Cobb Stage 2 OTS Map. Feedback knock? - Subaru WRX Forum
 
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post #1 of 3 Old 07-29-2014, 12:11 PM Thread Starter
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Cobb Stage 2 OTS Map. Feedback knock?

It was rare that I got Feedback knock on the stage 1 OTS Map. On the stage 2 OTS Map I've been getting -2.11 almost everyday this week with occasional -4.22. I have a Kartboy Pitchstop mount and Group N transmission mount with Kartboy Bushings all around which made the motor a little noisier. Could the Knock sensor be picking up False Knock? It runs fine, no loss in power, no check engine lights or misfiring.
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post #2 of 3 Old 07-29-2014, 02:17 PM
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The knock sensor is essentially a very rigid microphone, It might be picking up the extra noise from the new bushings and the pitch stop but if the knock wasn't present before you switched to stage 2 then there might be something going on with your stage 2 tune.

If there was no knock on your stage 1 tune and all you changed was the OTS stage 2 tune then I would switch back to stage 1, or try one of cobbs other stage 2 tunes. It is also possible that you have a bad tank of gas or that your tune might be over boosting causing some pre ignition. Pre ignition is normally followed by knock and both are bad juju. The knock sensor is designed to read any abnormal burn pattern in the cylinder. so its not something I would let go for too long.

Have you done any logs latley? Maybe if you can put down a good 3rd gear pull we can help you figure out why the knock suddenly showed up. Just make sure you post your map details and your mods list with your log.

hope that helps

Jason
13 WRX Hatch - Cobb OTS Stage 1
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post #3 of 3 Old 07-29-2014, 08:40 PM Thread Starter
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Originally Posted by arcticscythe View Post
The knock sensor is essentially a very rigid microphone, It might be picking up the extra noise from the new bushings and the pitch stop but if the knock wasn't present before you switched to stage 2 then there might be something going on with your stage 2 tune.

If there was no knock on your stage 1 tune and all you changed was the OTS stage 2 tune then I would switch back to stage 1, or try one of cobbs other stage 2 tunes. It is also possible that you have a bad tank of gas or that your tune might be over boosting causing some pre ignition. Pre ignition is normally followed by knock and both are bad juju. The knock sensor is designed to read any abnormal burn pattern in the cylinder. so its not something I would let go for too long.

Have you done any logs latley? Maybe if you can put down a good 3rd gear pull we can help you figure out why the knock suddenly showed up. Just make sure you post your map details and your mods list with your log.

hope that helps
On the Stage 1 OTS Map I would get a -2.11 a couple times a week. -4.22 showed up a couple of times running that map as. The -4.22 was always occasional, about the same as the Stage 2 OTS map(only shown up twice on the Stage 2 map). The -2.11 happens most of time in between shifting or starting at a red light, going from a stand still basically. I don't think I'm over boosting. I'm only making 9.88 lbs. My waste gate is messed up or I have boost leak just haven't gotten around to figure out exactly what it was. I did have the bushings and mounts on before going stage 2.
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