Isolated Lean Spike

[mischief7m]

Hey All,

I recently got my PLX wideband installed, and properly tuned my safc.

it runs perfect through almost the entire rpm band, whether i am under boost or just cruising, except for right from 2000-2150 RPM on the low throttle setting of the SAFC.

Under normal (not WOT) acceleration i get a spike of about 16.8 on the wideband, peaking at about 2075 rpm. then right at 2150 it goes back to normal.

If i add fuel at 2000 rpm, i can get the lean spike to get into the normal 14.7 range, but then everywhere else around there i am running too rich.

My mods are 3" cat back,
2.5" ic piping and frontmount
USDM 550's
afpr at 32 lbs (vac off)
255
apexi safc

i have a few others, but not that would effect fuel delivery.

I am running the 550;s because the only harness i could get my hands on at the time of the swap was already wired for them. that is why i am running a lower fuel pressure.

with the safc on low throttle i am pulling:
Nothing at idle
2000: 7%
3000: 11%
4000: 12%

and the rest doesn't really matter, because there are no problems up there.

if anyone has any possible suggestions, or answers, i would love to hear them.

also i was wondering if it is even much of a problem, since it is only in low throttle, i am not pulling hard, and since the max i have ever seen it spike was 17.0 (it never says lean). it may be no big deal, and if thats the case i won't even worry about it.

thanks in advance,
-Trevor

 

[Bigzavs]

my friend had a similar issue, try upping your FP to 43psi w/o vacuum (stock) re-tune and see how it does

 

[mischief7m]

i'll give that a shot, im just not sure how im going to tune up high, because i am already pullling 25% up high.

 

[fstlane88]

What ended up happening with this? I just ran into a very similar issue.

 

[GotTurbos?]

I had the same problem with my car, except at 3000rpm, I was running 41psi of fuel pressure instead of the stock 43psi, turning it up to 43 and some work on my safc and I was able to smooth it out. I want to say this is pretty normal as it seems to happen to a ton of people. It seems like a problem, but just add fuel in that area and you should be able to get it to where it is completely smooth.

 

[mischief7m]

i tried tuning it out, and it just pushed the spike higher up. i upped the fuel pressure, and nothing...the other odd thing is that when i am driving, my AFR's get richer when i let off the gas and get leaner when i get on it.

i understand this is backwards...is it possible that the throttle setting on the safc should be the down arrow instead of the up arrow?

but i also believe that i have one bad injector, so that may also add to the problem.