Owain1602 0 Posted March 14, 2007 Why does a car with an Air mass meter, not an air flow meter, need an inlet air temp sensor(usually part of the air mass meter)? Anyone know. Share this post Link to post Share on other sites
welshpug 1,657 Posted March 14, 2007 because it needs to differenciate between more air coming in and colder air (air Mass meters are another name for hot wire sensors IIRC) but then air flow meters (like the 205 has) have temperature sensors too! Share this post Link to post Share on other sites
acox99 74 1 Cars Posted March 14, 2007 It is part of the hot wire circuit, it makes up part of the Wheatstone bridge i believe making the reading more accurate and giving faster reponse times to temp changes and flow rates. Share this post Link to post Share on other sites
PumaRacing 2 Posted March 15, 2007 Why does a car with an Air mass meter, not an air flow meter, need an inlet air temp sensor(usually part of the air mass meter)? Anyone know. Because it isn't really measuring air mass. It's measuring how much the airflow cools down a heated platinum wire, in fact how much current it takes to maintain a given resistance in the wire. However the cooling effect of more warm air and less colder air could be the same and it can't tell the difference unless it also knows the air temp. Share this post Link to post Share on other sites
Owain1602 0 Posted March 15, 2007 I would say puma racing's answer is the best Share this post Link to post Share on other sites
ini 0 Posted March 15, 2007 It is measuring the air density, not just the flow rate. Share this post Link to post Share on other sites
Owain1602 0 Posted March 16, 2007 Thats what the element is for, instead of the normal flap. It doesnt need the air temp sensor to measure density that is the benefit of the HFM. I know how they work inside out thanks, I just knew if i was to ask the particular question then someone was bound to say what you have said above. Share this post Link to post Share on other sites
bales 1 Posted March 17, 2007 (edited) Cos 1kg of warm air could have the same cooling properties as 750g of cooler air. (edited to add: oops just noticed pumaracing has already said that) Edited March 17, 2007 by bales Share this post Link to post Share on other sites
