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Old 02-24-2017, 09:23 PM   #1
theleveler2600
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Member#: 417541
Join Date: Apr 2015
Default Single Click or "TSST" sound under WOT - UPDATE

So my 05 with a built 2.14 stroker sometimes makes a "TSST" sound under WOT and full boost between 4500 and 6000 RPMs. Looking for any advice, particularly if it may be detonation. Here's some characteristics of the noise:

-from the driver seat, it sounds like an electrical arc/spark that can be heard over the engine (I'm on the stock STI catback, so it's easy to hear noises)

-only happens once per pull when it does

-doesn't always happen, though it seems most likely under max acceleration in 3rd (I've upgraded to the STI 6 speed). I've maybe heard it 50 times in the last year, and comes and goes periodically

-no power loss

-no knock detected in logs or recorded in FLKC in learning view when it happens (and I know my knock sensor works... it's even too sensitive and can even interpret me slapping my shifter around as knock)

-seems to be coming from driver side footwell, down low, though MAYBE more forward in the engine bay

-Adding fuel and pulling a few degrees of timing in my tune has no affect


Anyone have any ideas, and most importantly if this sounds likely to be detonation/pinging?


UPDATE 2/27/2017: I decided to test the assumption that my knock sensor is working well enough to detect actual knock in the rpm/load area where I'm hearing the noise. So I took a risk and added 6 degrees of advance in the WOT areas where I hear the noise. Sure enough, Feedback Knock correction picked up knock and pulled back 4-6 degrees of timing in all 4 pulls I did. There was no affect on the noise (I still heard it twice, no louder or softer). I then flashed it back to the prior safe map. No knock and the noise is yet again unaffected.

Would you all agree that this seems to make detonation being the cause of the noise even more unlikely?


Thanks again!!
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Last edited by theleveler2600; 02-27-2017 at 05:59 PM.
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Old 02-25-2017, 12:08 AM   #2
Adam_W
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Member#: 448203
Join Date: Jun 2016
Location: British Columbia, Canada
Vehicle:
2004 WRX Sedan
Aspen White

Default

What your describing sounds awfully similar to what I have experienced. I have a 2004 WRX and I have heard what I would also describe as a electrical, arc or single sparking noise. My car is stock except for a catback and a boost gauge. It only seems to happen at wide open throttle once it gets into the higher rpm range. I have changed my spark plugs but it didn't seem to help. I haven't experienced power loss. I have been wondering if its jumping spark, a coil pack going bad or maybe a loose spark plug? I'm interested to see what others have to say.
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Old 02-25-2017, 03:12 PM   #3
Charlie-III
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Member#: 30669
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: USA, North NJ, 07456
Vehicle:
1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

Default

OK, may be an odd thought, but, could it be cracked sheetmetal? Since ECU data looks OK (according to the posts), no codes, no performance loss, intermittent occurance, change in tune seems to have no effect.


As to spark jumping, hard enough at times to hear with the hood up and you standing right there.
Loose plug or coil pack, etc. will very likely throw a misfire CEL as well as happen a lot more.

Cracked sheetmetal (firewall, door hinge area, floor pan, etc.) may only make noise when loaded enough to flex it.
May also be heard on certain bumps/road undulations.
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Old 02-25-2017, 04:40 PM   #4
theleveler2600
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Already some interesting ideas! I forgot to say in advance how much I always appreciate the brainstorming dialogues I find here whenever something eludes me with my car! I already have some stuff to investigate thanks to you two and I thank anyone else in advance for offering ideas!

I do feel better that you guys seem to think that a repeating audible detonation would show up in the logs and fine knock control learning. Also, I've listened to several videos of WRXs detonating and I can't find one that sounds the same.. they seem to sound a little scarier, deeper, and oscillating.
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Old 02-27-2017, 05:58 PM   #5
theleveler2600
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Member#: 417541
Join Date: Apr 2015
Default

UPDATE 2/27/2017: I decided to test the assumption that my knock sensor is working well enough to detect actual knock in the rpm/load area where I'm hearing the noise. So I took a risk and added 6 degrees of advance in the WOT areas where I hear the noise. Sure enough, Feedback Knock correction picked up knock and pulled back 4-6 degrees of timing in all 4 pulls. There was no affect on the noise (I still heard it, no louder or softer). I then flashed it back to the prior safe map.

Would you all agree that this seems to make detonation being the cause of the noise even more unlikely?


Thanks again!!
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Old 03-01-2017, 09:37 PM   #6
Zach201
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Have you tried adding another ground wire to your engine?
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Old 03-02-2017, 02:09 PM   #7
theleveler2600
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Quote:
Originally Posted by Zach201 View Post
Have you tried adding another ground wire to your engine?
No actually, but with the age of my car I should probably do that anyway!
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Old 03-07-2017, 05:27 PM   #8
andyfloyd
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Join Date: May 2005
Vehicle:
2002 wrx
silver

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why dont you pull timing insead and see if it goes away? Take 2 deg out and do some WOT runs.

edit : i see you already tried that. Carry on
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