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Old 11-20-2007, 12:33 AM   #1
Fred Fredburger
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Member#: 2539
Join Date: Oct 2000
Location: Snohomish, WA, USA
Default Low RPM/low boost knocking?

Evening all.

Trying to tune some mid-RPM (3250-4500) knock out of my car in the 90-100 load points and ran across some VERY bizarre knocks. Very light throttle (11-12%), very low boost (-6)...

Code:
***91;TSMP***93;***91;RPM***93;***91;PSIG***93;***91;MAF***93;***91;TPS***93;***91;LOD***93;***91;KN***93;***91;SNB***93;***91;SIG***93;***91;IDC%***93;***91;IGN***93;***91;FMVL***93;***91;BMV***93;***91;MMV***93;***91;WBO2***93;
985.47 1803  -9.8 1.9    8    0   0  14.3 34.2   4.8 ECU   +1.0 ECU  1.9  19.87
985.67 1840  -9.1 1.9    8    0   0  14.0 35.3   4.5 ECU   +1.0 ECU  1.8  14.42
985.87 1839  -8.9 1.9    8    0   0  14.5 35.0   4.8 ECU   +1.0 ECU  1.9  14.63
986.07 1843  -8.7 1.9   10    0   0  14.5 34.9   5.0 ECU   +1.0 ECU  1.9  15.02
986.27 1835  -8.5 1.9   10    0   0  14.3 35.1   5.2 ECU   +1.1 ECU  2.0  14.61
986.47 1842  -7.9 2.0   11    0   0  14.3 35.4   7.2 ECU   +1.0 ECU  2.1  14.05
986.67 1841  -6.3 2.0   11    0   1  13.6 37.4   6.8 ECU   +1.0 ECU  2.1  13.63
986.87 1838  -5.9 2.1   11    0   0  14.0 37.6   7.0 ECU   +1.0 ECU  2.1  13.53
987.34 1868  -5.7 2.1   12    0   2  14.3 35.6   6.9 ECU   +1.0 ECU  2.1  14.38
Code:
***91;TSMP***93;***91;RPM***93;***91;PSIG***93;***91;MAF***93;***91;TPS***93;***91;LOD***93;***91;KN***93;***91;SNB***93;***91;SIG***93;***91;IDC%***93;***91;IGN***93;***91;FMVL***93;***91;BMV***93;***91;MMV***93;***91;WBO2***93;
995.63 1872  -3.0 2.3   20    0   0  14.3 30.9   9.6 ECU   +1.0 155  2.2  14.28
995.84 1885  -2.8 2.3   20    0   0  14.3 26.9   9.4 ECU   +1.0 155  2.3  14.16
996.04 1871  -2.8 2.3   20    0   0  14.3 26.2   9.4 ECU   +1.0 155  2.2  14.11
996.23 1866  -2.6 2.4   20    0   0  14.3 26.8   9.3 ECU   +1.0 155  2.3  14.15
996.43 1888  -2.6 2.3   20    0   0  14.3 25.9   9.7 ECU   +1.0 155  2.3  14.18
996.64 1888  -2.4 2.3   18    0   0  14.3 25.6   9.6 ECU   +1.0 ECU  2.3  14.16
996.84 1910  -2.8 2.3   16    0   0  14.3 26.0   9.5 ECU   +1.0 ECU  2.3  14.19
997.03 1899  -3.6 2.1   12    0   1  14.3 27.7   8.9 ECU   +1.0 ECU  2.2  14.26
997.23 1941  -4.7 2.1   12    0   1  14.5 31.3   7.8 ECU   +1.0 ECU  2.1  14.42
Code:
***91;TSMP***93;***91;RPM***93;***91;PSIG***93;***91;MAF***93;***91;TPS***93;***91;LOD***93;***91;KN***93;***91;SNB***93;***91;SIG***93;***91;IDC%***93;***91;IGN***93;***91;FMVL***93;***91;BMV***93;***91;MMV***93;***91;WBO2***93;
998.23 1948  -5.3 2.1   12    0   0  14.3 32.6   7.8 ECU   +1.0 ECU  2.2  14.44
998.43 1956  -5.3 2.1   12    0   0  14.3 30.6   7.8 ECU   +1.0 ECU  2.2  14.41
998.63 1968  -5.3 2.1   12    0   0  14.5 30.7   7.8 ECU   +1.1 ECU  2.1  14.33
998.83 1979  -5.3 2.2   13    0   0  14.3 30.8   7.8 ECU   +1.0 ECU  2.2  14.30
999.02 1974  -5.5 2.1   12    0   0  14.3 30.8   7.6 ECU   +1.0 ECU  2.2  14.36
999.22 1991  -5.5 2.1   12    0   0  14.5 30.9   7.5 ECU   +1.0 ECU  2.1  14.50
999.42 1997  -5.5 2.1   12    0   0  14.5 30.8   7.8 ECU   +1.0 ECU  2.2  14.56
999.62 2006  -5.3 2.2   13    0   1  14.3 28.9   7.8 ECU   +1.0 ECU  2.2  14.44
999.84 1988  -5.5 2.1   12    0   1  14.3 28.9   7.6 ECU   +1.0 ECU  2.2  14.27
Code:
***91;TSMP***93;***91;RPM***93;***91;PSIG***93;***91;MAF***93;***91;TPS***93;***91;LOD***93;***91;KN***93;***91;SNB***93;***91;SIG***93;***91;IDC%***93;***91;IGN***93;***91;FMVL***93;***91;BMV***93;***91;MMV***93;***91;WBO2***93;
208.27 2766  -1.6 2.8   23    0   1  14.3 34.6  16.1 ECU   +1.4 170  2.8  13.94
208.48 2794  -2.0 2.8   23    0   1  14.0 34.7  16.3 ECU   +1.4 170  2.8  14.04
208.68 2866  -1.8 2.8   23    0   0  14.3 35.1  16.4 ECU   +1.4 170  2.7  14.10
208.87 2888  -2.0 2.8   23    0   0  14.3 34.8  17.1 ECU   +1.4 165  2.8  14.08
209.06 2908  -1.8 2.8   23    0   1  14.3 35.2  17.4 ECU   +1.4 165  2.8  14.05
209.27 2952  -1.8 2.8   23    0   1  14.3 36.0  17.2 ECU   +1.4 170  2.8  14.08
209.47 3005  -2.0 2.8   23    0   1  14.3 35.9  17.5 ECU   +1.4 165  2.8  14.09
209.66 3016  -2.0 2.8   23    0   1  14.3 36.4  17.5 ECU   +1.4 165  2.8  14.07
209.87 3058  -2.2 2.8   22    0   1  14.3 36.6  17.7 ECU   +1.4 160  2.8  14.07
What gives?

First time I've ever seen anything like this. I hadn't driven the car for about a week before yesterday. I threw on my snow tires, warmed it up, and drove about 10 miles yesterday. I drove it to work this morning (about 10 miles), after work I went to the neighboring town about 20 miles away, shut it off for about 35 minutes and then the problem started.

I'm staying below the crossover so I think the UTEC's just reporting the knocks. I had it tuned in April and, aside from my mid-range knock I haven't really had any issues with the tune.

Any ideas?

Thanks!

FFb
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Old 11-20-2007, 03:56 AM   #2
WRX-Blue-Mica
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Default

It is quite strange because your car was knocking when the STock ECU still in control according to UTEC. Your boost still negative ... r u sure nothing making any noise under the hood?

Maybe for the temporary solution you can tune the 0% column timing (reduce the timing).

just my 2 cnt
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Old 11-20-2007, 06:43 AM   #3
hotrod
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Default

I doubt that is real knock, probably some other cause like a loose heat shield etc.

You can't have detonation when the engine is not under load, unless the tune is totally in the wrong time zone so baddly it would instantly kill the engine under boost.

Larry
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Old 11-20-2007, 07:24 AM   #4
RP31
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+1 for Larry's idea. I've been fighting the same problem, and have yet to discover the cause. I have noticed that my engine seems to do this more when it's a bit low on oil.
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Old 11-20-2007, 09:15 AM   #5
Fred Fredburger
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Location: Snohomish, WA, USA
Default

Quote:
Originally Posted by WRX-Blue-Mica View Post
Your boost still negative ... r u sure nothing making any noise under the hood?
Noise under the hood = something external rattling () or Noise under the hood = bad noise coming from inside the engine ()?

Quote:
Originally Posted by hotrod View Post
I doubt that is real knock, probably some other cause like a loose heat shield etc.
I assume it'd have to be close (i.e. connected to the motor) like the exhaust manifold heat shield? When I was at the track in April I had a heat shield above the tranny rattling but I couldn't put my finger on it. I would think the turbo heat shield would be too far away, eh?

Quote:
Originally Posted by RP31 View Post
+1 for Larry's idea. I've been fighting the same problem, and have yet to discover the cause. I have noticed that my engine seems to do this more when it's a bit low on oil.
Thankfully I don't think that's it. I just filled up last night (after all this was going on) and I was about a quarter of a quart low. Heck, even my wife's Corolla didn't knock when it was 3 quarts low. That was before I had her trained to check things like that.

Anyone have any idea what things to check under the hood?

I'll need to drive with the window down when pulling away from stop signs/lights to tell if I can hear it at all. If I could hear it all the time (even if it's only causing knock some of the time) that'd sure be helpful for tracking it down. Heck, I don't have anything else to listen to while I'm driving (friggin' Infinity crap ).
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Old 11-20-2007, 09:50 AM   #6
hotrod
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Quote:
Anyone have any idea what things to check under the hood?

I'll need to drive with the window down when pulling away from stop signs/lights to tell if I can hear it at all.
Yes --- everything --- just start at the top or the front or where ever and start shaking thinks or tapping them with a hammer handle to see if you get a solid clunk or a secondary sound from them rattlinging or hitting something else. Even if you do not find it, you have still determined a large number of things that probably are not to blame.

Try finding a location like a narrow alley where you can drive with your window down right next to a concrete or brick wall. It makes it very easy to hear noises that are impossible to hear effectively inside the car.

Larry
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Old 11-20-2007, 11:42 AM   #7
Fred Fredburger
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Default

Quote:
Originally Posted by hotrod View Post
Yes --- everything

Quote:
Originally Posted by hotrod View Post
just start at the top or the front or where ever and start shaking thinks or tapping them with a hammer handle to see if you get a solid clunk or a secondary sound from them rattlinging or hitting something else. Even if you do not find it, you have still determined a large number of things that probably are not to blame.

Try finding a location like a narrow alley where you can drive with your window down right next to a concrete or brick wall. It makes it very easy to hear noises that are impossible to hear effectively inside the car.
I'll give that a shot this long holiday weekend and see if I can figure anything out.

Thanks for all the help, guys! I'll report back...
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Old 11-22-2007, 10:53 AM   #8
Fred Fredburger
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Last night when I was running some errands I noticed the knocking at various RPMs, still with no positive boost. It got me thinking, I checked my plugs about 3 weeks ago and a 12mm socket fell down on the passenger side of the engine compartment. It went down near the coils, and after spending about 30 minutes looking for it (rock guard, exhaust shields, etc) I gave up. I had summarily forgotten about it, but I thought about it again yesterday as a good candidate for causing the knock. Hopefully tomorrow I'll have some time to crawl under the car and see if I can track that down.
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Old 11-22-2007, 10:59 AM   #9
RP31
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^^^
If that works, I will blame mine on one or both of the 8mm sockets that my engine bay ate during a turbo swap.
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