turbo problem i never faced
 

hi guys.
i turboed around 15 car in my life but i'm facing a problem i never faced before.
some of you know i'm turboing my winter beater aka the hyundai accent 1999.

here the car and setup.
hyundai accent 1999 1.5l sohc 12v , 302 000km
run like brand new before the turbo

CXRacing T28 turbo w/ 14 psi internal wastegate ( machined to 10 psi )
CXRacing blow off valve
CXRacing silicon couplers & clamps
CXRacing intercooler
OBX 8:1 fmu
GlowShift boost gauge
GlowShift oil pressure gauge
GlowShift wideband gauge

there no leak at all , i checked like 10 time.
i don't think it's related to the fmu because
1* plugged or not = same problem
2* 8:1 seem to be the perfect one for my goal and my stock injector.
3* tried with friends 6:1 and 12:1 = same thing
it may be the timing... but those engine have automatic timing wich is supposed to be good for 12 psi ( 7 professional told me )
the spark plugs are 1 step colder
spark wire are new from 2 month and are ok
ignition coil are ok too
i replaced fuel filter

the rpm just stay there ( over 4k ) , wideband hit its maximum value ( 20 ) , making no power at all , engine backfire , and oil splash out of the oil cap on valve cover when i release gas , so can't even get over 4 psi now.

with my experiance , if my ring was the problem , it would give problem without boosting... and without , it run like a brand new 2012.

at idle it is perfect. the only small trouble is when i rev it and stop , the rpm go under 300 rpm for half a second and come back to normal.

never faced this before and i don't know what is wrong there

Is it blowing oil out the dipstick or blowing the oil cap off? Either way if it is making that much blow-by there a serious compression leak somewhere. Maybe there was some metal shavings somewhere in the turbo setup that the engine ingested and trashed the rings. I would start with a dry/wet compression test first.

ok i will try to find a cpmpression tester tomorrow.
but if it was my ring , shouldnt my spark plugs be black ?
they are really clean and also looking the piston thru the spark hole nothing indicake a ring problem.

i'm wrong ?

Does the AFR go lean all of a sudden, or does it gradually drop off?

tough to say over the internet. post some pics. im suprised you turbod an engine with 190k miles on it...... the backfire is a lean condition, the lack of rpm increase is due to the lean condition. the engine doesnt have enough fuel(power) to increase revolutions over 4k rpm. if you hit 20:1 afr for long periods of time its almost a guarantee you damaged your pistons. the oil coming out of the oil cap is blowby which is going to be more prevelant on an engine with 190k miles.

if your hitting 20:1 afr then your fmu is not working or you have it hooked up incorrectly. an fmu is not a tune and should never be used when running more than 6 psi boost. fuel system component damage can occur when raising line pressure too high.


did you do the compression test?

fmu are MADE for up to 10 , not 6.
anyway the fmu is working great.
i got a fuel pressure gauge and its around 40-45 normal cruise and up to 80-110 ( dont remember exactly ) when the boost come. so fmu is working as it should.
the wideband go to 20:1 suddently ( when the rpm get stuck )
if i can get the engine to hit cutoff ( not WOT for low boost ) the wideband show around 14-15.5.

about compression test , i dont feel the need of it.
if i had lower compression it wouldnt feel like 92 hp but much like 80 or so.
i will do a test later for sure tho.


i found my problem.
my injector seem to be the original one from hyundai in 1999. they are going away.
when i found it was my injectors i called the shop i was working for and boss said its definitivly the injectors.
i will find 4 tiburon/elantra/sonata 1.8 or 2.0L injectors to fix the problem.
may take a long time as here junkyars only take 2008+ and i need 97-2006 injectors.

i wonder if 2.4L santafe injectors will be too big ? way easier to find.

Does that engine have a mass airflow sensor? if so that it your reason for hitting fuel cut off. You most likely maxed out your maf parameters causing fuel cutoff.
This is where things start to get expensive.
you will need larger injectors, larger maf sensor and a custom tune. If u get to this point then your fmu is no longer needed.
My suggestion is to continue to use the fmu and lower the boost level until the fuel cutoff stops happening. Had this problem with my 92 eagle talon turbo.

yes it has MAF sensor. first it was between the turbo and the air filter
and then now where it whould be as pro told me , on the piping between the intercooler and the blow off valve.
here in canada there alot og accent boosted and i dont know anyone that needed to get a better maf sensor. why would I need to ? can you explain ?
mine broke and i found a used working one ( took 27 days to find one ) for 35$. if i really need to i will replace it again for a better one but i don't plan to change it if its not REALLY needed.


also the wastegate is a 14 psi internal one. i opened it cut the spring and tested it until i get 10 psi , and welded it. i wont do it again because i had too much trouble welding it.

you think 2.4 or 2.7 hyundai injectors will be too much ??
because i can't find tiburon/elantra used injectors. too old for our junkyard.
but i already found 8 set of 6 injectors from 2.7 santafe and 2 set from a 2.4l santafe/sonata.

If you are trying to use upsized injectors, what will you be tuning it with?

Get the junkyard injectors flow tested.

the FMU.
i wont use electronic on a car i get rid after this winter.

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.

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.

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 ??

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 ???

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.

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.

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.

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.

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.

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

hi guys

im back after some hard days.

i did some test and cant find whats going on.

unplugged #1 sensor ( the one on the manifold before the cat)
unplugged #2 sensor ( the one after the cat and after the flex )
unplugged both 02 sensor
no difference at all.

i cannot even see check engine light ( had to completly remove it... did 8 garage , NO ONE could get a code out of it even if the light was on , even hyundai couldnt ). a known hyundai problem from 95 to 2002.

the fmu is really working.
i have enought fuel pressure.
garages said i had no issue about fuel even in boost ( pressure and debit )
they said pressure was a little high but thats was not the problem.

also 1 of those mechanic already boosted a 97 hyundai accent and had the same setup ( better quality..... but same system with fmu no piggyback etc ) and said he had no problem at 12 psi. blew it when he pushed it to 15 psi.

i called my prefered performance & tune shop and talked about my problem for the 5th time.

fuel cut is the only possible thing he can think of.
i asked him how much he could sell me a fuel pump and a aem f/ic... and the answer surprised me...

he said yes the aem f/ic will fix it but he wont sell me one because he is not a dumbass scammer. he know my situation and think it would be stupid to put that money on a car i get rid soon ( the tune = $$$$$$$$$ )

he is talking with other specialist at the shop to find the exact problem but he is sure ( like you guys ) the problem is fuel cut.

i could get a fuel cut defencer but.... with all that garages sucked me im left with 45$ free in my pocket for the winter ( yes i have bills to pay like you ) :)

fuel cut defencer = to forget. ( anyway ive got told its wrost than fmu )

isnt there a way to make one ?

any other idea ? i need my turbo car for the winter and cant get pricey parts until this summer.

EDIT
i think they was wrong about hyundai MAF.
im sure the maf is maxed out so the computer turn into limp mode.
bigger maf is a problem because im on a low budget and used hyundai parts are hard to find here.
so the only solution is a maf clamp.

but i have no idea how to make one.
anyone know ? or other solution ?

your getting rid of the car soon anyway so just lower the boost so fuel cutoff doesnt happen and have some fun with it. there is your solution.

the only other solution is $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$ cha-ching!!!!!!!!

dropped boost to 7 psi = same
dropped to 5 psi ( friend garrett t25 WG ) = same
not tried under 5... no one will ever set a turbo under 5 psi anyway...
i think i will modify my WG again for 5 psi and get a new external one for the elantra.

thanks anyway for your help

here some news.
even at 5 psi still the same problem.
added a tiburon 2.0L MAF , changed idle but still the same problem on boost.
1.5l or 2.0l injectors change idle but the same trouble on boost.

im lsot. i need the car to run good under boost until i get a SMT6 or FI/C.

is it still running lean? post pics of the car. i want to see how you have it set up. 5 psi with an fmu should not cause a 20:1 afr lean mixture.

i don't have pic of the final setup. but what have been done after those pic is the piping , better homemade vaccum manifold , and temporary exhaust fix.

Attachment 38930
https://www.homemadeturbo.com/attach...ine=1357709096
Attachment 38931
https://www.homemadeturbo.com/attach...ine=1357709096

post pics of the current setup. cant really see anything with these pics...

problem fixed !
maf clamp ( 4.3v zener diode )
i tried with 4.7v but fuel cut happen around 4.4-4.6v
im now running 10.3 AFR on full boost. a bit too rich but its better bein too rich than too lean :)
i put back the stock MAF so idle is perfect.

cost 2.93$ CAD

btw im surprized of the FMU stability. and there not even half a second delay for the fmu to work.

this thread is also another proof that fmu really work great ! sometime cause small problem but it work well.
for sure i dont go the fmu way anymore because parts price is almost the same as a piggyback without tune. if i get it tuned then ill still go with FMU because it cost way less and still do a great job. but as now i know i can tune it meself there no way i will work with fmu again :)