Mass Air Flow Sensor

[drivetrainUW-Platt]

I was wondering in any teams have run a MAF sensor on there car, why or why not?

[drivetrainUW-Platt]

I was wondering in any teams have run a MAF sensor on there car, why or why not?

[Colin]

The MAF sensors i've seen (OEM stuff) are very fragile so i'm not sure how long they would last in this type of application they also have to be mounted in the middle of the air flow which is going to create some disturbance in your intake flow

[Alexandre D.]

We used a MAF for some time. I don't know why you think they are fragile... Don't smash them with a hammer and they'll be fine.
They are useful if you're planning to do extensive dyno testing. If you spend minimum time at the dyno, it won't be useful.
I'm not scared about the flow disturbance. Just place it far away from de restrictor. Of course most of the MAF are designed for oversized intake(for FSAE). A calibration may be needed for a smaller more adapted intake. Be sure to have everything to run a flow bench.
It'll cost you a lot of time and money(It is quite expensive). But if you do extensive dyno testing, a MAF will be a useful tool.

[Charlie]

There seems to be two different arguements here. One is to have a MAF on the car. Another is to use the MAF to test. I don't see a reason to run a MAF on a car. I do think it cna be a useful testing tool.

MAF sensors seem like ideal sensors because if you know air mass, and know fuel mass, no tuning is required! Just chose your target lambda and go!

However it is not that simple. MAF sensors are not very accurate 'out of the box' and must be specifically calibrated to the specific application. This is because they require steady laminar flow at a constant cross section (because the reading is only a small sample). Also, reversion means double counting on a hot wire MAF. Some hot wire MAFs have an anti-reversion so they don't count outward flow. But they still count air that goes in that eventually comes out so it only fixes half the problem.

The result is that OEMs calibrate thier MAF sensors on the complete intake system, with another MAF far ahead of the system with a giant resevoir in-between. Basically run the engine at steady state until you get a good damped reading way ahead of the engine and calibrate it that way.

You can do this is you want. But you are only doing it for the ability to put a heavier and bulkier sensor on your car, and one that is sensitive to dirt and oil.

On the other hand, I think a MAF sensor, positioned the best you can as far as damping, is a great tool on the dyno. When you can't remap to see power increases, at least you can see airflow increases. And a MAF off a small low RPM 4 cyl will give you a decent range sensor and is cheap in the junkyard or ebay.

We used a MAF sensor with the factory calibration to test with, it was obviously not the right numbers but for comparisons it was invaluble. That along with a lambda sensor to verify it's correct operation (if it shows more air, does the lambda show lean?) and keeping in mind that large unusual spikes not lambda verifyed were probably reversion, we got good testing done. We found power the dyno didn't show because it wasn't properly mapped for it yet.

[drivetrainUW-Platt]

Charlie,
I do realize that the MAF sensor just be calibrated for our application, but once that is done wouldn't be a better choice overall for air density readings? Also, in all my EFI research I have never seen lambda explained, anyone care to give me a description of what is meant by that term?
thanks

[Charlie]

Once it's calibrated would it be a better overall choice? No I don't think so. Not when for the work it takes to calibrate a MAF sensor would give you a MAP or TPS based system totally mapped that is lighter and (arguably) more reliable. Just my opinion.

If you can't find what lambda means in your research you aren't trying very hard; It's just a ratio of ratios. Actual A/F over Stoich A/F.

[John Bucknell]

I'm with Charlie - MAF sensors are a lot of work to get functional. MAP in a single throttle application like FSAE is far simpler - and density is nearly as good as mass flow for fuelling calculations.

[avillarc]

Does anyone know about a MAF Sensor that works well on a F-SAE car that brings a Voltage Vs. Air Flow Charts?

[formula_wally]

MAF sensors are best used with a more integrated control scheme, ie an OEM control unit. It is meant for the street as it used to create fuel pulses more numerically, than physically, in hopes of showing efficiency and environmental care.
Typically your flow from Closed to Wide Open Throttle will change based on RPM. This is not a big deal yet you will need an augmented control on your look-up table for your load/rev map. This plays to an anti-linear response and loss of detail in the calibration.

MAP (or speed density) is a step closer to a racing solution. It suffers from loss of detail and part throttle tuning accuracy near the upper end of the load. It does work well though, if there is sufficient plenum volume, and good vacuum seal.

TPS, of Alpha-N has been commented as the best racing solution for load sensing, as it create much detail in 50% TPS open to WOT. Most race cars should operate near WOT, and our series is close to it, yet tight corners and hard cornering does drive the load down, such that there is still a need for low end resolution in the load site.

I think the most important goal of determining the load is to find the best solution which gives the driver the most linear feel with their controls, so they can make the car do what it needs to be doing.


A little cover fire
http://www.carcraft.com/techarticles/electronic_fuel_injection/

[Poe]

http://www.guzzimental.com/documents/alfa/Bosch%20HFM5%20Sensors.pdf

We use one of these, just pick the size you deem appropriate.