Lean under boost!!

Complink · Oct 28, 2008, 01:42 AM

ok so i am having a problem with my fuel. i have tried just about every thing except checking the fuel pressure (don't have a gauge). When i first installed my 16g with stock injectors and ecu tuning, it would lean out bad like 17-19 afr at like 4 or 5 psi. then i put in a 12:1 fmu still on stock injectors and my fuel table's maxed out in ecuflash, and it would still come close to 13.5 or 14 afr at around 8 psi. Then i put in wrx 440s, scaled and tuned the trims and removed the reference line on fmu and its even worse. then i reconnected the reference line and tuned my trims and it wasn't much better than the stockers. at this point i was thinking it must be my TRE fuel pump so i got a walbro 255 HP and took off the reference line and its still hitting like 18 afr at wot at prob less than 5 psi. keep in mind my fuel maps in ecuflash are maxed out. I also noticed on a few of my old logs with stocker injectors and fmu my IDC wouldn't go past 64%. So i don't know if maybe my maf is the one to blame. i may have to fiddle with my maf scaling, but not quite sure how to do that.... Any suggestions?

i'd really rather not hook the fmu back up since this potentially causes the fuel pressure to go up to 120+ psi

TouringBubble · Oct 28, 2008, 08:41 AM

Can you post a pic of your fuel map? Aslo, are you editing the high or low octane map?

Complink · Oct 28, 2008, 10:17 AM

i'm doing both cuz i remember something about the only one used is the low, so i do both to be sure.

oh and im auto btw.

Complink · Oct 28, 2008, 10:19 AM

i will see about getting a log file if that will help

ambystom01 · Oct 28, 2008, 10:21 AM

Could it be that you're not reacting fast enough, ie. the car hits boost and thus leans out before the extra fuel is added?

Complink · Oct 28, 2008, 10:33 AM

well when im going about 45 and i punch it, my rpms jump to about 4 to 4.5 k and almost instantly its leaned out past 17 or 18 at near 8 psi. so i let off. im auto btw

Complink · Oct 28, 2008, 10:36 AM

at wot i won't start getting boost till about 3200rpm... then full boost comes about3.8 to 4k

ambystom01 · Oct 28, 2008, 10:40 AM

Sounds like a problem going from closed loop to open loop.

TouringBubble · Oct 28, 2008, 11:06 AM

Could be Amby ... you could try reducing the values in the Open Loop Throttle table for earlier onset of open loop.

Does the car act like it's lean? Are the plugs reading lean? Everything looks fine with the map ... maybe you have an exhaust leak or a bad sensor?

Yes, logs will help. Please include the stock O2 as well as the WB.

Complink · Oct 28, 2008, 11:48 AM

when its leaner than 16 it hesitates so yeah.

TouringBubble · Oct 28, 2008, 11:57 AM

What AFR are you reading in closed loop ... steady cruise?

Complink · Oct 28, 2008, 11:59 AM

well the only things i can think of thats wrong are:

1. bad fpr
2. clogged fuel lines
3. ecuflash problem

tommorrow im gonna go pickup a fp tester and see what my pressures look like

is it possible that my ecuflash is not flashing correctly? the rom info is:

lancer oz 5mt 03, ecu id

blank), case id

blank), internal id: 81900016, flash method: mitsukernel, memory module: sh7052, checksum module: (blank), inherits: 81900006

Complink · Oct 28, 2008, 12:00 PM

Quote:

Originally Posted by TouringBubble

What AFR are you reading in closed loop ... steady cruise?

it reads 14.7

TouringBubble · Oct 28, 2008, 12:07 PM

are the trims in check?

A test would be to slowly roll on to the throttle to 100%. If the issue is in the maps and related to open loop, you'll see the jump in AFR instantly when the crossover occurs.

Complink · Oct 28, 2008, 01:20 PM

ok so i have some logs. and don't mind the trims since it would do the same thing when i had them zeroed and the injectors scaled correctly.