What does a maxed AFM feel like?

[maximajim]

I'm thinking I'm fully maxing my AFM but I can't really tell. It struggles to reach 15psi and pops past 5500 rpms. Should I replace the maf or is it something else?. Plugs are gapped at .8mm.

[blackrb20silvia]

what car what mods what engine???

the mass airflow meter converts the amount of air drawn into the engine into voltage signal . The ECU needs to know int6ake air volume to calculate engine load, this is necessary to determine how much fuel to inject into the cylinder.

this means that when the AFM runs out of scope there is no more fuel injected into the cylinder than there would be at full throttle so when the air flow meter reads full load its supplying the max amount of fuel so if the AFM cant read anymore air coming in it can not suplly the fuel for it to ignight so you basically run out of puff

so what you will feel is nothing just wont make any more power

but if the car is unmoddified you will never reach this point

people if this is incorrect please let me know this is my understanding of the opperation

of the AFM

[maximajim]

Rb25det/s14

Mods:

PFC

T3/t4 50 trim

Greddy plenum/q45 tb

3" dump

fmic

The car doesn't seem to completely stop making power, it struggles to reach redline.

I ordered a q45 AFM as it was dirt cheap ($65 USD).

[R33vit]

have a look at your PFC. Its will tell you if you maxed your AFM

[maximajim]

Where? ( i have the datalogit)

I've had a max voltage of 5.030 V, the max is supposed to be 5.1v?

[bluefire]

What are your fuel mods....

[maximajim]

stock injectors ~70% duty cycle. walbro fuel pump nismo fpr

[blackrb20silvia]

with the Q45 there is no way with those mods that you are maxing out your AFM get oyur car to a tuner and on the dyno and get your fuel and ignition checked and get them to test the AFM voltage and see if its reading correctly

[maximajim]

No, I just ordered one, I currently have the factory rb25 afm.

[paulr33]

yeah 5.0 volts is the max, or dead on. if its only a temporary max out its probably ok

but if its maxing out at like 3500 and stays at 5 volts the hole time then its a problem.

if its juts for quick second or two its no big drama. the ecu just wont see any more increase in airflow so more air is coming in than the airflow meter can measure

it doesnt feel like anything really. im maxing mine out, ive just got afm max warning turned off (flashes the engine light). im still on stock rb25 afm

[paulr33]

well if you have datalogit why not do a 0 to redline run (on a private road of course) in 3rd or 4th and then look at the datalog report, from there you should be able to see what goes spastic past 5000

[maximajim]

I have done a 0-100 run. At about 6000rpm maf voltage reaches 5v and and increases slightly to 5.030v at 7000rpm.

The problem is I've read the max voltage is 5.12v.

Well i guess I have to swap the maf to see if i actually do have a problem.