1jz goin lean at 6k

[ahmed]

ok i have a 1jz in my sc300. i did a boost leak test and it passed. on full throttle the car goes from 10.5 to instant - - - lean on the wideband right before it hits 6k. its an aem wideband and only has 200 miles on it. i unhooked the battery waited 10 mins and plugged it back in to reset the ecu and still didnt help.. also i have new plugs gapped at 28......

anyone got an idea on what it is..

 

[tissimo]

What fuel pump do you have in your car?

 

[ahmed]

stock. but i have a tt fuel pump i can throw in but i dont have a fpr is that ok.

 

[tissimo]

The stock fuel pump is too weak. Replace it with the TT and the problems should go away. Itll be fine on the stock FPR

 

[ahmed]

ill swap it out and let you know if it solved it.

 

[ahmed]

put the tt pump in now car wont run. it will start then 5 secs later die. hitting the gas dosnt help.

 

[86_sports_1jz]

the fuel pump could be flooding the motor but i don't see how that would be if you are still on the stock fpr. you have any tunning device? also make sure your wideband is working right cuz i had a similar problem and it ended up being my wideband craping out on me

 

[dslocal]

Do you have fuel pressure after the car has been running? When you turn the key "on" the fuel pump primes the motor to start, It will generally run for a couple secs before it runs out of fuel if the pump doesn't keep going,
If this is what happens then it means for some reason the fp isn't pumping with the engine running... Can't think of why that would be right now.

 

[ahmed]

i had to wires constant battery voltage to the pump and car runs fine.
i did a 2nd gear pull and i used to be at like 10.5 with old pump with the tt pump it was so lean. i did a couple pulls and car was so lean in all rpms with the tt pump.
my wideband is brand new.

 

[tsupra]

did the vacuum hose become disconnected from the fpr?

 

[86_sports_1jz]

is the fuel pump still good? you should double check to make sure the wideband is calibrated correctly

 

[ahmed]

fuel pump is mint onbly 2 months old came out of my buddies 500hp sti.
wideband is brand new all i did was take it out of the box and install it.

 

[ahmed]

stock fpr has the vacuum on it and stuff. tt pump is good. car pulls very strong and fuel ratio is good till high rpm a 2nd gear pull car goes dead lean right near 6k a 3rd gear pull car feels like it hits a wall at 5500 and goes lean at same time.

 

[ahmed]

anyone have any ideas.

ima fill it with 110 octane and see what happens. then ill install a boost gauge and see if tis running stock boost or if for some reason its very high. anyone else got any input. i never touched the timing on the car could that be it.

 

[Nopaint]

boost cut?

 

[ahmed]

ok with race gas car hasnt hit the wall feelin but still goes lean... car runs like 10.5 till high rpm then goes - - - lean.

 

[dslocal]

could it be your getting spark cutout?
My reasoning is that if the spark starts cutting out then you will get your wall feeling and because your mifiring and there is extra unburnt 02 in your exhaust it will read lean?
What are your plugs gapped at and what kind do you have

 

[ahmed]

ngks. at like 28...

 

[ahmed]

this is driving me crazy.

no boost leaks
ngks at 28
tt fuel pump.
14-15 psi boost
3in full exhaust.

car runs mint. no issues. only at high rpm gauge goes from 10.5 to - - - lean instantly. i have no idea why.
with race gas i havent felt the o shit i just hit a wall feeling. i just filled up with shell 93 and ill see if it does the wall feeling.

can it be my fuel pressure regulator. or maybe the power source to fuel pump just dies at high rpm. or maybe 28 is too high of a gap. thats all i can think of.

 

[tsupra]

this is driving me crazy.
can it be my fuel pressure regulator. or maybe the power source to fuel pump just dies at high rpm. or maybe 28 is too high of a gap. thats all i can think of.

easy way to check these things. hook a fuel pressure gauge up so you can see it while driving, if it's a mechanical gauge don't run it into the cabin with you. if fuel pressure drops on the top end then you need to check over the fpr or fuel pump. if the gap were too much you'd have spark blowout and should see a rich condition. if you are hitting fuel cut, that hitting the wall feeling, you'll see a sudden spike in fuel pressure right at that instant.