveway can take 10 minutes to reach 185F, but it will only take 5 minutes of gentle driving. Better to warm up while driving, like the manual recommends.

 

I find I get the best mpg by using the least rpms and the least throttle neccessary. I leave one gear at 2000 rpm and enter the next gear at 1500 rpm, using light throttle. 5th gear comes at 40 mph. Also I don't spend a lot of time over 65 mph. That driving resulting in 35 mpg for 3,000 miles of driving around town, and 35 mpg on a 3000-mile trip around the Eastern US.
High rpms use more gas. If you want to loaf along at 40 mph under no load, you will use less gas in 5th at 2000 rpm than in 4th or 3rd at higher rpms.

Often when people see mention of 1500 or 2000 rpm, they mention lugging. I avoid lugging, which is felt as a shuddering. I have never felt the VVT xB lug. It pulls smoothly from a rolling start in 2nd, and at 1500 rpm in 5th, if gentle throttle is used. I have a older 4-cylinder 2.6L truck without VVT and it will lug under those conditions.

 

[quote="vintage42"]Higher RPM's use more gas? Says who? Pushing the throttle in further uses more gas. You have to push the throttle in further to get going if you're in a lower gear. I have done both these things with my ScanGauge II. I have run 2 full tanks of gas shifting early and running lower RPM's and 2 full tanks shifting later and running higher RPM's. I averaged 30 MPG shifting later and reving higher and only 27 shifting earlier and reving lower.

 

With each revolution, gas is injected. The ECU only injects what can be burned. The more the RPMs, the more gas is injected and burned. You can burn a lot of gas at 60 mph in 3rd gear. As I said, "If you want to loaf along at 40 mph under no load, you will use less gas in 5th at 2000 rpm than in 4th or 3rd at higher rpms." Here is my ScanGuage: http://s49.photobucket.com/albums/f2...B%20ScanGuage/

I find I get the best mpg by using the least rpms and the least throttle neccessary for whatever speed I wish to hold. If the engine is not holdiing RPMs in one gear, then that is the signal to downshift to a lower gear.

The tradeoff between throttle and revs is most apparent with my 4-cyl truck pulling a 2000 lb boat and trailer. When 5th gear is no longer capable of holding a speed wth more throttle, it is time to downshift to 4th and let the engine spin at less throttle.

 

Yes, even with no load turning more RPM burns more gas in the same amount of time.

Forget the fancy electronic gadgets and just look at it logically.

How did I set idle speed in my '55 Chevy? By turning the idle screw. What did that do? Increased or decreased the amount of fuel supplied in a given time. To idle at a higher speed one had to put in more gas.

Let's just put ANY car in neutral and let it idle. To run that engine at more RPM, what does on do? Right! One steps on the gas.

If one needs electronic confirmation, normal warm idle on my xB is 0.2 GPH per my ScanGauge II. Cold idle, at a higgher RPM is 0.3 or 0.4 GPH. If I want the engine to turn faster, all I need to do is step on the gas - and watch the GPH increase.

Now, finally, lets put the car on the road and run it comfortably in 4th at, say, 1500 RPM on flat ground. Look at the GPH and/or MPG. Make the same run, same speed, in 3rd and note the GPH and/or MPG. It's higher.

(The biggest change one can make to improve their fuel mileage is to accelerate more gently and to hold speeds more evenly.)

Hope there is some way to verify your vehicle is using more fuel than it should be, for reasons other than driving style. Actually, if more fuel is being dumped in than the engine can use it will be cooking the catalytic converter and still some will likely come out the tailpipe and screw up emissions.

 

Yep. You'll burn more fuel on flat level roads at constant speed using a higher RPM. But you'll get better average MPG at higher RPMs because you don't have the huge MPG drop at the slightest hill, headwind, or when accelerating. ~3,000 RPM seems to be the sweet spot- decent power and mileage.

You can get great MPG putzing along at low RPM in a high gear while feathering the throttle with eyes glued to a ScanGauge, but that doesn't sound like fun and not how most people drive.

Max torque is at 4,000 RPM, max HP is 6,000 RPM. You're SUPPOSED to rev this engine! And MOST people will get better mileage if they do.

 

I live in Utah and obviously the roads aren't flat here. I have been experimenting with my driving styles for awhile now. I have personally found that for my driving situations, I get the best MPG when I stick to around 3000-3500 RPM's. I have 18" rims, intake, and exhaust and am averaging 30 MPG. Not only that I don't drive slow. I get on it quite often and still average 30 MPG. With my stock steelies on I was getting 32 MPG. So I gues you could say that my driving style is working for me and that's all that matters. It's obviously not going to work for everyone.

 

Ok, Vehicle is at the dealership, dropped it off around 7:15 this morning. Will update when I know more today.

 

Just picked up vehicle. They say that there is no problem with my car. They supposebly topped off my tank, and then drove 20 miles, went back to the same gas station, toppped off the tank again, and put a half gallon in the car to fill it up.

They drove 20 miles at 2000 RPM and that is a "fuel consumption test". If they continued driving like that, it means the xB would of been getting 40 miles per gallon. I think thats a load of crap. Ive never got that before.

 

Well, you certainly could reproduce it yourself and see what you get.

What I find amazing, is that's their way of testing fuel consumption? Very high tech! Good thing a 'dealership' did it for you, because a regular mechanic might have found the procedure too advanced...

 

It proves that your xB is capable of the same good mileage that mine is. I have an '06 5-speed and have recorded each tank for the past 12,000 miles. The best tanks were 42.8, 40.0, 37.2, 37.1, and many from 36 to 34.

My tanks of 40 mpg were done by steady cruising at moderate speed, but not as moderate as 2000 RPM (40 mph in 5th)! If I could do a tank at a steady 40 mph I am sure the mpg would rise to 45.

I do know what it takes to get low mpg. When I arrived at Lexington OH for Exposed 06, I filled up at the beginning and end of the day. The car went 19 miles that day and got 23.8 mpg. Those miles were spent in traffic around Lexington and the Mid-Ohio venue, in puttering around the grounds and infield, and in several full throttle laps around the racetrack.

So my xB gets anywhere from 43.8 to 23.8 mpg, and it's due to how it's driven.

 

[quote="vintage42"]If you look earlier in this thread you'll see I was getting 17 mpg on my first few tanks. I did let the wife take the car on my last tank, and get some highway miles on it for like 2 days (tank lasted about 2 weeks). Just filled up yesterday, so that past tank I got 23 mpg...

 

I would find a local club (through SL) and see if you can find a local xB owner willing to trade cars with you for a couple of weeks. See if the poor fuel economy stays with the car or with the driver...

R

 

One thing I have just noticed from another thread here is it seems another's xB automatic for some reason isn't shifting into 4th gear (overdrive). When you are driving along at over 40 MPH, could you note your RPM and report it?

AUTOMATIC:

2560 RPM @ 60 MPH
2990 RPM @ 70 MPH
3410 RPM @ 80 MPH

(That would mean about 1700 at 40 MPH...)

Tom

 

Well, I dont have a scanguage so I wont be able to get as accurate as that, but after I get off work today, I will write it down, and report back. Thanks!

 

The VVT engine is made for low RPMS, too. This engine pulls better at 1500 RPM than my much larger 4-cylinder truck which does not have VVT.
I spend a lot of time at 2,000 RPM. That's where I shift and where I cruise around town. My overall average for the last 8,000 miles, including winter driving in northern KY, has been 32.4 MPG. The average was 35 MPG until 3,000 miles of winter at 30 MPG reduced it.
I very rarely do the 80 mph that 4000 RPM requires, and have never seen 4500 RPM in 5th gear.

 

I'm sorry, I had to respond to this thread as I experienced a similar event with my old 2000 Civic Si after it drove through 2 feet of water(w/o stalling). Afterwards my mpg suffered and they performed nearly the identical useless gas consumption test:

the service manager drove it...ALL THE WAY HOME AND BACK THE NEXT DAY! A whole 26 mile round trip and returned with a 44mpg rating for my '00 Si, lol. He probably topped it off and then filled the filler tube as well. It was getting 19-22 when it always got 25-28(overnight loss after flood = obvious conclusion).

This same idiot sat in astonishment as I told him I check my mpg every time I fill up. In utter disbelief he asked how the hell I performed this task. Wide eyed and eager to hear my simple explanation of filling and dividing miles by gallons, what a shocker.

Anyway, after 3 visits including a second dealership shop, they concluded my missing mpg was due to carbon buildup in the engine and not covered under the insurance claim. Despite the obvious fact that it wasn't present prior to the flood or the mpg would have been bad then.

Current RSX when it got low mpg was a bad o2 sensor. CEL didn't come on until many weeks later. So yours could still be the o2, just that it hasn't reached the minimum specification for failing yet.

 

Mine is (are actually) the same way. Both of them; an 05 & an 06. Strangest thing.

krustytheclown: Good luck figuring out your troubles.