Nunyabiz

Yes the place I take my car has a very good Lexus mechanic there, worked at a Lexus dealership on nothing but Lexus for 15 years.
They have a scanner there that is probably the best you can buy, cost $8000, tells you everything right down to the last time you farted in the driver seat and this guy is very good at deciphering every little thing.
I had just replaced one of the 02 censors you listed about 3 months ago and at the same time he cleaned out the throttle body and replaced (cant think of the name of it at the moment) part that checks the air flow that is in the line right after the air filter.

All in all this car seems to run great, its just that my MPG dropped from the 21-24 (around town) that I was getting down to now it stays right between 16.2-16.7 consistently.
The car was "supposed" to get 19mpg city to 27 hwy according to the estimated MPG from Lexus however when I bought the car (got it used 4 years ago with 50,000 miles on it) I immediately changed the oil to 0W30 Amsoil & changed the air filter to a K&N and I was getting 21-24 city and 28-31 Hwy.

I also feel this bad MPG crap has to be connected to the 02 censors because there really isn't anything else.

I just hate to have my Lexus getting the same MPG as my big, square box, tall with big tires Jeep, that just doesn't seem right.

GEORGE_JET

There is also the possibility that the injectors, or fuel regulator is causing this problem. It sounds like they have taken a reasonable approach to the problem. I would next check the fuel pressure, and then flow test the injectors. They should have a injector tester, which can test the injectors while they are on the car. The tester pulses the injectors one at a time, while they monitor the fuel pressure drop. By comparing the drop for each injector, they can tell if they are leaking or clogged.

Do you recall the approximate mileage that the O2 injector was replaced? Mechanics recomend they replace them around 60k, but typically you can run them considerably longer. If they fail much earlier, that could be a indication of another problem.

285exp

The 1999 ES was rated at 17 mpg city, so it sounds like you're getting exactly what it was rated for. If you were ever getting 21-24 in the city, then you had a very unusual example, and it has merely reverted to what it should be. I have a '97 and an '00, and they both get 17-18 in the city, 26-28 hwy, and 20 combined.

Nunyabiz

Well like I said earlier my 99' ES300 actually has a 2000 engine in it from the factory.
The 2000 ES300 was supposed to get 19/26.
Once I changed the oil to 100% synthetic 0W30 and the air filter to a K&N I was never getting less than 21-22 at the very worst no matter what gas nor time of year.
22-24 was common with 28-31 on the highway.
I got that mileage for 4 years straight.



I assume you mean the 02 "sensor"? the last one was replaced just a couple months ago, in fact has been replaced twice in the past year because apparently while I was having problems with the car starting, (it would start then die immediately unless I gave it lots of gas, then would have to rev it up several times before it would idle, did this for a few months and that turned out to be the throttle body was gummed up and needed to be cleaned)
Apparently doing that for several months fried the 02 sensor that was just replaced.
So there are maybe 3000 miles on the current one and the throttle body is clean as brand new.

My last tankful I got 17.22mpg which is a slight improvement but is still 4-5+mpg less than normal.

We really cant afford to do much of anything else right now so probably just going to have to let it go until march of 2010 Tax return time.
The car seems to be running smoothly just not efficiently.
In March we are changing the water pump, pulleys & belts which should have been done at 90,000 but will have to wait until March (probably have 106,000 on it by then).

maybe at that time will change the other 02 sensor and have the injectors checked.

thanks for all your ideas, much appreciated.

285exp

I know that the 2000 was originally rated at 19/26, but that was based on the old, unrealistically optimistic rating system. When adjusted to reflect the current system it is 17/24.

http://www.fueleconomy.gov/feg/calcu...model=ES%20300

Clearly, where and how you drive is going to have an impact on your actual mileage, but 17 city is right in line in what I'm getting in both my 1997 and 2000 ES's. If you were ever getting 22-24 in actual city driving, well count yourself fortunate for the time you had. If the mfg's thought they could get a 35% improvement in city mileage by simply using synthetic oil and a K&N filter you can bet your bottom dollar that they would both be standard equipment on all cars.

Nunyabiz

I have raised my gas mileage on every car I have owned since 1980 by using synthetic oil, so obviously car manufacturers don't care that much.

When I first got my old Jeep (a 95' Wrangler) I was getting 12-13mpg, I went with 10W30 Synthetic, pulled out the air restricter right in front of the air filter which I changed to a K&N, also changed all the gear lube to 100% synthetic. I now get 16-17mpg around town and 18-20 hwy.
that is about a 35% improvement in MPG doing nothing but changing to 100% synthetic and making it breath better.

Still the fact remains that my mileage on the same car, using the same gas, in the same town, with the same driving habits dropped between 4-5MPG in the past several months.
I'd just like to know what is causing that drop in MPG.

285exp

If getting 35% better fuel economy was as simple as using synthetic oil and a K&N, then all the car manufacturers could meet the new CAFE standards simply by specifying them for their vehicles. Since they are not, and instead are spending billions to revamp their entire product lines, it can be safely assumed that their benefits are not proven to be particularly significant.

As for what is causing your car to get the same mileage as everyone else, you might check to see if both O2 sensors have been changed, and have them refill the magic pixie dust reservoir.

Nunyabiz

Both sensors have not been changed just one twice this year.
have no idea why car manufactures don't recommend 100% synthetic, makes no sense actually.
It has given better gas mileage in every car I have ever owned, 4 cylinder VWs both stock and built, 6 cylinder V6 in a Ford Bronco, 6 cyl straight 6 in my Jeep, 8 cyl V8 in my old Dodge van, and the best percentage was in the Lexus. Of course the oil itself is a bit better now than it was many years also.

I would say the reason that AMERICAN auto manufacturers and others selling cars IN the USA use API standard as the reason to not recommend synthetic.
In the U.S., the American Petroleum Institute (API) adopts a one-size-fits-all standard for engine oils, but in Europe the Automotive Manufacturers Association (ACEA) sets multi-tier motor oil standards, taking into consideration the wide variety of engines on the market. Most European automakers also create their own specific standards, using ACEA standards as a starting point.
Most European cars recommend 100% synthetic and also the oil change interval I think is around 10,000 miles or more on average.

I would lay odds that cars sold in the USA have to use the BS API standard because OIL COMPANIES demand it to keep profits high.

Same reason several cars sold elsewhere get much better MPG than they same model does here probably.

Either way you can pretty much bet the reason has something to do with American oil company profits.

285exp

Sorry, but it's absurd to think that our bankrupt domestic auto builders would spend billions to completely redesign their product lines to meet the new CAFE standards when they could spend a couple of hundred bucks a car on synthetic lubricants and aftermarket air filters to do the same thing.

The reasons several cars sold elsewhere get much better mpg than the ones sold here are much easier to explain by differing emission and safety standards than by conspiracy theories about the evil oil companies denying us extra slippery oil.

Nunyabiz

To each his own.

but one proven fact is that those evil oil companies without any question bought the patent rights to the batteries used in the electric car "EV1" back in the mid 90s so that they could kill production of it.

Another proven fact about those evil oil companies is the fact the occupation of Iraq was based solely on bald faced lies in order for American oil companies to attain access to those Iraqi oil fields.

None of what you are saying btw addresses why American auto makers refuse to adopt the far superior synthetic oils & change intervals.

Why exactly do you think those mileage standards are so low here in the US?
Why do most European cars get FAR better mileage?

If you think that oil company's don't have any pull in the US government then you are seriously delusional and watch too much Fox News.

285exp

There may be no question that Chevron obtained control over the patents for large scale NiMh batteries, but it is not a "proven fact" that it was done in order to kill the EV1. It is a lot more plausible that they obtained the patents so that if and when truly mass production electric vehicles were produced that they would be the ones to profit. The range and power limitations of pure electric vehicles will ensure that there is no danger of EV's replacing petroleum fueled vehicles anytime soon, so they pose no danger to their evil capitalist scheme.

The only reason that GM sank a billion dollars into the EV1 program was the result of the EPA mandating 2% of cars sold be zero emission vehicles, and when that was later rescinded, there was no reason to continue to develop a vehicle that had limited appeal and that they would have to sell at a loss.

http://www.greencar.com/articles/5-t...eed-gm-ev1.php

http://blogs.edmunds.com/karl/2006/0...mon-sense.html

I'm sure you have a reputable source to "prove" this, otherwise it is an irrelevant political rant.

Oh heck, I don't know, maybe they don't think that the costs outweigh the benefits for their vehicles, or that Americans will shell out 3x the price for the stuff.

Because we have cheap fuel, and we demand that it stay that way. Regular gas in Germany is currently $7.20 a gallon. I suggest that if you want US consumers to start demanding fuel efficient and/or electric cars, you start lobbying your representatives to slap a $5 per gallon tax on motor fuels. Good luck with that.

Back to the political ranting again. Since you seem to think that this is some right wing thing, please tell me what the current administration is doing about those nasty oil companies.

Nunyabiz

You are obviously not worth wasting anymore time responding to, you are more than a bit delusional.

/ignore

285exp

http://www.youtube.com/watch?v=c4SJ0xR2_bQ

Nunyabiz

Think I found the gremlin stealing gas mileage from my ES300.
combination of several things it seems.

I was getting down to a flat 16mpg. (July August)
My tires were slightly under inflated 28-29PSI and air filter was dirty.
fixed that started getting about 17 and a little over.

Last fill up I finally got right at 18MPG to be exact it was 17.98.
The temperature dropped probably a good 10 degrees that whole week.
I also received an email from Costco about some class action lawsuit concerning their gas stations saying they are being sued to be made to put "automatic temperature correcting pumps" at their stations.
That started me thinking about gas being the main culprit.

I get my gas at Costco and have been for about 1 1/2 years since it opened.
My last fill up I happened to get it very early on a very cool morning and got an extra 1 MPG.

I also noticed that they started selling 10% Ethanol gas, the gas I used to get prior to Costco had zero Ethanol.

Unfortunately now I think that probably ALL the gas stations around here are selling 10% Ethanol blend.

Between the Ethanol blend and the pumps not correcting for temperature especially when its hot as hell here like well over 90 degrees is why my mileage dropped so dramatically.
The air filter, tire inflation made maybe a 1 1/2 MPG difference or so, the route my wife drives to work has also gotten MUCH more crowded in the last 1 1/2 to 2 years also so it is a lot more stop & go than it used to be, that probably accounts for a tiny bit.

The rest of it seems to be hot weather at a non temperature controlled pump that has started selling 10% blending Ethanol.

So blam, down from 21-24mpg to now about 18.
If I can find regular zero ethanol gas around I will check that to make absolutely certain but I am sure I would get around 21MPG or better if I do.

285exp

Fuel economy decreases by around .3% per psi underinflation. 3 lbs underinflated would only have a .2 mpg effect on a 20 mpg car.

Dirty air filters have no significant effect on the fuel economy of a fuel injected car.

http://fueleconomy.gov/feg/maintain.shtml

I don't know of any stations in the continental US that have temperature compensating pumps, so this effect is not unique to Costco. The time of day you refuel has no real effect, since the fuel is stored in underground tanks where the temperature is unaffected by daily temperature changes. Only the small amount of fuel in the pump itself will be significantly higher or lower than the fuel in the tank. A standard gallon of gas is measured at 60 degrees F, and you lose 1% for each 15 degrees above the standard temperature. Assuming that the fuel temperature got as high as 90 degrees, that's only a loss of 2%.

E10 has about 3% less BTU's than straight gasoline, so you can expect around a 3% decrease in fuel economy from using it. The few times I have used the stuff I found no significant change in mileage.

The increase in congestion of your wife's route is far more likely to be the cause of your decreased mileage, since the other factors you are blaming count for only around a 5% decrease. While stopped, you are getting exactly 0 mpg, and every you push either the gas or brake you are wasting fuel. Add the fuel wasted while sitting stopped in the car with the ac running, and the way you drive the car is affecting the mileage much more than tire pressure, air filter, fuel temperature, and ethanol.