Can someone explain to me what knock feedback is? - Subaru WRX Forum
 
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#1 Old 03-17-2014, 12:30 AM
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Can someone explain to me what knock feedback is?

Thought I'd ask, I have noticed cruising that every now and then on my Accessport it'll show a -2.11 on Knock Feedback. Is that something to worry about? I have a loose heat shield that rattles like crazy at 2000 or so RPM's, could that cause it? I was also planning on doing a data log and sending it to Cobb as well as posting it up on here for more experienced Subaru owners to look at and analyze so I know whether or not my motor is healthy, etc. To tell you the truth I don't know what's bad and what's good. My 03 WRX is currently on the stage 1 91 octane Map. I have never heard it knocking just the normal ticking Subaru motors produce. It idles fine, no hesitation at all and no loss of power. I Don't generally take my car past 4k RPM's so I'm never really romping on it. Thanks guys!
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#2 Old 03-22-2014, 01:48 PM
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If it's anything like "retard"... it's the ECU pulling timing to compensate for something.

Fuel mileage, spark issue, fuel issue... etc...

And yes, rattling could set off the knock sensor. If you are worried about your motor, do a compression test and if they are out of spec... a leakdown.

Paul
2007 XT
2007 MS3
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#3 Old 03-22-2014, 03:17 PM
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Quote:
Originally Posted by pzr2874 View Post
If it's anything like "retard"... it's the ECU pulling timing to compensate for something.

Fuel mileage, spark issue, fuel issue... etc...

And yes, rattling could set off the knock sensor. If you are worried about your motor, do a compression test and if they are out of spec... a leakdown.
Should I take it to my Subaru Dealership to get a compression test done to see if they are out of spec?
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#4 Old 03-22-2014, 05:47 PM
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Do you get blow-by ?

Oil in the intake, turbo, tmic?

The #'s aren't ALL that important as the difference between them. For instance, if compression reads 135 in all cylinders.... you are ok...

If all read 135 and cyl 4 reads 100.... then you have an issue in THAT cylinder.

Paul
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2007 MS3
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