busa4

boosting a maf car can be done but with the stock tune you cant boost much before you hit fuel shut off. there maybe a lot of accents boosted in your area but you dont know what they did to set it up. your obviously hitting fuel cuttof and there is nothing you can do to stop it except lowering the boost or getting a custom tune. if you install larger injectors then you will need a tune. theres no way around it. most japanese tuners use general motors 3" maf sensors because there larger and they can read more airflow. this will prevent fuel cutoff but a tune is still needed in order for this too work.
any major change to the fuel system or sensors will require a tune so your best option is to continue using your setup but lower the boost untill fuel cutoff stops happening. this is your only option unless you want to spend a lot of money.

Matt Cramer

Backing down your fuel pressure with the oversized injectors will get rid of the whole point of installing larger injectors. I agree with Busa4 - it sounds like the claim that the stock ECU is already tuned to run correctly in boost appears to be wrong.

HyundaiTuner

sorry for late answer.
i finaly got bigger injector ( tiburon 2.0l injectors , ALL said its the best )
cleaned them up with comrpessed air and injector cleaner. they was really clean !
the fmu , once again , is working right because when riding normaly , my fuel are around 40-45 and under boost it go up to 120.
now i can hit like 5-8 psi sometime.
still cant hit 10 because the problem is still there.

unplugged fmu = same thing
unplugged stock fpr = same thing

no boost/vac leak

i understand what you guys say about fuel cutoff.... but the FMU is working and add pressure ! so what about it ?

my curent AFR under boost ( from 1 to 7 ) is around 14:1 , same as normal drive.
14:1 from 1 to 7 mean the fmu is working. if it wasnt working , i would go leaner as the boost go up , no ?
yes its too lean but i need to find the problem before getting another fmu calibration.

by the way... why my stock FPR do no change at all when unplugged ??

HyundaiTuner

EDIT :
did a long ride with no fuel management ( fmu ) without boosting.
came back home , put back the fmu.
now i hit 8-9 psi and wideband show 16:1 - 17:1 and never hit 20:1+ like before.
no idea what happens but the problem seem to be fixed !

yeah , still way too lean but at least now that i know the problem is fixed i can change the calibration disc.
i have a 8:1. wich one i need ? 6:1 , 10:1 , 12:1

busa4

u dont want to go any higher than 6 psi boost with an fmu. if you do, your over-stressing your fuel system components and they will fail. finding the correct fmu ratio for your engine is trial and error. always start with the richest setting and work your way leaner. as of right now your running dangerously lean and you will destroy the motor. you want to be at 11.5:1 afr under boost. without a tune your stock computer is going to try its hardest to keep the afr at 14.7:1 no matter what. if you want more than 6 psi boost then shitcan the fmu, get larger injectors and then get it tuned. this is the best way to have a reliable turbo'd daily driver.

HyundaiTuner

i see a lot of car here running 12 psi with a fmu... i would'nt run that because fmu are know for 10 MAX but they have no problem.

i understand your point about pressure and you are right.
but there a big problem....

there is NO WAY i will pay 450-800$ for a tune in a car i get rid this spring.
i could buy a aem fic as its universal and will fit my futur elantra.
but the tune is engine/setup specific. that mean if i tune it for my 1.5 , it will not work for my brother 1.5 ( same engine , same turbo , same boost ).

this is the problem.

busa4

your fmu maybe working but is your fuel pump? most stock fuel pumps cannot handle 3 times its normal operating pressure. as pressure increases, volume decreases. they make a pump specific for higher pressures that maintains high volume.
an 8:1 fmu should be ok. that 8 psi fuel pressure for every 1 psi boost. your applying 80 psi more pressure over static pressure so in turn your fuel rail at 10 psi boost is at ~120 psi......... i can guarantee your factory fuel pump cannot handle this. also injectors can get damaged trying to open with this much fuel pressure. they will over heat and in some cases they will just stay open. im not sure what else to tell you but if you keep driving the car with 16-17:1 afr under boost your only going to have a boat anchor. i have no more usefull info to give to you so i wish you the best of luck on your build.

jdchmiel

Sounds like your car is hitting a limp mode when the MAF reads too much air for what it expects. Maybe a voltage clamp will keep the ecu from flipping out. You cannot trust the wideband numbers if it is in a weird limp mode where the timing might be so far off that fuel is still burning in the exhaust.

HyundaiTuner

never heard that when pressure increase volume decrease.
i know for sure my fuel pump give enought pressure ( dont know about volume )
so a walbro or a cheaper 255lph in-line fuel pump should fix the problem ?


called a hyundai specialized tuner and the stock MAF can handle it with no problem.
and anyway if that was the case , it would make a difference when i place it between the air filter and the turbo. but there NO difference.
also the 2.4L santafe use the exact same MAF. this engine breath twice as the 1.5L so i don't think my MAF is the problem.

jdchmiel

you misunderstood me, the MAF might not be maxxed out, but the ecu might only allow a value of say 3.5v before it says wtf. Good luck