Had the car tuned a few months ago, spiking at 28psi and 11.5-11.7AFR's. Put on a new synapse bov about a month ago since the stocker was leaking. Boost went up to a spike of 30psi but AFR's fell to a pretty steady 11.4-11.5 at wot in a 3rd gear pull. I turned it down a tad and let it be.

Now the car sat for about a week and yesterday I take it for a ride (it's been cold now like less than 35 degrees). Boost spikes to about 30 and AFR's in the 12.5 range! I now have the boost turned all the way back to the 26psi range but it's still in the 12.0-12.1 range which i'm not comfortable with.

I need to hook up the laptop to see if there's any knock, but in the meantime...what could've went wrong??

General power Mods:

Forced Performance RED Turbocharger
Forced Performance Intake Pipe
Perrin Air Filter
Megan Racing 02 Housing
AMS 3" Exhaust
AMS Front Mount Intercooler
AMS Lower Intercooler Piping
AMs Manual Boost Controller
Fujita Upper Intercooler Pipe
Keflford 272 Cams
ARP Headstuds
Buschur Racing Ported Exhaust Manifold
Synapse BOV

 

Log it is it running out of fuel

Pump
Injector

The colder weather will def make the boost spike little more sometimes but. Backing it off to 26 psi from where it was tuned and it's still lean. Good idea to log it and you'll get a better picture

 

It has a walbro and 1050cc injectors so it shouldnt be out of fuel. Just wierd that it happened out of nowhere....

 

just lower your boost by 2psi. Could be due to cold, so you may go over the map. make sure the car is fully warm before you log it. Im around 12 as well, and it was 11.4-5afr at 25psi, but i love how the sucker pulls in cold weather :>

 

Injectors could be scaled wrong, making fuel trims off and AFR during WOT drift/change. This take a lil time, which could explain why it was ok at one point.

Also, was your MAF scaled for you intake pipe?

 

check your fuel pressure regulator vacum line.

 

Another good idea

 

It could be hitting different load cells now that you played with the boost.

 

+1

 

Checked the FPR lines and there all on and zip-tied. Injectors were scaled for sure.

Well how do I find out if it's hitting different load cells? I have it down all the way to 25 psi and it's still over 12:1. Turning down the boost does not seem to be helping at all anymore....

I mean I know it was tuned for a 28-29 psi spike, so I could just turn up to that, but I don't want to keep doing WOT pulls with the car so lean.

 

Did you log fuel trims???

injector can be "scaled for sure" but that doesnt mean their %100 correct. You have to log your fuel trims and see if they drift. If they do, they need work.

Also turning down the boost wont help because fuel tables are usually setup so that more boost(LOAD to be more precise), results in richer AFR and less boost (less LOAD), a leaner AFR.

 

LTFT doesn't effect WOT AFR. so once its tuned to 11.5 it wont drift from there assuming everything else is good to go. so that rules out injector scaling as the cause of the lean WOT.

things to check:
vacuum line on fuel pressure regulator
MAF screen intact?
all the hoses on the intake side of the turbo connected properly?
injector duty cycle, if you were close to 100% before, temp getting colder could put you over the limit... i would consider this after the other things above.

 

Have you replace the intake lately? I had this happen to me when I couldn't find any cone filter to fit my Injen adapter so I bought some K&N and made my own filter. Suck a lot more air causing the lean. I went and got HKS megaflow and it is back at 11.2-11.5. GL Possible boost leak?

 

I have never experienced it myself (injector scaling messing up WOT AFR), but Naji once found that his WOT AFR was changing/drifting a week or so after tuning and found that fixing injector scaling made the AFR not change/drift and stay consistent.

And +1 on the injector duty cycle.

 

I'll check the maf in the morning.

I have lots of counts of knock sum (6-8). I don't actually know how to check the injector duty cycle. Hell I don't honestly what most of the stuff I just logged mean.

If it's it not the MAF screen then i'll just have to take it to a shop that knows what there doing, just sucks living in a smaller town and not having anyone local that works on evo's.