I was thinking of something. I know porting the stock maf throws the cars computer calibration all off and makes the thing run all sorts of rich and lean, i was wondering if people were seeing this also when they threw on their NX MAF ends? Anyone see a diffrence in your A/F ratio from when you used your stock MAF to using the maf ends from NX and your stock middle sensor? Lemme know, post away all your NX maf end users.

 

ttt anyone?

 

Interested to know also?
Would you have to re tune the computer for the bigger MAF ends becuase I am pretty sure that you have to retune for ported ends?

Joseph

 

We have seen a small hp increase with the MAF ends on LS1 cars. But we did not have to retune. Also I am not sure what it did to the tune up Could not have been much since we did not retune anything. Sorry not much help.
Ricky

 

I have never heard porting the MAF ends causing any type of lean condition. It will still read all of the air comming in--since all of the air will fit through the MAF and be going through the sensor. The sensor will read the increase in flow and adjust the fuel as neccesary.....that is the whole point of the MAF sensor....changing the ends does nothing to the sensor it's self....that would be like saying changing the intake will cause a lean condition. NX MAF ends will not cause you to go lean.

 

Actually, the sensor only measures the small portion of air that removes the heat from the wires, allowing the MAF to compute the heat loss, and thereby the mass flow rate. But to do that calculation, it has to assume that the velocity of the air passing the wires is similar to the velocity in the entire face area of the meter, or it has to know what the distribution of flow velocity accross the face of the meter is.

It is this possible variation in flow velocity that is the basis for the calibration table loaded into the PCM. If you change any aspect of the meter's physical makeup - remove the screen, open up the "ends", remove the divider, change the inlet ducting in front of the sensor, etc - you alter the calibration of the meter.

The meter calibration will not be particularly sensitive to the changes made downstream of the sensor, and I'm assuming that the NX "ends" spray the cold fuel/nitrous mixture downstream of the sensor. The only possible impact woud be any heat that the expanding nitrous might pull out of the sensing element, as it cools down the body of the sensor. But, once you change the geometry of the "ends" you have altered the air flow distribution accross the face of the meter.

 

So you are saying it will make you go lean? If so then i have to disagree.


The velocity of the air will HARDLY change with these ends. The sensor it's self is a certian width in diameter and then the ends go on to the sensor....all the air is forced through the sensor witch the cross-sectional area of the sensor is never changed. And Flowrate= Area x Velocity. So the air sensor reads the velocity as you mentioned and the sensor has a certian width that is never changed, therefore nothing has changed. If the MAF ends are changed (you might) see and increase in Velocity, but the sensor will read this by as you stated....calculating how much extra heat is loss. Also as stated by Injuneer the MAF assumes the air in the center is flowing at the same velocity as the air near the out side, which is not 100% accurate due to friction and turbulence. So the meter has error in it's self and it is calibrated to adjust to this. It's not as accurate as they make it seem to be, measing your O2 sensors is a better way to read A/F ratio.....that is why they use a wideband O2 for tuning. Because even knowing the incomming air by the MAF doesn't tell you exactly what clinder gets what percent of that air.

You will not be lean using those ends N/A, or when you spray, since it is sprayed after the sensor. You will be fine.

 

No... you didn't read carefully. I said altering any physical aspect of the meter will alter the calibration. Might cause the sensor to incorrectly measure the air flow either high or low.

As you yourself noted above, the velocity distribution across the open area of the meter is not unifom.... disrupt the velocity and you alter the calibaration, plain and simple. And again, I didn't say it would cause it to run lean.... perhaps you could point out where I said that.

 

I did read carefully. He is asking if he uses the MAF ends if it will cause a lean condition.....that is what he wants to know. Do you consider using the NX MAF ends (not the meter) changing the physical aspect of the meter?? I am answering his question, and you are telling him how a MAF sensor works.....


And it is still un-uniform when you put different ends on it so nothing changes. The center and outer velocitys will have a correlation. If the center velocity changes the outer one will too correct? The sensor will read this center velocity and account for the air....the outer velocity will have the same ratio to the inner velocity as the original velocities. <<<a little confusing.



I was not reffering to anything you said, that it would go lean, i was asking, because that is what he wants to know. Your whole post was telling me how a MAF sensor works. So what do you think, will it go lean? I was giving him my opinion, then you quoted me and told me how I was wrong.