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Old 07-08-2003, 12:54 PM   #1
renichms
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Member#: 38550
Join Date: Jun 2003
Location: Birmingham, AL
Vehicle:
2004 Impreza WRX STi
WR Blue

Default Knocking question

Some STi's are said to have detonation problems. Thus far, I have no had any. Online I heard a recording of an STi knocking. Today, I put the pedal to the floor in 6th gear and at the highest boost I achieved, I heard a VERY faint sound exactly like that in the recording, so I tested again and got the same thing.

Is it possible that this isn't detonation? Is it possible that it could only be under high boost in 6th gear only? I've not heard it in any other gear but suspect that may be because of how loud the engine is...but am hoping it's because it doesn't knock in other gears.

RN
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Old 07-09-2003, 11:22 PM   #2
awilson529
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11 Mazda

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If it makes the same noise that another STI makes, then its probably detonation

Sorry,
Adam
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Old 07-10-2003, 09:10 AM   #3
sethtasy
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Chapter/Region: MWSOC
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2004 STi
Black w/Silver

Default

If the sound you hear is a faint and rapid "tap-tap-tap-tap-tap" I think it is just the operation of the boost control solenoid. From the research I have done, the nasioc members I talked to, and just listening to the engine, I think this is the case.

I have also got my car to knock (on hot 90+ degree days with high humidity under heavy throttle) and it is quite loud, very "pingy". (93 gas btw)

Other people have described the solenoid sound as "a muffled machine gun" it also sounds to me like someone lightly and quickly drumming on a mostly full coffee can.
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Old 07-11-2003, 06:51 PM   #4
renichms
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2004 Impreza WRX STi
WR Blue

Default

Quote:
Originally posted by sethtasy
If the sound you hear is a faint and rapid "tap-tap-tap-tap-tap" I think it is just the operation of the boost control solenoid. From the research I have done, the nasioc members I talked to, and just listening to the engine, I think this is the case.

I have also got my car to knock (on hot 90+ degree days with high humidity under heavy throttle) and it is quite loud, very "pingy". (93 gas btw)

Other people have described the solenoid sound as "a muffled machine gun" it also sounds to me like someone lightly and quickly drumming on a mostly full coffee can.
It is now a very loud, very obvious sound in 2nd-6th gear. I'm going to look for ways to fix it (colder plugs? automate IC sprayer and have larger tank? somehow more fuel into chamber?).

RN
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Old 07-20-2003, 11:57 PM   #5
Zeta
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Location: Colorado
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MY04 WRX STi
Black/Silver

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Quote:
If the sound you hear is a faint and rapid "tap-tap-tap-tap-tap" I think it is just the operation of the boost control solenoid. From the research I have done, the nasioc members I talked to, and just listening to the engine, I think this is the case.
I have also been getting a noise usually beginning between 3800 and 4500 RPM that sounds like the above. It only happens while shifting into the next gear (usually 3rd or 4th) and while I let out the clutch/apply gas. The sound does not always happen and sounds like an automatic BB gun firing against metal tubing. So someone can confirm it is the solenoid then? I've been worried it was detonation since I so not know (and cant hear) what it sounds like from inside the cabin.

Does pre-ignition sound the same as detonation, or the WRX wav file I listened to? I've been looking for a site that has different sounds of engines and their diagnosis.
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Old 07-21-2003, 12:05 PM   #6
renichms
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2004 Impreza WRX STi
WR Blue

Default

Mine must have adjusted...no noises from mine for a while now.

RN
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Old 07-21-2003, 12:43 PM   #7
HFTuRbo
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Join Date: Mar 2003
Location: Lehigh Valley, PA
Vehicle:
04 WRX STi
Black w/gunmetal

Thumbs up

There is a reported "fix" in the works at another thread. If you are hearing the noise take it to the dealer, report the problem, and have them confirm it.
I'm not going to attempt to "try" to make it detonate/ping. Darn if I can hear it doing anything but pulling. With 94 octane in the tank and no WOT runs just yet it may be a condition with certain production runs, but according to the "fix" thread it is definately an ECU issue. Since it is the ECU, we all have the same ones. The only other difference reported has been the issue of the octane in the tank.
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