High altitude - what about boosting input pressure?

We live in the mile high city - the greater Denver area.
There's about 12% less oxygen and air pressure here and I understand that
cars get about that much less gas mileage because of it?
The tail pipe sure is black, I know that's not an objective standard or anything.
But we have this 93 Corolla and were wondering of a low cost air blower could be added before the air filter, so that it would regulate the input air pressure to that of sea level?
Can that be done cost effectively?
We sure wouldn't mind saving 12% on gas, if it didn't cost much to do.
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Oh...just loosen your shoes a little. You'll be more comfortable.
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Moon Goddess wrote:

What you are talking about in essence is a "poor man's" supercharger / turbocharger. You will be boosting the ambient air pressure. This plan will eventually take it's toll on engine components that are not designed for any boost and substantially reduce your engine's life. Do you have a plan for any controls for the system to control the boost pressure? A better plan for you is to take the car to the dealer and have them re jet the carburetor to your driving environment. This is a normal problem and they are usually quite well versed in this adjustment and probably do it very accurately. If the 93 Corolla has fuel injection, you obviously have a problem with it as you mentioned the exhaust pipe is black. Many people have move from one local to the other, experienced this condition, and have had to have this adjustment performed on carbureted vehicles. Your engine will thank you, and you will be rewarded with fuel savings, and better performance.
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How are they not designed for sea level. That's all I'm talking about.

I wasn't sure if there were kits that would just regulate it to sea level pressure.

EFI, no carb.

Yes, 12% less oxygen seems to be the problem.

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Moon Goddess wrote:

If you have the EFI system, it will automatically compensate for any altitude and or barometric pressure changes, and adjust the fuel to maintain a perfect air to fuel ratio (14.7 : 1). You need to take your car in for service.
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understand
standard
not
about.
had
engine
But I'm getting 25-30 MPG. It's done the black tailpipe thing since we had 45k miles on it when we bought it. It now has 152k.
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Moon Goddess wrote:

If you have had black deposits in the exhaust system for that long, the catalytic converter may be ruined, the O2 sensor(s) are probably coated (coked up) with carbon and your engine is not performing as it should. My advice to you IMHO, would be to take the car in to a reputable Toyota dealer and have them troubleshoot the problem. You definitely have something wrong with the engine. It is not normal to observe black carbon deposits on the inside of the exhaust system, which usually indicate a rich (too much fuel) condition. With the EFI system, it should run flawlessly at any terrestrial ambient condition. If you have this problem repaired your MPG should improve even from what you get now.
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Not necessarily, this is high altitude, maybe it just runs rich the whole life of the car.
It still exceeds by double, the emissions standards, sometimes by triple.

Yeah, high altitude dude.

Like at 12000 feet? Come on.

Or I could waste a lot of money for nothing.
It still gets the same 25-30 mpg at 152000 miles as when we got it at 45000 miles. It still passes emissions tests by at least 2-3x the limits.
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I have driven across Trail Ridge Rd in Rocky Mountain National Park many times without any noticeable problem. The altitude is 12000 feet. Once I drove a car up to the top of Mount Evens at 14000 ft, although I was traveling a pretty slow speed, so I don't know if that is fair test.
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What I'm saying is that the less oxygen there is, the more of that black tailpipe you'll see.
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This is true if the amount of fuel delivered to the engine is constant because the air/fuel mixture will become rich, i.e., too much fuel relative to the amount of oxygen.
Your vehicle has a sensor that determines how much air is entering the engine and will adjust the amount of fuel to maintain the correct air/fuel mixture.
It is normal for the inside of the exhaust pipe to become black over time. While the emissions controls do a pretty good job of removing tailpipe emissions, they do not remove all of them. Mixed in with the exhaust gases are hydrocarbons, which are unburnt fuel in the form of particulates, or soot. The particulates eventually coat the inside of the exhaust pipe, giving it a black appearance.
If your engine was running rich, your car would not pass any periodic emissions test. Assuming that your car has passed emissions tests, then the electronic fuel injection system is functioning properly.
As an aside, if you were to add additional intake air through the use of a fan, turbocharger, or supercharger, the engine control module will sense the additional air and command additional fuel, so although your car's performance may improve, your fuel economy may get worse unless you are very careful to apply less throttle.
--

Ray O
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"Ray O" <rokigawaATtristarassociatesDOTcom> wrote :

Does that need any special adjustment for the altitude?
Is there a way that I can lean that setting out but adjusting it?

Oh ok.

Like I said, not only passed them but 2-3 times at least, the standards.

I see.
Here's another question;
Back during the oil & gas crisis of the 70's, people were adding vacuum gauges to their cars. It would be mounted behind the steering wheel on the dash.
They had green, yellow and red zones, so you could lighten up your foot and get better MPG.
Is there any point in using something like that nowdays? Do they still sell them for that?
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<snipped>

Back when engines had carburetors, you could change the carburetor jets for high altitude applications to maintain the proper air/fuel mixture of 14.7 parts air to 1 part fuel. A modern fuel injection system, which your Corolla has, does this by controlling how long the fuel injector sprays fuel, so at higher altitudes, the injector sprays less fuel than at sea level for a given throttle position.
There is no way for you to lean out the setting because there is no need to. The system is programmed to maintain the 14.7:1 air/fuel ratio, which supports complete combustion of the fuel. If you were to lean the adjustment to, say, 16:1, the fuel would not burn as completely so you would be wasting fuel by sending unburnt fuel out the exhaust, and to make things worse, you would have to depress the throttle more for a given amount of acceleration or cruising, so fuel economy would go down even more.
If your goal is to improve fuel economy, then modifying the air/fuel ratio is not the answer because doing so will make fuel economy worse.
If your goal is to improve fuel economy, then the same things that work at sea level will work at altitude. Try these simple things that many people overlook:
1) Use either Denso or NGK brand spark plugs, ignition wires, distributor rotor, and distributor cap that are recommended for your car and stay away from other brands. Some other brands may work fine, but many do not so rather than experiment, stick to Denso or NGK.
2) Check ignition timing to make sure it is within factory specifications, probably around 10 degrees before top dead center.
3) Make sure the engine air filter is clean.
4) Rather than buying the cheapest gas you can find, stick to a name brand and buy from a gas station that does a good sales volume to reduce the chances of sediment getting into your fuel system.
5) Inflate your tires to 5 PSI over the automaker's recommended tire pressure. This will improve tread life and improve fuel economy by reducing rolling resistance, with a slightly harsher ride.
6) Remove all unnecessary payload from the vehicle because the engine has to work to move that payload around. Even 50 extra pounds in the trunk can make a 1/4 to 1/2 MPG difference.
7) Make sure the engine thermostat opens at the proper temperature. If the thermostat is stuck open, missing, or opens at the incorrect temperature, the engine will take longer to warm up, and if the engine takes longer to warm up, it will run rich for a longer time.

A huge side benefit from a clean running engine is a very efficient engine. Mess with the engine and efficiency will probably be lost.

The principles behind using a vacuum gauge have not changed, so I suppose you could still add a vacuum gauge. I think most people could learn to drive more efficiently just by listening to the engine and changing their driving habits. The drawback to a vacuum gauge is that you are adding a potential source for a vacuum leak, which would hurt fuel economy.
Turn off any unnecessary electrical accessories like TV's, video games, unneeded fog lights, etc. and use the AC sparingly, if at all.
If your car has an automatic transmission, the sooner you back off the throttle, the sooner the transmission will upshift, and the sooner the transmission upshifts, the better the fuel mileage. When accelerating while the car is already cruising, depressing the throttle gradually will reduce downshifts. The adage that you can improve fuel economy by driving as if there is an egg between your foot and the gas pedal is true.
Lots of short trips where the engine has to warm up will hurt fuel economy, as will idling the engine for long periods. If the engine has to idle for more than a minute and you are not at a traffic intersection, shut it off.
The fuel economy that you posted is pretty good for a 14 year old car, especially at altitude. I would try the stuff I listed above and drive like the egg is there, and you may see a 1 or 2 MPG gain.
--

Ray O
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"Ray O" <rokigawaATtristarassociatesDOTcom> wrote :
...

OK.
I thought that was all electronic now, didn't even know it could be changed. It can?

Good one. I let that go too long last time and the MPG started going down along with performance.
...

Remote though.

Ok thanks!
Oh, finding a vacuum gauge nowdays ain't gonna be easy. They don't make them like that anymore, I guess. Here's an old one though: http://tinyurl.com/2r662b
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Ignition timing cannot be manually adjusted on a vehicle with a distributor-less ignition, but if the car has a distributor ( IIRC the 1993 Corolla has a distributor), then timing can be adjusted.
Timing is kind of adjustable on some engines with a distributor-less ignition by adjusting with the crankshaft position sensor.

Vacuum gauges have fallen out of favor with consumers because it is very easy to learn how to drive to maximize fuel economy without one. If you really want a vacuum gauge, you can get a diagnostic one and snake it into the passenger compartment and use it until you get the hang of driving without it, then put the gauge away in your toolbox.
--

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"Ray O" <rokigawaATtristarassociatesDOTcom> wrote :

Does it have points that need replacing too?
I thought it was all electronically done in this model.

Hmm.
It looks like they may even still sell them, but they have no photos there: http://www.stewartwarner.com/catalog/mchvac.html
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Your car does not have points or a condenser, which is why I did not mention them under #1 above. The function of the points and condenser is handled electronically by the igniter (which does not need routine replacement).

I knew you could still get vacuum gauges, although I don't really see a reason to install one unless the driver is not disciplined enough to drive with a light foot.
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And your car monitors the current environmental conditions among other things as you drive and constantly keeps the engine running properly.
In other words the car is smart enough to know when you drive up a mountain and changes all the engine controls automatically for you.
Dan
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Moon Goddess wrote:

Not with a correctly functioning EFI system. All consumer fuel injection systems are designed to adjust the fuel air ratio to perfect stoichiometry for gasoline.

Then your engine is performing at normal standards, that is good.

Perhaps a bit, but nothing abundant, and as you mentioned, it passes emissions.

No, it really does. They are designed and tested to do so.

Or, waste a lot of money on some after market rigged system that isn't going to address your problems.

You may want to consider selling it and buying something that is more suited to the power and MPG targets you are looking for, perhaps a car that is supercharged or turbocharged. But, of course, it's your call.

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That's pretty funny. But your engine should run perfectly regardless of the altitude or temperature.
If not then chances are maintenance and/or repairs were not done properly.
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