Increase gas mileage 20%

[gary350]

I have increased my gas mileage about 20% with a 1k ohm resistor on my Chevy Tahoe.

My gas mileage started going down and getting worse 13 mpg in town is bad, I decided to do my own investigation to figure out what is wrong.

First thing I noticed is the heater does not get very warm anymore in the winter so I bought a new cooling system thermostat. I put the new and old thermostat in a pan of water and placed it on the kitchen stove. The old thermostat opened at 135 degrees F and the new thermostat opens at 195 like it should. I put the new thermostat in the engine drove out a full tank of gas and the mileage is up to 16 mpg.

Next I decided the engine has 67k miles maybe it needs new spark plugs. The new spark plugs brought gas mileage up to 18 mpg.

I took a trip to Colorado, I checked my gas mileage every time I filled the tank with gas. Mileage was holding good all the way there but after I drove up to high elevation 12,ooo. and 16,000. feet my gas mileage was way up 21.5 mpg.

My Son graduated from automotive technical top of his class 3 years ago so I ask him about it. Air at high elevation has less oxygen the computer tells the engine to burn less fuel so you get better gas mileage. Any thing you can do to the engine to make it run hotter or make the computer think it is running hotter will give you better gas mileage. Any thing you can do to the engine to make the computer think it is sucking in less oxygen will give you better gas mileage.

I went to Auto Zone and bought 5 engine temperature sensors. I checked the ohm value and they were within 5% plus and minus. I replaced the sensor with the lowest ohm reading and my gas mileage was up about 1/2 mpg. I had already bought a new temperature sensor so I returned it with the other 4 sensors for a refund.

Next I bought 5 air temperature sensors they are all within 5% plus or minus so I used the lowest ohm value and returned 5 for a refund. Gas mileage is up another 1/2 mpg. Gas mileage is up to 19.

Next I replaced the air temperature sensor with a 1k ohm resistor this makes the computer think the engine is sucking is 150 air all the time. Gas mileage is up, 24 mpg in town and 29 on the highway.

For a year every time I filled the gas tank I checked gas mileage and removed all the sparks plugs to see if they were running too hot. 40,000. miles later I am still getting excellent gas mileage and all is well.

Here is a photo if the 1k resistor. Pull the plug from the air sensor and insert the resistor.

You need to check ohms of the air sensor in your vehicle, all vehicles are not the same.

As I recall my air sensor is for an air temperature range of about -50 deg to 125 deg F. I did google search to fine the range for ohms it was about 2000 ohms for -50 and about 1200 ohms for 125 degrees. 1000 ohms is just enough to compensate for old oxygen sensors that are no longer working properly.

 

[killivolt]

Think it would work on my 92 Buick Lesabre ?

kv

Edit: Oh, ya. Like the bread tie.

 

[audioguru]

Running too lean might save a little gas but it is a great way to kill an engine. It also kills the catalytic converter then the engine pollutes (stinking NOx).

 

[gary350]

What happens with most vehicles the oxygen sensor or sensors slowly go bad and the engine starts to run rich with age and you get poor gas mileage. You can replace the oxygen sensor yourself and test them your self they cost about $120 at Auto Zone and O Riley auto parts but will cost you $400 at the dealer. Some dealers refuse to sell they the only way you can get a new oxygen sensor is pay the dealer $300 to install it. Your engine is running too rich so you have several choices spend $700 to get it fixed, spend $150 fix it yourself or spend 10 cents for a resistor to trick the computer into running leaner. Example, oxygen sensors might be making the vehicle run a 12 to 1 air/fuel ratio that is why vehicle fail emission tests. Trick the computer into running leaner now it runs at 14 or 15 to 1 much better than before without replacing oxygen sensors. Target is 15.2 to 1 so the 1k resistor is not making the motor run too lean it is only making it run leaner than it has been running.

I took my vehicle to a friend that owns an auto repair shop we used his emission tester to experiment with my exhaust. I tried several resistors in place of the air temperature sensor to get correct ohms that was needed to get in the correct emission range. Anything in a certain range lean or rich range will pass emission test. You don't want to get too lean it will make the engine run hot that is why I inspected my sparks plugs after ever fuel tank fill up. If spark plugs look white the engine is too lean. If spark plugs look black it is too rich. If they look gray that is a good indicator fuel/air mix is good.

 

[audioguru]

An ordinary catalytic converter burns fuel (HC) in the exhaust that did not get burned in the engine. When an engine is suddenly accelerated then it is rich (lots of HC) for a moment or when the O2 sensor is old then the Cat cleans it up. But running lean produces the awful pollutant Nitrous Oxide that an ordinary Cat passes into the atmosphere because the O2 sensor and car's computer are supposed to adjust the air/fuel ratio to prevent it. Sometimes when an engine runs lean it is so starved for fuel that it tries to use the pistons, valves and spark plugs for fuel (melts them). Think about what happens to the important film of oil on the cylinder walls. The "check engine" light should come on.

They changed the emissions test here, they don't test anything anymore. Now they simply use their computer to ask the car's computer how well has it been running. Then they will spot your trick resistor instantly.

 

[shortbus=]

On older cars many times the oxygen sensor will throw a code, saying they are bad. But before replacing the sensor look at it. The area where the wires go into it should be clean. No oil or road junk on it. By road junk I mean dirt. There are small vents in this area of the sensor that have to allow outside air into the sensor, to make it work properly. This is called, "reference air", and is what makes the sensor give the signal it's supposed too. If the vents are clogged, theres no reference air and no or incorrect signal sent to the ECM, this sets a oxy sensor code.

Many older cars leak oil or even antifreeze, if this gets on the sensor it plugs the vents and sensors get replaced when they could still be good. My '99 S10 4x4 had mud on the sensor, cleaned it of with a hand held wire brush and it hasn't set a new code since. https://www.ngk.com.au/oxygen-sensors/technical-information/how-does-the-oxygen-sensor-work

 

[gary350]

Yes you can clean up your own oxygen sensors and make them work better. There are good instructions online. You can buy a new sensor and compare the new one to the old one to see if the old one is working and how well is it working. My engine has 2 oxygen sensors, 1 before the catalytic converter and 1 after the catalytic converter. There are also 2 different types of oxygen sensors. As long as your air/fuel ratio is 15.2 to 1 all is well. Someone needs to invent an after market detector you can install with a gauge on the dash that tells you the air/fuel ratio then you know if something needs to be fixed before you waste a lot of money on fuel.

 

[audioguru]

Some cars with a turbo boosted engine have a gauge that tells if the mixture is rich or lean. It gets too lean if the fuel pump doesn't pump hard enough and gets too rich if the air filter is dirty.

 

[MikeMl]

My Cessna has a six cylinder engine, with six Exhaust Gas Temperature (EGT) probes, one per cylinder. Mixture control is manual, so I can enrichen or lean to keep the EGTs near maximum, which is best fuel economy, but slightly less than maximum available power.