Double your gas mileage almost or close to it.

[gary350]

I have been experementing with this for about a year. There are several things that can be don't to increase gas mileage but the thing that works best is to replace the air intake temperature sensor with a fixed resistor.

I removed my air intake temperature sensor and it tests 50K at 60 degrees F with my ohm meter. If I breath on the temperature sensor and warm up to 98.6 deg F the resistance changes to 20K. This link shows the temperature range. https://www.aa1car.com/library/air_temp_sensors.htm

Warm air = thin air so the engine needs less fuel. I unplugged the wire from the temperature sensor then I inserted a 10K resistor into the end of the wire. My 99 Chevy Tahoe plug is perfect of pushing the resistor wires right in the spring clip holes. The engine starts and runs fine gas mileage is up a little because the 10K resistor makes the engine computer think it is sicking in 130 deg F air thats about = to driving across Death Valley on a hot day.

I experemented with lower and lower resistors. Now I am using a 1K resistor. The engine starts fine in the summer but it is hard to start in the winter. If the engine won't start on an extreme cold day I plug in a 10K resistor drive to work or to the store about 5 minutes into the drive I pull over and swap the 10K for 1K. Restart the engine and continue driving. The 1K resistor makes the computer think it is sucking in 250 deg F air.

I did a lot of tests with 10K resistor, 5K resistor, 2K resistor now the 1K resistor. I been checking the engine, checking the spark plugs, checking the oil, I don't want to damage the engine by making it run too lean. With the 1K resistor if I punch the gas pedal to the floor the engine sounds like it is starving for fuel and it will not pick up speed. But if I slowely push the gas pedal I can still pick up speed quick and pass cars on the highway. You have to learn to drive without a heavy foot.

My gas mileage is up from 12 mpg in town to 23 mpg in town.

Next I need to connect a 10K variable resistor in series with a 1K resistor and mount it on the car dash with 2 wires going under the hood to the temperature sensor plug. Turn the 10K resistor up to 10K including the 1K in series resistance will be 11K and start the engine. After the engine starts turn the 10k resistor down to where I want it for better gas mileage.

Once a year we all have to take our car to the emission testing place before we can buy new license plates. About a week before the test remove the fixed resistor and plug in the air temperature sensor. Disconnect the car battery cables over night for about 10 hours next morning reconnect the battery cables. This will clear the computer memory. Drive your car about 100 miles so the computer will store some memory then take it to be tested.

I was going to attach some photos but decided to wait and see if anyone actually needs photos.

 

[tcmtech]

Neat trick!

I have been tweaking Ford emissions systems for some time now as well. It seems that regardless of auto manufacturer in the USA there is a load of fuel economy and power gains to be had if you can get away from the factory emissions system setups and limits.

Another interesting one is making an O2 sensor recalibration circuit so that you can bias the the A/F ratio richer or leaner than the theoretical stoichiometric setting the computer tries to maintain. Fords tend to do considerably better with a little richer setting opposed to the theoretical ideal or leaner levels.

The other change is to reroute the EGR line to feed fresh air from the air inlet system opposed to bad air coming from the exhaust system. In th old days you could just block the EGR valve off completely but the newer vehicles have a different sensor system that must sense actual air flow. Fortunately those sensors so far do not care whether its hot exhaust gasses or cool fresh air from the intake rather just that they see a volume of something going past an internal orifice and pressure drop sensor.

There are other tricks that can be done also like removing catalytic converters putting larger or freer flowing exhaust systems, taking out noise canceling baffling and restrictions in the intake (if used), and changing the camshafts and their respective timing to off road appication types but those changes are not as easily undone if a vehicle has to make it past an annual inspection.

 

[Reloadron]

Cool, a tips and tricks thread.

I got popped at my inspection last February. They would run the truck on a tread mill and analyze the exhaust. They never told me they changed that.

My truck is an 02 Yukon and it has a bad anti knock sensor in the rear under the intake manifold. Common problem for that year. The ***** is you need to pull the intake to get to the sensor. I tried everything to get the damn check engine light to go away. Disconnect battery, wait all night, tried it all and the fault would not clear. They will not test with that light lit.

So I went and got me a handy dandy trusty Actron Auto Scanner and cleared the fault. Fat dumb and happy I drive to the test center. Look mom, no light! Hell, unknown to me now they simply connect to the computer which clearly shows it had been reset.

So I told them I had jump started a friend with a totally dead battery when they mentioned that would cause it. They told me if I would sign a waiver (in case they crash my truck) they would use the old tail pipe emission test. Cool with me so on the tread mill it went and passed just fine. I am good for two years and got two year plates. Every few months it throws the fault and every few months I clear it simply because I get tired of looking at the damn light.

I'll have to try the temperature trick.

Ron

 

[gary350]

Last winter my vehicle had a sudden gas mileage drop to 9 mpg. I had noticed the heater was not getting very hot in the 20 deg F winter weather like it use to. Next I noticed the temperature guage on the dash was reading only 140 degrees F instead of 200 deg like it use to. I replaced the cooling system thermostate and the heater started getting hot again and gas mile returned to where it had been in the past. That made me decided to check the engine temperature sensor this is what tells the computer the actual temperature of the engine. It turned out the resistance was about 10% off so I replaced it and the gas mileage got a little better. Next thing I did was replace the old fuel filter and gas mileage got worse. The dirty fuel filter must have been a fuel restriction giving me better gas mileage. If I had not already thrown away the old fuel filter I would have put it back in. Now I am wondering if I can do something to make the new fuel filter dirty or maybe put is some type of fuel restrictor flat washer with a tiny orfice hole in it to restrict the fuel. Now I need to buy new oxygen sensors and test the resistance and compair that to the old oxgen sensors. New oxygen sensors are $65 to $150 depending on where you buy them. Maybe I can put a resistor in the circuit to make the old sensor resistance equal to the new sensor then return the new unused sensor for a refund.

 

[audioguru]

Fiddling with the pollution control devices on a car is illegal because it increases emissions (but makes the engine more powerful and smoother).
Frequently I get behind a kid in his old Honda car. The exhaust stinks due to the very high NOX emissions. When he "steps on it" then black smoke is in the exhaust like a diesel truck. The catalytic converter would burn up with such abuse so it must be removed then replaced just before an emissions test.

 

[tcmtech]

Next thing I did was replace the old fuel filter and gas mileage got worse. The dirty fuel filter must have been a fuel restriction giving me better gas mileage. If I had not already thrown away the old fuel filter I would have put it back in. Now I am wondering if I can do something to make the new fuel filter dirty or maybe put is some type of fuel restrictor flat washer with a tiny orfice hole in it to restrict the fuel.

More likely your vehicles lower fuel pressure caused the fuel injectors to spray a courser mist which burned in a way that tricked the O2 sensor control loop into running at a different fuel ratio which was better for power and fuel mileage. If your vehicle has a fuel pressure regulator you can get to you can modify it to run the delivery system at a lesser fuel pressure. Just restricting your fuel flow puts added strain on your electric fuel pump which is likely going to be on the expensive side to replace.

Now I need to buy new oxygen sensors and test the resistance and compair that to the old oxgen sensors. New oxygen sensors are $65 to $150 depending on where you buy them. Maybe I can put a resistor in the circuit to make the old sensor resistance equal to the new sensor then return the new unused sensor for a refund.

As far as O2 sensors go they are not resistance devices but voltage output devices that change their output as the computer changes the fuel delivery affecting the oxygen levels of the exhaust gasses that they read. Its a closed loop system that constantly cycles from slightly rich to slightly lean, about 2 - 5 times second, creating an average reading of what the computer trying to am for. Lastly they are temperature sensitive and do not work unless they are very hot.

A O2 sensor recalibrator circuit just amplifies that low, roughly .7 - 1.3 volts, signal to a higher voltage level where it can then be changed by a simple potentiometer to a value that runs slightly higher of lower than the actual sensors output is but still lets the up/down cycle of its reading continue.

Playing with the fuel delivery and O2 senor feedback loops is a lot more tricky than faking simple resistance based senor signals.

 

[audioguru]

The engine computer gives an error when it does not detect the rich-lean cycling of an O2 sensor (when it gets stuck or it is replaced by a resistor).

 

[shortbus=]

Fiddling with the pollution control devices on a car is illegal because it increases emissions (but makes the engine more powerful and smoother).

Here in the States we don't really care about the pollution any more. We found a cure for it. All the wind turbines are really big powered fans, and we blow the pollution towards Canada. Problem solved.

 

[audioguru]

Here in the States we don't really care about the pollution any more. We found a cure for it. All the wind turbines are really big powered fans, and we blow the pollution towards Canada. Problem solved.

I am glad that there are very few stinking smoking diesel cars here. Mostly trucks and busses.
I wonder what kind of oil school busses burn because their smoke stinks more than any other truck or bus.

 

[tcmtech]

I wonder what kind of oil school busses burn because their smoke stinks more than any other truck or bus.

They burn the same fuel as all other diesel vehicles get at the local fuel stations. Its the stupid government mandated diesel emissions systems and related detuning of the engines that need to inject urea into the exhaust system to keep the nearly pointless catalytic converter setup from sooting up since by nature diesel exhaust is not hot enough in most conditions to keep them burned clean.

Most larger diesel powered trucks are either just old enough to not have the urea systems or fall under a different emissions ruling that does not yet require them to run an urea injection system in their exhaust.

https://en.wikipedia.org/wiki/Urea

 

[Mr RB]

I heard it was a misconception that diesels pollute worse than gasoline, diesel engines make that very visible black smoke, but that is soot, ie large carbon solid particles. The diesel combustion process is more complete and efficient, and the exhaust is cooler and contains more inert solids (like the soot you can see). The soot falls to the ground.

Gasoline engines have a higher temperature exhaust with more nasty gaseous emissions that diffuse into the atmosphere (local air pollution) or work their way up high in the atmosphere to cause greenhouse effects.

So that "dirty smoking diesel car" is better for you than the cars around that you don't see their exhaust...

 

[Birdman Adam]

Plus the modern diesels I see are VERY clean burning. Like there isn't a single hint that it is diesel.

 

[ghostman11]

i found a much easier way to double my fuel savings and i dont have to mess with the engine!! now days i goto town twice a week instead of fours times simples

 

[gary350]

i found a much easier way to double my fuel savings and i dont have to mess with the engine!! now days i goto town twice a week instead of fours times simples

I learned to turn the motor off at all the RED traffic lights. I use to burn 3/4 of a tank or gas every week so I had to fill up every weekend to be ready for the next work week. Now I burn less than 1/2 a tank per week so now I only fill up every 2 weeks. I have been doing this for 7 years. I have had several people tell me that will over work the starter and you will be replacing the starter and the flywheel but 7 years later no problems. I traded vehicles now I do it with the new vehicle. I do not restart the engine until the 3rd car in front of me starts to move. People are slow to take off it typically takes 1 to 2 seconds for each pers to go. I can restart the engine in 3 seconds have it in drive and off I go.

 

[Nigel Goodwin]

I learned to turn the motor off at all the RED traffic lights. I use to burn 3/4 of a tank or gas every week so I had to fill up every weekend to be ready for the next work week. Now I burn less than 1/2 a tank per week so now I only fill up every 2 weeks. I have been doing this for 7 years. I have had several people tell me that will over work the starter and you will be replacing the starter and the flywheel but 7 years later no problems. I traded vehicles now I do it with the new vehicle. I do not restart the engine until the 3rd car in front of me starts to move. People are slow to take off it typically takes 1 to 2 seconds for each pers to go. I can restart the engine in 3 seconds have it in drive and off I go.

A lot of modern cars do this automatically, with the engine restarting as you depress the throttle.

 

[3v0]

Some of the mods listed here lean out the car to where it will die if you put you foot into the throttle. Wonder how much of the savings is due to the mod vs not stepping on it.

Regarding the fixed resistor to defeat cold enrichment. I would think a resistor in parallel or series with the sensor would be a better idea. That way you would get some compensation for temperature. Or you could get wild and put in a micro controller that read the existing temp sensor and map it to your own curve.

 

[tylernt]

I'm no electrical engineer but I do know a thing or two about cars: leaning the air/fuel mixture excessively causes a dramatic increase in combustion chamber temperatures. At best this will make your car prone to overheating, and your spark plugs won't last as long due to oxidation. At worst, you can melt spark plugs or exhaust valves or even melt a hole right through the top of a piston.

The latest lean-burn direct-injection engines have to have some very carefully engineered combustion chamber geometry to allow a buffer of cool air to prevent the lean flame front from melting engine internals like a (literal) blowtorch. If you don't have a direct-injection engine, you are risking engine damage when you lean it out. How much risk depends on how much you lean it and the shape of the combustion chamber.

 

[audioguru]

A lean mixture also causes increased nitrous oxide pollution, doesn't it?

 

[tylernt]

A lean mixture also causes increased nitrous oxide pollution, doesn't it?

Indeed it does: https://en.wikipedia.org/wiki/NOx "They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures."

 

[audioguru]

OOps. It says NOx on my car's emissions test certificate, not Nitrous Oxide. They are very different.

My car produces almost no NOx because its pollution controls are not modified and work properly.
Unlike in Europe, the gasoline in my part of Canada is not overly taxed so it is still fairly inexpensive ($1.23CAN per liter today). So I "step on it" whenever I feel like it.