Care to explain how air/fuel is altered when all of the airflow that enters the engine is drawn through the MAF(Mass Airflow Meter)?twogts4us said:In theory, anything more free flowing than stock will cause a lean condition, not rich.
Sure Johnny - Less backpressure, which causes more air to be drawn into each cylinder. Though a set amount of air may flow through the MAF, whether or not it makes it into the cylinders is affected by the amount of backpressure through the exhaust system.JohnnyLangton said:Care to explain how air/fuel is altered when all of the airflow that enters the engine is drawn through the MAF(Mass Airflow Meter)?
JL
So the engine is magically producing air?twogts4us said:Sure Johnny - Less backpressure, which causes more air to be drawn into each cylinder. Though a set amount of air may flow through the MAF, whether or not it makes it into the cylinders is affected by the amount of backpressure through the exhaust system.
engines don't produce air they pump air. A free flowing exhaust will scavenge exhaust out of the ports more efficiently. Creating this 'extra room' in the exhaust port while the engine is running means that the otherwise unchanged engine will flow more air. Forutnately the EEC is capable of compensating for this and will add the needed fuel to keep the A/F in check.JohnnyLangton said:So the engine is magically producing air?
JL
Well,No ****...jstreet0204 said:engines don't produce air they pump air. A free flowing exhaust will scavenge exhaust out of the ports more efficiently. Creating this 'extra room' in the exhaust port while the engine is running means that the otherwise unchanged engine will flow more air. Forutnately the EEC is capable of compensating for this and will add the needed fuel to keep the A/F in check.
JohnnyLangton said:Well,No ****...
The more free-flowing exhaust will scavenge a bit more air,and that air has to come from somewhere...the air inlet tube..and what's connected to that tube?
That's right,the MAF.
Therefore stating that headers,etc will make a car run leaner is simply BS,and is the typical answer of somebody that knows nothing about the engine management system on an EEC controlled Ford.
JL
Where did you come up with this?JohnnyLangton said:So the engine is magically producing air?
So are you are saying that regardless of the exhaust mods, every bit of air metered makes it to the cylinders, and the EEC will automatically compensate and adjust the A/F? Please share with us your wealth of knowledge on the EEC. Nonetheless, technical info and a healthy debate are welcome, but no need for your attitude.JohnnyLangton said:Well,No ****...
The more free-flowing exhaust will scavenge a bit more air,and that air has to come from somewhere...the air inlet tube..and what's connected to that tube?
That's right,the MAF.
Therefore stating that headers,etc will make a car run leaner is simply BS,and is the typical answer of somebody that knows nothing about the engine management system on an EEC controlled Ford.
JL
Saleen201 said:What he is saying, is that all the air entering the engine must go though the MAF. The MAF tells the computer how much air is going into the engine, and therefore, can determine how much fuel to add. Yes you will have a less restrictive exhaust allowing air to flow easier, meaning the more air can enter/exit the car. The computer will also compinsate for this (because, remember, all air going into the engine goes though the MAF) by adding more fuel.... keeping your air/fuel mixture the same.
If you dont have cats, it shouldnt have an effect on your air/fuel mixture, just emissions. LTs will effect it because it puts the O2 sensors further away from the exhaust ports, allowing the air to cool causing a slight missreading. or so i have heard, i hope somebody else can clarify this.
GT2000JAY said:I don't believe your a/f readings will change that much as a result of moving the O2's. Otherwise widebands that use a sniffer in the tailpipes would be completely ineffective (with a catted midpipe they will read off - usually lean).
However, moving the O2's further down stream will change the delay between the O2 sending it's reading to the PCM and the computer making small adjustments to the mix - this delay can be corrected/adjusted with a tune.
A/F will be close to 14.64:1 at idle/part throttle (closed loop) and will be what is commanded at WOT (open loop). There is really no way around this.
Closed loop is when the EEC depends on sensors to adjust timing fuel etc. Open loop depends on defined tables, and slightly on some adaptive variables defined during closed loop operation. Open loop occurs during warm up and WOT.Saleen201 said:Closed loop is when your car is still not at operating temperature, your computer keeps emissions functions cut off untill the car warms up. Open loop is after the car has reach operating temperature and emissions fuctions resume.
I didnt know closed loop was at idle and open loop was WOTI could be wrong.
-Mike
GT2000JAY said:I don't believe your a/f readings will change that much as a result of moving the O2's. Otherwise widebands that use a sniffer in the tailpipes would be completely ineffective (with a catted midpipe they will read off - usually lean). However, moving the O2's further down stream will change the delay between the O2 sending it's reading to the PCM and the computer making small adjustments to the mix - this delay can be corrected/adjusted with a tune.
jstreet0204 said:This is true on self heated o2's like ours, but putting a wideband further down stream in the tailpipe does read slightly leaner. I can tell a slight difference with my PLX by putting it in the front bung and the back bung, (I don't have any cats) but there is a greater difference by putting it in the tailpipe. I beleive this has more to do with initial exposure the outside air though.
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