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Old 04-17-2021, 08:47 PM   #1
Sonicfreak67
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Have a Nice Day? False knock or real knock on highway? W/ datalog

Hey everyone, after reading around here for a few weeks I am still concerned about my car's FBK, FKL, and DAM. I see consistent knock on the highway to the point where my DAM has dropped to around 6.8ish. I am on a stage 1 91 map. Only mods I have are accessport, SF intake w/ box, and an apexi n1 catback exhaust, car is 2007 MT WRX. My car's knock related values look good during city driving but once im on the highway I see values usually under 2.8, but here and there there are larger values (Yes i know cruise knock is common but also have read that if DAM drops it is concerning). It does not seem to make a difference if A/C is on, and i have filled up 3 times since i have noticed this issue (1 tank was 93 and it still persists). I did recently have a new clutch put in the car around 1500-2000 miles ago and it is chirping. Could this be causing false knock? That is the only immediately obvious culprit i can think of, but I dont see knock in the city so I dont know if this is causing the issue. I don't see knock during WOT pulls. I have since reset the ECU (stupid i know) so my DAM has been at 1 since but i have been avoiding driving on the highway enough for it to lower again. I have the data log of when i noticed the DAM lowered, it is provided below. Can anyone help here or give insight? I plan on getting a protune eventually when I put a downpipe on the car, i just thought it might be silly to buy a protune ona pretty much stock car. Any help would be greatly appreciated.



https://drive.google.com/file/d/1hOd...ew?usp=sharing
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Old 04-19-2021, 08:49 AM   #2
Jefe159
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The DAM drop is concerning, no matter what, especially knowing its not just bad gas.

If the only thing you're tuned for is that airbox it might make sense to slap the old intake back on and tune it back to stock - just to see if things are still acting up. You don't need a tune for the cat-back, so you could leave that on.

If that's not an option, at least call up a tuner and see what they say.
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Old 04-19-2021, 09:02 AM   #3
K3rm1tth3fr0g
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As stated above DAM is very important and you shouldn't drive the car while the DAM is constantly dropping. It means it car is knocking, like a lot.

I don't like the off-the-shelf tunes for cars over 30 to 40 thousand miles. There's just too much variability between cars for the OTS tunes to do a good job.

I would suggest finding a good tuner in your area who also does maintenance on Subarus and have them take a look and boost leak test the car.

And if you're already bringing it to their shop you might as well buy a used downpipe on Facebook Marketplace or on here and have them install it into in the car when they have it so you'll actually feel some substantial gains with your protune.

Oh and your stock DP can be resold for easily $1200+ for the metals in it right now.

Last edited by K3rm1tth3fr0g; 04-19-2021 at 09:07 AM.
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Old 04-21-2021, 05:56 AM   #4
MasterOfNone_
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Did this start happening after going stage 1? I'm no expert and just started learning how to tune on my spare time, but taking a look at your logs your timing seems really high and you're picking up fine knock as well. With the DAM dropping and fklc I'd say you're seeing real knock. Can you post another cruise log since you reset the ecu and a wot log in 3rd gear from 2500-redline?
I want to say that you have a tuning issue.
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Old 04-23-2021, 01:58 AM   #5
Sonicfreak67
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Quote:
Originally Posted by MasterOfNone_ View Post
Did this start happening after going stage 1? I'm no expert and just started learning how to tune on my spare time, but taking a look at your logs your timing seems really high and you're picking up fine knock as well. With the DAM dropping and fklc I'd say you're seeing real knock. Can you post another cruise log since you reset the ecu and a wot log in 3rd gear from 2500-redline?
I want to say that you have a tuning issue.
Alright I got on the highway for a short cruise. This time around I didn't see much feedback knock.

Cruise Log: https://drive.google.com/file/d/1xP5...ew?usp=sharing

3rd Gear 2500 - Redline Pull: https://drive.google.com/file/d/11Pz...ew?usp=sharing
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Old 04-23-2021, 02:02 AM   #6
AZ-GT
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Old 04-23-2021, 06:50 AM   #7
rtv900
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Quote:
Originally Posted by K3rm1tth3fr0g View Post
As stated above DAM is very important and you shouldn't drive the car while the DAM is constantly dropping. It means it car is knocking, like a lot.

I don't like the off-the-shelf tunes for cars over 30 to 40 thousand miles. There's just too much variability between cars for the OTS tunes to do a good job.
^lots of bad info here.

A) go ahead and keep driving the car all you want, just don't go WOT. These cars have enough power to drive right along in traffic at 30% throttle or less 100% of the time and basically no boost at all or a few psi at most. WOT is where detonation happens so it is perfectly realistic to drive it all day long and simply control yourself.

B) Mileage has less than nothing to do with an OTS tune, period. And 30-40K being the limit???? What? That's basically a new car. A tune is a tune, it's either right or wrong.
You have basically no mods, so if you are truly getting detonation you have something funky happening
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Old 04-23-2021, 10:46 AM   #8
K3rm1tth3fr0g
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Quote:
Originally Posted by rtv900 View Post
^lots of bad info here.

A) go ahead and keep driving the car all you want, just don't go WOT. These cars have enough power to drive right along in traffic at 30% throttle or less 100% of the time and basically no boost at all or a few psi at most. WOT is where detonation happens so it is perfectly realistic to drive it all day long and simply control yourself.

B) Mileage has less than nothing to do with an OTS tune, period. And 30-40K being the limit???? What? That's basically a new car. A tune is a tune, it's either right or wrong.
You have basically no mods, so if you are truly getting detonation you have something funky happening
I wouldn't drive a car with a dropped DAM more than I absolutely have to.

You can tell him to do whatever you want but the DAM dropped for a reason and he shouldn't just ignore it... That seems ill-advised.

And I am of the opinion that OTS tunes are by far the most optimal the less mileage the car has that is running it. I came to this conclusion after talking to many people running OTS tunes and helping ppl diagnose issues with their OTS tunes. You obviously can run an OTS tune with more mileage but the higher mileage the more change for variance in the car that can cause problems with OTS tunes specifically that don't account for variance between cars like a true protune would. Lastly I didn't say it was inherently dangerous to run an OTS tune, just that I don't like them from experience.

How many miles are on the car OP?

And OP I would email your logs to a reputable tuner in your area and get their help going forward.

Last edited by K3rm1tth3fr0g; 04-23-2021 at 11:35 AM.
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Old 04-23-2021, 12:03 PM   #9
rtv900
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Quote:
Originally Posted by K3rm1tth3fr0g View Post
I wouldn't drive a car with a dropped DAM more than I absolutely have to.

And I am of the opinion that OTS tunes are by far the most optimal the less mileage the car has that is running it. I came to this conclusion after talking to many people running OTS tunes and helping ppl diagnose issues with their OTS tunes.
ok, so don't drive yours if you have DAM drop. Detonation does NOT occur outside of heavy throttle high boost operation, so your opinion is simply to not do something despite it having literally nothing to do with an issue. You may as well say not to use your windshield wipers if you are having DAM issues.
WOT is the only applicable item to DAM and detonation.

And you realize that every single car that rolls off an assembly line (about 20 million anually) comes off with an OTS tune right?
So those tunes stop working right as the car ages?
sorry, that makes less than no sense. There's not even a shred of evidence that suggests cars need their tunes modified as they age.
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Old 04-23-2021, 12:19 PM   #10
K3rm1tth3fr0g
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Quote:
Originally Posted by rtv900 View Post
ok, so don't drive yours if you have DAM drop. Detonation does NOT occur outside of heavy throttle high boost operation, so your opinion is simply to not do something despite it having literally nothing to do with an issue. You may as well say not to use your windshield wipers if you are having DAM issues.
WOT is the only applicable item to DAM and detonation.

And you realize that every single car that rolls off an assembly line (about 20 million anually) comes off with an OTS tune right?
So those tunes stop working right as the car ages?
sorry, that makes less than no sense. There's not even a shred of evidence that suggests cars need their tunes modified as they age.
His dam dropped for a reason. Saying, just baby it and it'll be fine is not a good solution. It may keep it from blowing up at WOT but something is dropping his DAM

He should figure out why the DAM dropped.
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Old 04-23-2021, 02:16 PM   #11
rtv900
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Quote:
Originally Posted by K3rm1tth3fr0g View Post
His dam dropped for a reason. Saying, just baby it and it'll be fine is not a good solution. It may keep it from blowing up at WOT but something is dropping his DAM

He should figure out why the DAM dropped.
I never said just baby it, obviously that means he can never enjoy the car again.

I said it is perfectly safe to continue driving while he diagnoses it, particularly if he is like many people and only has one car. It is baseless to say it can't be driven in this condition as if it has a damaged timing belt or something.
It's 1000% safe to drive and just control one self and not use WOT while he figures it out.
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Old 04-23-2021, 05:50 PM   #12
Sonicfreak67
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Default False knock or real knock on highway? W/ datalog

Quote:
Originally Posted by K3rm1tth3fr0g View Post
I wouldn't drive a car with a dropped DAM more than I absolutely have to.

You can tell him to do whatever you want but the DAM dropped for a reason and he shouldn't just ignore it... That seems ill-advised.

And I am of the opinion that OTS tunes are by far the most optimal the less mileage the car has that is running it. I came to this conclusion after talking to many people running OTS tunes and helping ppl diagnose issues with their OTS tunes. You obviously can run an OTS tune with more mileage but the higher mileage the more change for variance in the car that can cause problems with OTS tunes specifically that don't account for variance between cars like a true protune would. Lastly I didn't say it was inherently dangerous to run an OTS tune, just that I don't like them from experience.

How many miles are on the car OP?

And OP I would email your logs to a reputable tuner in your area and get their help going forward.


The car is just coming up on 99,000 miles. I do not know when this started since I flashed stage 1 right when I got the accessport.

Last edited by Sonicfreak67; 04-24-2021 at 02:44 AM.
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