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Old 09-12-2021, 03:00 PM   #1
Scooby Newbie
Member#: 525837
Join Date: Jul 2021
Default 2017 WRX Consistent Knock and Dam Battle

Alright guys. I am usually on club wrx and here reading for answers with few posts but I'm struggling here.

Stage 1+ 8 months
New motor sitting at 60,000 km today oil change every 5000km 5w30 synthetic.

The car is reading -5+ FKL at times and FBK as well. The regular driving is minimal and I have stopped using ac since. But it's getting real anoying have dam constantly adjust. And it went as low as .4xx so I rode the car at +.35 FKL on the highway until it found its way back above 600 stayed out of boost got it to 900 and bam back to 600.

Anyways here is the mods(minimal) and troubleshooting

-Cobb intake
-Stage 1+ big sf tune

-Run tank dry multiple times and fresh 1/4 tank 91 from shell best we get no issues all year until this month
- clean maf
- new maf
- clean MAP sensor
- adjust intake and check for leaks (no smoke test done yet)
- new sparkplugs (did make a drive ability improvement but with battery disconnect that could also be because timing went back to 1 I assume)
-switch to LWG map for my car

(I had a code for rich to lean that hasn't come back since one re tune of ots big sf 91)
(I had a code for evap solenoid, turns out subaru tech pinched the harness at those wires in the intake manifold so I fixed the short throwing the code)
(Once I find the dam knock sensor I will try to angle it to 60***8304; and re torque it to spec. The engine swap mechanic was not my choice and I don't trust him)
(I have noticed a weird makeshift line running to the turbo I need to swap out for oem. I'll add a photo to a random folder)
(Heat shield on outlet side of turbo is rattling. Considering removing and blanketing turbo)

I want to figure out this new problem before getting phatbotti or lachute to etune for me.

Attached is a folder of logs, photos of the engine bay(its not perfect. I'm re painting the and saving the highmileage car from the previous owners neglect).photos of the car and other issues, photos of the accesport screen at various times. Some other irrelevant stuff for me. But if you go into data logs I name the logs yr/month/day and a brief description what the log was.


The reason for future tune will be to support stage 2+ mods reliably and not for to much power gains honestly. The car is quick enough but I really want to do the odd track days.

Irrelevent but to maybe good info for inputers advice the future mods will be iag aos and baffled oil pan. Exhaust, dp and up pipe. Not really interested in changing the turbo out unless I have to since I'm not.on a paper hunt just some budget fun and reliability.
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Last edited by unclefrosty; 09-12-2021 at 03:04 PM. Reason: Typo
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Old 09-13-2021, 05:04 PM   #2
Scooby Newbie
Member#: 525837
Join Date: Jul 2021

Hit -9.84 FBK today.
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Old 09-13-2021, 05:18 PM   #3
Scooby Specialist
Member#: 469585
Join Date: Jun 2017
Chapter/Region: W. Canada
2009 STi


Originally Posted by unclefrosty View Post
Hit -9.84 FBK today.
Not unheard of for FAís they have a very aggressive knock control strategy compared to EJís. Itís not uncommon for the DAM to fluctuate. If these events are happening at WOT, there would be more concern. But knock at low loads isnít a huge concern due to the low energy involved. My Stock Forester would see the occasion blips of knock up to 10 degrees at low loads and my DAM would fluctuate anywhere from .5 to 1. Granted we donít have the best fuel here, but itís just the direction Subaru went with the FA.
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Old 09-17-2021, 10:43 AM   #4
Scooby Newbie
Member#: 526607
Join Date: Sep 2021

Did you ever figure it out? I'm sadly going through the same problem. In my case I've noticed it more on higher rpm around 4000-4500. I will get FBK of -1.41 at 4000 rpm and it rises to almost -6 until I let of throttle. My DAM also dropped to .562
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