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Discussion Starter #1
Hey guys. First post here, I have an 18 WRX that I just did the perrin charge pipe and cobb big sf intake.

I searched but could not really find anything that really seemed like my issue.

I flashed the stage 1 + 91 cobb OTS, I am running 93. I am staying within +/- 8% AF learning 1 during regular driving. About 50 miles after flash. The issue is I am gradually going up to +25 at idle and if I blip the throttle it drops to around +3ish. as long as I have any throttle input or driving regularly im within the 8%.

I really have no idea what to look at, could it be a leak around the BPV, that Y hose was a pain on the perrin charge pipe.

Did a few pulls on 3rd WOT 2500 to around 5500rpm and boost is reaching target, td boost error within +/- 0.5 wastegate duty at 39 to 45, calculated load around 2.3, AFR at 11 ish avg with 10.73 to 11.9 range, af learning 1 at 2.34 most of the pull, got as high as 5.47 and af correction 1 ranging from 2.34 to 7 very randomly throughout the pull.

I also noticed that the 2 hoses in front of the BPV, that go to the inlet, on all WRXs ive seen its just two hoses. On mine, the thicker one has a plastic at the end of the thicker hose that has a wire connected to that I have never seen on any vid or instructions. it was almost like that does not seal, even before I first removed it to work on the BPV. What are those 2 hoses?
 

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Discussion Starter #2
Redid the whole install... lined things up better, cleaned the maf. Did everything I found could be a cause for it and it got a lot better but still occasionally jumps to +20s. Only 30 miles after reset learning. O2 not ready yet and evaporative not ready yet... gonna drive more. Anyone has any ideas?
Im about to go stock again. Not enough mods yet to pro tune. I was trying to hold off for bigger mods to be worth the $$$

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Discussion Starter #4
Not yet. Was thinking maybe a leak was the issue.


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I'll be honest. When it comes to the data logs I'm not the most informed person. What I do know is the fa20f tends to be more varied in the learning tables and timing changes than the ej engines due in part to the nature of direct injection coupled with the higher compression ratio.

I'd agree with your testing looking for vacuum and boost leaks. If those yielded no tangible issues I'd look to possibly MAF issues. Oiled filters tend to coat the MAF sensor in oil causing them to foul out. With those taken care of maybe ignition, or fuel quality.
 

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Discussion Starter #6
Thank you.... I always use the same station... never had an issue. Car has 11k miles only... only like 50 on an oil filter but anyway I cleaned the maf when redoing everything yesterday. Just emailed cobb.... ill post here whatever they say

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AF Learning is exactly that -- long term LEARNED fuel trims. These trims will NOT change during a WOT pull. In fact, they should be ZERO since the ECU will resort to open loop fueling.

If you want us to help, link a data log that clearly shows the AF Learning vs. MAF.

Even easier, there should be an option to read the AF Learning cells individually A, B, C, and D. Post those in here. If you have pegged your LTFT at 25%, something is wrong. It is normal for LTFT to fluctuate due to environmental and fuel quality factors as well as fuel ethanol content.
 

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Discussion Starter #8
I jst read it shouldnt go past +/- 8 so got scared. It fluctuates to 25 ish but drops as soon as any acel input is made. during wot its 0, afr looks good... no knock... boost is ok within map notes.... I will log A B C D and maf voltage wot and post it here for peace of mind.... this is my third wrx but first one that im modding so still a complete noob. Thank you for the help. It is true when they call the accessport ANXIETY PORT... when in the hands of a total noob LOL

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There should be no Learning or Correction during WOT as this is open-loop fueling. On the older platform, the D cell learning was applied as a correction for OL. I don't know if that's the case, but everything seems normal EXCEPT that idle is close to 25 LTFT.
 

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Discussion Starter #10
There should be no Learning or Correction during WOT as this is open-loop fueling. On the older platform, the D cell learning was applied as a correction for OL. I don't know if that's the case, but everything seems normal EXCEPT that idle is close to 25 LTFT.
Yes... it all looks good as far as I understand but it creeps to positive 20ish only under idle stopped no accel input. If i blip the acel it drops to within 8% ... I will get logs tonight probably... I also have someone at cobb helping.... he is saying maybe a leak or bad maf but maf is 11k miles and cleaned with maf cleaner. I have one spot where im concerned about a leak but its how it was stock....

In red is where the bpv goes, yellow not sure maybe vacuum hose it looks fine, in green all the other wrx ive seen have a hose clamped to it. Mine has a plastic piece at end of hose with an O ring and a cable connected to it. That one seems like its loose but its how it was stock no issues... I have no ideia what it is.
20200903_154905.jpg
20200902_205402.jpg


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Discussion Starter #11
Cobb asked for a wot 3rd gear pull 2500 to 7k and about 2 minutes idle once up to temps... ill post them here too.

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This piece is a sensor that is meant to detect vacuum leaks in lines. You're saying that there is no CEL? It should be plugged into a vacuum source.

326074
 

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Discussion Starter #13
Sensor is plugged... tested continuity on the cable make sure I didnt break it.... it goes into the green port... no CEL

The fit feels loose.... for the o ring but thats just how it felt before I removed it first time... theres like a green o ring inside the white plastic piece... couldnt even find them online on subaru parta to see what they were

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Discussion Starter #14
Looking it up for hours... found a perrin manual that says its a crankcase hose and pcv valve. Im trying to find a replacement just to get it off my mind as a possible vacuum leak spot but I cant find it at allllllll in the su aru parts page

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Discussion Starter #15
Still with someone at cobb, no solution. Here are the logs I sent them.
Idle, datalog4.csv
Idle, datalog1.csv

Cruising and 2 pulls from around 2500 to 6000.

I am trying to clean and re lube the filter tomorrow, maybe less oil than it came stock. Clean maf AGAIN, check o ring, check maf extension and apply dielectric grease.

I did go through it all a third time, could not find anything wrong, sprayed a LOT of starter fluid around the hoses I worked on, no leak that I could find at least.

So frustrating. Hope I can get it right.

Thank you guys for your time.
 

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Discussion Starter #16
No opinions at all?
After taking it apart and putting it together 100 times making sure there were no leaks... af learn numbers are now around 10+ while driving around, 14+ while driving hard. It zeroes out at idle. The person from cobb support sqid that it was normal... also.. o2 sensor not ready at almost 2k miles after flash... im about to just remove it all.

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Me either. If I were in your position, I would reinstall the stock intake and stock map and see if my LTFT go back to "normal."

At this point, it could be anything from a bad O2 sensor, bad MAF sensor, undiagnosed vac leak, or even bad manufacturing tolerances for the intake.
 

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Discussion Starter #19
Doubt a bad sensor... car is 13k miles... doubt I have any leaks... re installed so many times making sure all was good and testing for leaks... im calling it quits.... F this intake.
Im going back stock tomorrow... and ots stage 1. Hadnt had any issues before going stage 1 +. Wanted to keep the noise but honestly... it was actually already getting old. Not worth running crazy trims... systems not going ready....


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Doubt a bad sensor... car is 13k miles... doubt I have any leaks... re installed so many times making sure all was good and testing for leaks... im calling it quits.... F this intake.
Im going back stock tomorrow... and ots stage 1. Hadnt had any issues before going stage 1 +. Wanted to keep the noise but honestly... it was actually already getting old. Not worth running crazy trims... systems not going ready....


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With an aftermarket intake? Absolutely could be a fouled maf sensor, welcome to the world of oiled filters. If it isn't fouled now, it can be later as the oil gets sucked off the filter into the intake.

It's worth cleaning it and checking. Without actually testing anything it's extremely hard to tell if there is a leak based only off of install reinstall cycle.
 
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