169 | Is Your Mass Airflow Sensor Big Enough?

Hi Andre

it has been a while since im trying to re scale the maf for better performance.

I tested 2 diff diameter of maf housing ( 2.3'' & 3" )

at both im getting the same highest maf g/s with diff reading of mafv ( 2.3" max mafv 2.15 / 3" max mafv 4.02 above these voltage the maf g/s max out)

i also tested long intake and short intake and diff maf sensors. I can see the diff btw them at idle and cruise but at wot im getting the same max maf g/s

im stuck at it and i don't know why. I also tried bigger injectors and still having same result. My stock injector around 93%.

I have few questions:

* Does low fuel pressure or weak pump can limit the maf reading ?

* Does high VE can cause a limit of maf reading ?

i did some online calculation and i found out that im at around 97% VE

* What else can limit the maf g/s ?

Looking forward for your reply

What is the specific engine you're tuning? Some ECUs do have a hard coded limit for the MAF output that you can't change although this is rare. This sounds like it could be the issue your striking. Are you finding that regardless of the MAF housing you're using that you get to a mass airflow value you can't exceed?

I'm not sure I follow your results though - Are you saying that with the 2.3" MAF housing the MAF maxes out at 2.15 volts but with the 3" housing it maxes out at 4.02v? If so that seems backwards to me. You should achieve the same flow at a lower MAF voltage from the larger 3" housing.

It’s 4cyl bolth on + Camshaft ( NA )

Using biggyback ecu -

Sorry i meant with 2.3” maf housing

after rescalling the maf i reach 4.15v

and im getting the same maf flow with 3” maf housing at around 4.02+

At both housing im getting the same max flow which is around 110 g/s and more than that it will give me wrong reading around 750g/s

the flow doesn’t want to go above 110g/s

My guess is that you're not going to be able to get a proper result on this combination with a piggyback ECU. I'd say the only way you're going to be able to deal with this is via a reflash package for the stock ECU or you could fit a standalone ECU. This is a problem with piggy back ECUs in some instances where you need to have more control than the piggy back ECU can provide.

I'm not quite sure what your point is - is it that you have fitted a larger bore MAF (Mass Air Flow) sensor body and haven't realised the overall increase in airflow you expected?

If so, it is most likely due to the original one not being a significant restriction in the overall intake system. Like replacing a short section of exhaust pipe with a larger bore but leaving the rest of the exhaust the same size - there may be a very small imporovement but the rest of the system is still causing a restriction.

Same thing with larger throttle bodies, camshafts, etc - it they are already up to the job a 'better' one may not be much of an improvement if the problem(s) lie(s) elsewhere.

@Gord - The way I'm reading the situation is that in stock form Ahmed was exceeding the flow limit of the stock MAF so he's moved to a larger housing but is not tapping a hard coded mass airflow limit.

Thank you Andre @Gord

yes Andre your u got my point but actually the stock form is 2” and i used the 2.3” aftermarket maf housing connected to 3” pipe with V-Stack in the end and then i moved to 3” housing with 3” pipe with v-Stack

coz I thought i might get more air flow but as i said before it doesn’t want to go above 110 g/s

each time it goes above that number i get an error

that’s why i was wondering what the cause of that ?

Without being able to say with absolute certainty, this is likely to be either the maximum value in the MAF scaling table inside the stock ECU, or potentially a hard coded limit. Either way you won't be able to fix this with a piggy back ECU.

Thank you so much Andre for your reply

I guess the piggyback my mine issue.

what about fuel filter & fuel pump or low pressure fuel .does one of them can cause that as well ? as i knew the fuel pump sometimes it limits the hp of car .

Thank you

Ah, I stand corrected :-)

It's possible that you may need to rethink your fuel system if you've got a significant increase in engine power. I'd be looking at your fuel pressure and injector duty cycle to decide if your fuel system is big enough. It's unlikely from what you've described though that this is your main problem.

Thank you Andre for your reply..

Injector duty cycle around 85 - 90%

but im not sure about the fuel pressure.

I'll try to check the fuel pressure.