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Discussion Starter · #1 ·
I'm having an issue where my afrs seem to bounce up and down under WOT. This only seems to happen when the maf volts is around 4.2 or higher as when boosting in intelligent or sport mode it does not happen.

At this point I am fairly certain this is a mechanical issue as I have tried everything I can with adjusting the tune but it still jumps around in afr even though the maf voltage is constant.

I've done a smoke test and found no leaks


Mods:
Cobb catted downpipe
Cobb sf intake
Cobb FPR
AEM 340lph
ID1000 injectors
Turbosmart 40mm EWG
PLM EWG Up pipe
Grimspeed 3 port EBCS
IAG V3 AOS Competiton

Azure Rectangle Water Font Slope
 

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2006 WRX STi
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When was the last time you applied a tune? It reads like perhaps your machine isn't fully tuned (yet), so some components are "doing their thing" but are ignorant of the rest of your gear. Either that or your mods are relatively new, and the car hasn't "learned" them yet? (Last statement added in jest. Put those feathers down.)
 

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Discussion Starter · #3 ·
When was the last time you applied a tune? It reads like perhaps your machine isn't fully tuned (yet), so some components are "doing their thing" but are ignorant of the rest of your gear. Either that or your mods are relatively new, and the car hasn't "learned" them yet? (Last statement added in jest. Put those feathers down.)
The car is being actively tuned, this is not an issue that can be tuned out. During the areas that the AFR is bouncing the MAF voltage is constant meaning we cannot add or subtract any fueling between the high and low points. This is what pointed to it likely being a mechanical issue, probably something fuel delivery related.
 

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2006 WRX STi
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The car is being actively tuned, this is not an issue that can be tuned out. During the areas that the AFR is bouncing the MAF voltage is constant meaning we cannot add or subtract any fueling between the high and low points. This is what pointed to it likely being a mechanical issue, probably something fuel delivery related.
Fair enough. Fair enough. I figured that between the AEM 340lph and the ID1000 injectors you had that fairly well taken care of. Of course, there is only one other component involved, between the fuel pump and the injectors (i.e. fuel injector line), but wouldn't that result in a a constant effect, instead of the variation you are experiencing?

Heck, nobody else was bellying up to the bar, so I figured I'd throw in my $0.02 --- you know nothing attracts the super-effective help faster than when they get to correct somebody on the interwebz. And I figure I'm fairly wrong, now. I hope you can figure out what's going on, because I'd like to see this mystery resolved!
 

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Discussion Starter · #5 ·
No worries I appreciate the input. At this point I'm thinking it's either got to be the FPR not working properly or possibly that I need a fuel pulse damper in the system to help with this.
 
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