Loud Knock starting out of nowhere, Please Help, need advice - Subaru WRX Forum
 
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#1 Old 07-09-2012, 10:02 AM
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Loud Knock starting out of nowhere, Please Help, need advice

So i was driving home from my parents house last friday and it was a really hot day(about 100 out) i stopped at the gas station filled about half way up and when i pulled out and up to the first light my cel started flashing. pulled out the code reader and pulled the codes p0301 and p0172. so i continued driving home after clearing the codes to see if they would come back on, they did not. As i was getting home i heard a faint ticking noise that would come and go. i didnt think much of it since these engines are pretty loud already. as i got home i was downshifting to turn down the street and out of no where a knocking noise started. i coasted down the street and shut off the car just to make sure i didnt damage it. started checking it out(i am a mechanic so i have some idea of what im doing) and it had a knocking noise coming from under the throttle body. put it in the garage and did a compression check on cylinder 1 and 3. found 75 psi in cylinder 1 and 125 in #3. did a wet compression check on cylinder 1 and it went up to 120.
Also there seemed to be dirty water or oil in the intercooler tubing as well as around the turbo. the air filter is pretty dirty but unsure if it caused the problem. the last thing i noticed was a little bit of oil dripping from around the turbo. havnt investigated it yet but will probably do so if i have to replace the engine.

That is where i am at right now, i am fearing the worst that it will need a new engine but i am hoping someone can at least give some usful advice as what to check to confirm exactly what it is. Im not very firmiliar with these engine. anything will help, thank you.

2002 Subaru wrx 2.0 all stock except hks bov and intake in fender. clutch and flywheel replaced 5 months ago, a month after i bought the car.
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#2 Old 07-09-2012, 10:17 AM
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Why didn't you do all the cylinders? Prob a bad batch of gas (longshot)

Was there anything in the IC prior to this?

You need to clean everything under there including replacing the PCV.

How many miles are on it?


EDIT: Are you running the BOV VTA ?

Paul
2007 XT
2007 MS3
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#3 Old 07-09-2012, 11:24 AM
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it was just a quick check to see the difference between the 2, i can check the other two aswell. it has 133k on it and idk what vta means
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#4 Old 07-09-2012, 11:54 AM
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Vent to atmosphere. You have the stock BPV (bypass valve) still ?

Clean the MAF sensor yet?

as far as the oil near the turbo, it might be the banjo bolt to the feed line. How is the oil level?

Paul
2007 XT
2007 MS3
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#5 Old 07-09-2012, 12:31 PM
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nope no stock bov. the maf sensor was pretty dirty, it was coated on one side. and as for the banjo bolt i know what your refering too but i believe the turbo has to come off to access it. which is a possibility in the future but im a little more concerned with the loud knock in the lower end
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#6 Old 07-09-2012, 01:37 PM
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Can you post a vid with audio to see if it's really knock?

Paul
2007 XT
2007 MS3
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#7 Old 07-09-2012, 03:31 PM
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ya but not for a day or 2
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#8 Old 07-09-2012, 07:43 PM
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Is the car tuned for that intake? Could have caused a lean condition making for a bad day...boom.

Kevin.
Cobb ap stage 2 ots, catless uppipe, catless turboback, Cobb Sf intake.
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#9 Old 07-10-2012, 11:06 PM
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You mentioned having your intake on the fender. Is it possible that you sucked up some water into the engine? That happened to a friend of mine who had a RX-7 with an LS1 transplant. It made an impressive hole in the engine block.
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#10 Old 07-11-2012, 12:28 AM
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Clean your MAF.

I don't mean wipe the fuz off the IAT snsor that shares the housing - clean the MAF wire up inside the sensor!

Brake Cleaner/MAF Cleaner sprayed at the wire, don't dare touch it, you'll fudge it up fo-sho.

S
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