[boogle2]

Hey Guys,

As I am contemplating supercharging my car, I was wondering, is there any drawbacks to running a MAFless tune? Is the motor now less adaptable to changing atmospheric conditions or vehicle performance? Curious as to your thoughts.

Thanks,
Rob

 

[rao]

The short answer is no if the tune is done correctly.

When the S62 is set up not to use the MAFs it runs what people call "alpha-N" which uses air temperature, throttle position and engine RPM to calculate the amount of air entering the engine. If done properly it can work quite well. The MAF is a more direct measurement of air entering the engine but most systems (including the S62) do not use it in all conditions (such as at WOT) because the MAF is fairly slow to respond so it is better suited to steady state conditions.

This issue has been discussed here and elsewhere endlessly so there is a lot to read, some of it even good hiha.

 

[FL_M5]

Why go MAFless?

 

[boogle2]

My assumption was that the tunes that ship with most S/C kits don't use 'em. Am I totally out to lunch?


Sent from AutoGuide.com Free App

 

[Flyin-m5]

MAF's can and do go bad.

Thats the reason to eliminate them.

:M5rev:

 

[FL_M5]

I didn't realize that the FI kits were MAFless. I guess it easier to eliminate the MAF's to simplify the plumbing... Oh well

 

[Bimmerbear]

.....but most systems (including the S62) do not use it in all conditions (such as at WOT) because the MAF is fairly slow to respond so it is better suited to steady state conditions.

I have an incredibly hard time believing that. What's your source for that info?

MAF's can and do go bad.

Thats the reason to eliminate them.

:M5rev:

How about don't be cheap and replace them?

With as anal and optimization-obsessed everyone on here is about these cars, I'm shocked that alpha-N has gotten to be as big as it has.

 

[Flyin-m5]

I have an incredibly hard time believing that. What's your source for that info?


How about don't be cheap and replace them?

Buy an Evolve tune,solve drivability,SAP codes and get a steering update of your choice for almost what a set of MAF's cost.



PS-I have some used MAF's if you want to buy them

 

[Bimmerbear]

Buy an Evolve tune,solve drivability,SAP codes and get a steering update of your choice for almost what a set of MAF's cost.



PS-I have some used MAF's if you want to buy them

Sounds like you can't afford to drive this vehicle then.

Solve drivability? What does that even mean?

 

[Flyin-m5]

"Sounds like you can't afford to drive this vehicle then".

Thats why I have 2.

So......you want to buy my MAF's because you're not cheap?

Is that what I'm hearing?

:M5thumbs:

 

[griffincox]

I have an incredibly hard time believing that. What's your source for that info?

Which part? MAFs are best used to measure air during steady state. They are inherently very bad at measuring air entering the combustion chamber during transient throttle/manifold pressure situations. This is the reason that they rarely measure airmass by themselves and rather are "backed up" by either SD or Alpha-N. As far as which is used, when, and in what proportion in the S62 DME, no clue, but it makes more sense to use the MAF at WOT (100& throttle, no change in angle) because its would be more steady state than rapid throttle changes (like the ones that happen at 600-3500+ rpm during rapid pedal/throttle changes, shifts, etc).

 

[bfp9]

Sounds like you can't afford to drive this vehicle then.

Solve drivability? What does that even mean?

Solid reasoning - I see no fallacies here.

 

[hillco148]

Mr Bear.. Go back to your hole start a early hibernation.

 

[rao]

I have an incredibly hard time believing that. What's your source for that info?

I made it up :dunno:

How about don't be cheap and replace them?

With as anal and optimization-obsessed everyone on here is about these cars, I'm shocked that alpha-N has gotten to be as big as it has.

No kidding. It is unseemly to see this sort of behaviour by owners of a supercar :hiha

 

[Enrico 2000]

So what's the verdict on the OP's question ? Without getting too side tracked. If SC then u have no choice but to go mafless ( I presume ) because of the custom tune. But why go mafless or alpha-n in the first place ?

 

[rao]

So what's the verdict on the OP's question ? Without getting too side tracked. If SC then u have no choice but to go mafless ( I presume ) because of the custom tune. But why go mafless or alpha-n in the first place ?

Once again I am making this up, but I am pretty sure that I answered the OP's question.

You could continue to use MAFs with forced induction.

From what I have read the only reason to go MAFless is because you are too cheap to pay for new MAF sensors.

 

[SleeperE39]

Count me in as one of the too cheap crowd as I run Evolve's Alpha-N sans MAF - Stock Motor.

Daily Driver - over 120K km's so far without MAF's
Winter @ < -20C
Summer @ > +38C

Idles fine, closed loop response good, WOT response good.
Sport mode sticky, no emissions issues, no SAP
Oh - and no MAFS to replace when your but dyno is thinking something is wrong with the car.

Pre Alpha-N - how much money was being spent on un-necessary MAF replacements because the collective "wisdom" of the community has concluded that the MAF's appear to be the #1 suspect in achieving the holy grail of 140L/hr fuel flow.

I have a whole stack of invoices for all of the other necessary replacement items to keep a 13 year old daily driver in somewhat decent shape.

So I guess the only drawbacks of going MAFless is my parts dude doesn't get my money.

 

[silverbullitt]

Hey Guys,

As I am contemplating supercharging my car, I was wondering, is there any drawbacks to running a MAFless tune? Is the motor now less adaptable to changing atmospheric conditions or vehicle performance? Curious as to your thoughts.

Thanks,
Rob

I enjoy how no one has really answered this for you... not. This thread got derailed faster than most of the ones on the Nebraska Rivals site do, and that's saying something.

As another poster pointed out, the MAF is a way to measure the air going into the engine. Without a MAF, there is no way to actually measure that. What you CAN do without a MAF is estimate that value VERY closely using various other sensors and correlating with oxygen sensor readings.

So, without MAFs, you're subject to the tune's estimation method. Where this can go wrong is if your conditions differ from those that were used to create that tune. Generic tunes using a MAF usually (ok, I'm making this up but it makes too much sense to not be probably true) have a better/more adaptable method to adjust for your car's ability to take in air. By fine tuning a base calibration of an alpha-n tune, you can get it to run better than any MAF using tune, simply due to its ability to respond MUCH faster and not experience the restriction of the MAF in the airflow.

 

[Kelster]

Hey Guys,

As I am contemplating supercharging my car, I was wondering, is there any drawbacks to running a MAFless tune? Is the motor now less adaptable to changing atmospheric conditions or vehicle performance? Curious as to your thoughts.

Thanks,
Rob

One of the first successful supercharged E39 M5s was the Dinan S3. It did not use MAFs.

--Ray

 

[rao]

I enjoy how no one has really answered this for you... not. This thread got derailed faster than most of the ones on the Nebraska Rivals site do, and that's saying something.

As another poster pointed out, the MAF is a way to measure the air going into the engine. Without a MAF, there is no way to actually measure that. What you CAN do without a MAF is estimate that value VERY closely using various other sensors and correlating with oxygen sensor readings.

So, without MAFs, you're subject to the tune's estimation method. Where this can go wrong is if your conditions differ from those that were used to create that tune. Generic tunes using a MAF usually (ok, I'm making this up but it makes too much sense to not be probably true) have a better/more adaptable method to adjust for your car's ability to take in air. By fine tuning a base calibration of an alpha-n tune, you can get it to run better than any MAF using tune, simply due to its ability to respond MUCH faster and not experience the restriction of the MAF in the airflow.

The first reply answered the OP's questions.

One of the first successful supercharged E39 M5s was the Dinan S3. It did not use MAFs.

--Ray

Everybody knows Dinan = cheap. I wonder if they realized that this is a supercar?