SR20DET running lean at WOT? what's up?

[delado]

Hello lads,

So I finished swapping a red top sr20det into my kouki about 2 weeks ago.

Car runs great and have absolutely no problems. I installed a brand new AEM UEGO wide band a couple days ago and started to worry a bit because my AFR's seem off.

Idle numbers are good ~13.4

Cruising numbers are good ~14.5-15

WOT ~12.5.-12.8 <---- WTF?

I'm running stock boost ~7-8 psi sometimes spiking at 9 when cold out.

What could be causing this?

Mods (all parts are brand new):

stock 62 ecu with the correct skinny O2 sensor.

Walbro 255

FMIC (no BOV)

WS engine harness

PBM cobra DP

HKS hi power exhaust

test pipe.

Things I have checked:

No exhaust leaks

swapped out my SOHC maf with a friends SOHC maf (no change)

Any ideas as to why this may be happening? :sadwavey:

Is 12.5 a danger zone? Like for serious danger zone? I'm confused because I'm pretty sure stock SR's with a walbro and stock FPR run pig rich,.

I usually do pulls in second and third gear and by the time I get to top end the lowest number I'll see is about 12.5

Motor was pulled from a automatic front clip with like 36,000 km

[fliprayzin240sx]

Did you double check the base timing? Maybe the CAS got bumped....

[delado]

Did you double check the base timing? Maybe the CAS got bumped....


Didn't check timing but I will say that the bolts that hold the CAS still have the sticker on them with Japanese writing on them (i'm assuming they slap those on to ensure nobody is messing with the CAS).

But if timing was off wouldn't the car run like balls all over the place? Like mentioned, if I didn't install the wideband, I'd think everything is fine and dandy.

[fliprayzin240sx]

Double check your base timing, 12.5 AFR is high. If it was 12 on WOT, I wouldnt be too worried about it. What fuel pump are you running?

[Dboyizmlg]

Your wiring for your fuel pump can also cause this issue.
I would suggest you check the voltage for the power wire going to the fuel pump.

If I recall correctly the voltage should be a solid 12V.
Any thing like 11.5v and under will cause it to lean out.

[delado]

I'm gonna check the voltage today. And the pump is a walbro 255.

[Dboyizmlg]

I wired in a relay just for the fuel pump on my S13.
Here is a link for you.

http://www.ka-t.org/forums/viewtopic.php?f=12&t=59949

You're S14 might be a little different though

[delado]

Well I went and picked up some MAF cleaner and sprayed the maf. Getting 11.2 at WOT.

[Boostd2]

ahh, the classic dirty MAF trick.
Probable time to replace the air filter?