fuel cut?!?!?

[bobpogoman]

ok here is my setup:

ct-26 60-1 upgrade,
550cc injectors,
Lex Maf,
walbro fuel pump,
safc neo,
innovate motorsports wideband o2+ssi-4 (i can log rpm//a/f on lab-top)
aeromotive afpr,

im hitting fuel cut @ 10psi (boost controller to Minimum) when im trying to tune the car.

i can put some corrections without problem but at a certain point (im trying to tune the car @ 11.5 a/f ratio) i must put the correction at around 35% + at 6k rpm, @ 30% everything is fine, but @ 35 im hitting fuel cut (a/f go to max/11.5/max/11.5 each time i hit the cut.

is there something wrong? (i think, i dont think im supposed to be @ 35% correction @ 10psi??)

when i hit the cut, the check engine com on and off after 10 sec. i presume its turbo pressure abnormal, but i gotta check.

 

[Zumtizzle]

boost leak.

 

[bobpogoman]

i will check this, but is it possible to have such a big leak? and wouldnt i run extra rich? i must add +35% fuel @ 6000rpm.

 

[rayall01]

i will check this, but is it possible to have such a big leak? and wouldnt i run extra rich? i must add +35% fuel @ 6000rpm.

Big enough boost leak, and you run so rich, the car acts a lot like fuel cut. Bogs right down.

 

[bobpogoman]

im not running so rich, im trying to set the a/f to 11.5 @ +35% correction @6000 (normal a/f under boost) so im good for a/f,hitting fuel cut.. :X

 

[dumbo]

Duhhh check your codes.

It took longer for me to type this, then it would for you to check you codes....

 

[bobpogoman]

car is sleeping in the garaga ima do it tomorrow, but im 99.999% sure its turbo pressure abnormal (was doing it when i had fuel cut 2 weeks ago, when my fpr gauge was blown (showed 90 psi lol) now its set well thats y i havnt checked but i will dbl check tomorrow.

 

[CajunKenny]

The problem is your Lexus MAF!

Get a Lexus AFM in there and you'll be good.

 

[bobpogoman]

sorry for the typo, ive got the lex afm, not the maf the same thig as the 7m afm, but larger with an adjustement screw.

 

[bobpogoman]

confirmed, its the code 34, turbo pressure abnormal, also, i noticed that im hitting the cu always @ the same rpm (approx) 5200rpm in 1st 2nd and 3rd gear...

weird?

 

[CajunKenny]

sorry for the typo, ive got the lex afm, not the maf the same thig as the 7m afm, but larger with an adjustement screw.

Yep. I'm farmiliar with the Lexus AFM.

Weird...nope. Not unless you call boost leaks weird. That's where I'd start.

 

[bobpogoman]

ok, ima start making a boost leak tester... (ill weld a plate on an alu tube same size of my is piping since i got a spare piece...) then will block the accordian hose end and ima put 19-20psi of air in the system, it wont check for leaks everywhere, but will help.

but why i am not running rich ?

oh and im 100% sure i got lex afm, i measured the i.d. and o.d. of the round end as some one told me, and its a lex one.

 

[CajunKenny]

I wasn't doubting that you had a lex afm, I was poking fun at you for calling it a maf.

I had a boost leak and I didn't run rich. My boost leak was because a little plug on top of the trottle body blew out. It boosted and pulled great until around 11 psi.

And don't forget...we're all guessing based on the information you provide. They are educated guesses though.

 

[CajunKenny]

Also, code 34 refers to more than one thing.

Turbocharger
AFM
Intercooler System
ECU

Are you sure your lexus afm is good? Have you cleared the codes and hooked the stock one back up to see of 34 clears?

Intercooler system would be a boost leak.

Those are the easy ones...

 

[bobpogoman]

i dont have tho stock afm, the car came with the lexus one. (by the way where the adjustement screw should be?)

there may be a leak in ic piping, its a custom piping kit,that dosent have the bavel everywhere.all clamps are t-bolts.

i will start by looking for leaks then ill ask my friend to let me use his afm.

 

[CajunKenny]

Don't hold me to this because I'm not using a Lex AFM; but, I think I remember reading that the screw should be in the fully open position. Someone may correct me on that one...

Good luck and let us know what you find.

 

[bobpogoman]

i think this too, since the 25% more air is with it fully open, for the 25% more fuel. neway its just a little bit closed, almost fully open, i will fully open it and keep an eye on the a/f

 

[bobpogoman]

i was just thinking about something this wee-end, what if i had the stock fuel pump? it would keep up the 550s?

like theres not enuf fuel going to injectors, so i put like 35% correction to keep-up.

with 35% correction, im telling the ecu that it brings 35% more air in, this could make me hit fuel cut? since the ecu make the fuel cut with the air going throught afm..?

just an ide like that..gotta check if i really have a walbro 255lph,ima take my fpr gauge with a fuel hose in the car, so i can check if the fuel is keeping up @ 35% correction.

 

[rayall01]

I've seen people say they have the 550's working with the stock fuel pump, but you really are better off, with a Walbro, and an AFPR.

 

[CajunKenny]

You'll want to review this:

http://www.mkiiitech.com/forum/showthread.php?t=345&highlight=fuel+pump

I would also like to add that your fuel pump is 20+ years old. It's not wise to push it too hard.