Air intake heat sensor: AU XR8

[Lukeyson]

hey all

i got told the other day that if i get a 'ceramic capacitor' and use it to short out the temp sensor on the rubber intake pipe on my XR8 it will trick the motor into thinking that the air it is sucking in is really cold.
I am pretty sure i remember reading about that on here ages ago, but couldnt find the thread.

Question is, is that info accurate ?
if it really did work, what advantage would it give? the ecu thinking the air is 10degrees when its really 40degrees outside ?

[StealthAu]

Results in your car running lean, possibly resulting in the need for a new bottom end.

[RG]

Originally Posted by StealthAu

Results in your car running lean, possibly resulting in the need for a new bottom end.

If it thinks it is cold air I think it would richen the mixture so all you'd do is use more fuel and foul up your plugs.

[Lukeyson]

thats it, i thought it should know the real temp , otherwise they wouldnt have put it there !
thanks for clearing it up

[StealthAu]

Originally Posted by Russell

If it thinks it is cold air I think it would richen the mixture so all you'd do is use more fuel and foul up your plugs.

Codler air is dencer air. Basically colder air has more oxygen, more oxygen means less fuel required for same result. Tell the computer air is cool on a hot day results in the car running lean.

[madmelon]

Originally Posted by StealthAu

Codler air is dencer air. Basically colder air has more oxygen, more oxygen means less fuel required for same result. Tell the computer air is cool on a hot day results in the car running lean.

...colder air has more oxygen per unit volume and therefore requires MORE fuel to maintain a stoic. mixture. If the car thinks the air is colder, it will run richer.
More oxygen = can burn more fuel = more power

[StealthAu]

To put it in real simple terms, if you do much highway driving you'd notice you get slightly better economy on long trips taken place on cool nights rather then 40 degree days. If you can't work it out on this info too bad as I'm not wasting anymore time trying to convince anyone of the basics.

[AUXRVIII]

Originally Posted by XR8fella

hey all

i got told the other day that if i get a 'ceramic capacitor' and use it to short out the temp sensor on the rubber intake pipe on my XR8 it will trick the motor into thinking that the air it is sucking in is really cold.
I am pretty sure i remember reading about that on here ages ago, but couldnt find the thread.

Question is, is that info accurate ?
if it really did work, what advantage would it give? the ecu thinking the air is 10degrees when its really 40degrees outside ?

It may run mildly richer but the oxy sensor, engine coolant temp sensor, airflow meter and throttle position sensor feedback may be enough for the PCM to adapt and after a short time there will be no difference.

[RG]

Originally Posted by StealthAu

To put it in real simple terms, if you do much highway driving you'd notice you get slightly better economy on long trips taken place on cool nights rather then 40 degree days. If you can't work it out on this info too bad as I'm not wasting anymore time trying to convince anyone of the basics.

Geez wtf is your problem mate?

Colder air will make it run richer as the air is denser hence the reason cars run better in cold air.

[5.0 ED]

well a ceramic capacitor has no resistance value to it, it opposes change, it will in fact do nothing at all to you car, except change the time it takes for your temp sensor signal to change to its new signal, and being that you have said a ceramic which are of low capacitance values will delay/smooth temp change seen by the computer by a couple milliseconds depending on the value you purchase.

Basically a total waste of time that will achieve nothing for you.

you can put a resistor across it and change its value, but the results of which arnt ideal as it makes your car run richer, decreases ignition timing, and theoretically should lose power and fuel economy.

[5.0 ED]

oh and colder air is yes more denser and require more fuel to run at correct air fuel ratio's, the temp sensor is there to give the engine more fuel when cold air is present and less when intake air is hotter. Being that majority of fords are tuned to rich from factory, then if you think about it, you'll realise that you would want the sensor to infact read hotter than it actually is. so that the car will run leaner to get closer to full power air fuel ratio's.

[StealthAu]

Originally Posted by Russell

Geez wtf is your problem mate?

Colder air will make it run richer as the air is denser hence the reason cars run better in cold air.

You are right, well kind of. A car will run richer at night but in newer cars like the AU, the ECU detects colder air temps and trims the fuel. Hence better economy in cooler temps.

Had a look on youtube but this is the best I could find to try and help explain what I am saying.
http://www.youtube.com/watch?v=HnFyie-K_Co
So as you see, same fuel, more oxygen results in more energy producced.

[RG]

Originally Posted by StealthAu

You are right, well kind of. A car will run richer at night but in newer cars like the AU, the ECU detects colder air temps and trims the fuel. Hence better economy in cooler temps.

Had a look on youtube but this is the best I could find to try and help explain what I am saying.
http://www.youtube.com/watch?v=HnFyie-K_Co
So as you see, same fuel, more oxygen results in more energy producced.

Newer cars maybe but not the old Windsor.

[StealthAu]

Originally Posted by Russell

Newer cars maybe but not the old Windsor.

In the AU yes, in carb fed windsors, no. As I have already said this is why you would get better economy on a cold night then a hot day.
Maybe everyone who has posted in this thread should do a search on ebay for these intake mod, because it even says in their discriptions that it tells the ECU colder air is comming in resulting in a leaner mix.

Also contact any tuner and ask if making a stock AU XR8's mix richer would increase power.

[AUXRVIII]

Colder air brings more power, not better fuel economy. The better economy which may result is due to more power being produced so less throttle percentage is required to get the same performance, the throttle position sensor is used along with others to calculate req fuel, especially in the AU V8.
Modern EFI systems are able to adapt, when the air is denser, more fuel will be injected to maintain correct airfuel ratio otherwise a lean signal will be produced by the oxy sensor. Leaner running also brings higher nox emissions which by gov regs is not permitted.

[AUXRVIII]

http://www.freeengineinfo.com/air-temp-sensor.htm

[EvilChief]

now above you see a standarised air temp correction map (ignore the actual correction values as such). almost every correction map aftermarket or standard looks similar to this.

as air temp increases fuel is removed to adjust AFRs for the less dense air. Denser (colder) air requires more fuel.

Best example is the cold post start enrichment map, as the name suggests, for a period of time, post start up while cold and extra percentage of fuel is added to compensate for the lack of fuel atomisation and cold operation of the engine.

Resistance increases as temperature increases, hence a higher resistance resitor is used to replace the air temp sensor.

this theory as all nice and good, BUT EECV are a self learning and adjusting ECU, which can adapt for sensor malfunction as well. Other correction values, such as Cool correction, O2 correction, baromtric correction, etc will over time compensate for the misleading Air temp sensor readings and adjust for it (getting AFRs readings as close to the AFR target values preset at factory or tuner as possible)

colder air is more dense, meaning a higher percentage of O2 is present in X amount of volume of air, compared to hotter air.

ie:
cold air has 50 O2 molcules in X litres of air you will require 3.4 molecules to achieve a 14.7:1 AFR ratio
if not hotter air has only 40 molecules in X litres of air you will require 2.7 molecules to achieve a 14.7:1 AFR ratio.

now in this theory hotter air is more fuel economical, but produces less power as you get less bang (less O2 + less fuel = less bang)