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Old 12-12-2007, 12:12 AM   #1
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default How Do You Know if Knock is Real (and how do you kill it?)

OK, so the ECU thinks my car is knocking like crazy in mid-rpm, mid-throttle situations. On the surface, I'm inclined to believe it, because I do at times hear a sound under those conditions that sounds like the classical description of knock. I've been data logging the car, and have found that the car is making HUGE pulls to timing under part-throttle, mid-rpm conditions. It's yanking as much as 4.55* for up to 10 seconds. This seems to correlate well with the sound I'm hearing. However, due to the way things happen, I have no way for telling if the sound I'm hearing happens at the same time the ECU is sensing knock. I've tried some things try to get rid of the knock like better gas and new plugs. The knock hasn't gone away, and if anything, it's worse.

So I'm beginning to wonder if the ECU is hearing something else. Is there any way to determine if the knock the ECU is sensing is actually real knock or just some other noise it's picking up on and incorrectly labeling as knock?

If it is real knock, what else can I do to make it go away?

BTW, this is an 05 2.5RS with a totally stock engine and stock tune. It has 55k miles and all maintenance is current.

For those of you used to reading logs, here's a snippet of a log showing the knock.

Code:
										
Time	RPM	Throt%	g/rev	AFR	AFC	AFL	CL/OL	FBKC	FLKC	IAM
113125	2002	16.47	0.60	14.59	2.34	3.12	8	0.00	0	0.875
113469	2010	16.86	0.60	14.59	1.56	3.12	8	0.00	0	0.875
113828	2014	16.86	0.59	14.70	2.34	3.12	8	0.00	0	0.875
114219	2024	16.86	0.60	14.70	2.34	3.12	8	0.00	0	0.875
114563	2039	16.86	0.59	14.59	2.34	3.12	8	-1.05	0	0.875
114907	2042	16.86	0.60	14.59	2.34	3.12	8	-1.05	0	0.875
115266	2036	17.65	0.64	14.24	0.00	3.12	8	-1.05	0	0.875
115610	2053	17.65	0.65	14.59	0.00	3.12	8	-0.70	0	0.875
115953	2041	17.65	0.65	14.59	0.00	3.12	8	-1.75	0	0.875
116297	2044	17.65	0.65	14.59	0.00	3.12	8	-2.80	0	0.875
116657	2046	17.65	0.65	14.59	-0.78	3.12	8	-3.85	0	0.875
117000	2050	18.04	0.65	14.59	-0.78	3.12	8	-3.85	0	0.875
117360	2060	17.65	0.65	14.59	-0.78	3.12	8	-3.85	0	0.875
117703	2062	17.65	0.65	14.70	-0.78	3.12	8	-3.50	0	0.875
118047	2070	17.65	0.65	14.70	-0.78	3.12	8	-3.50	0	0.875
118407	2077	17.65	0.65	14.59	-0.78	3.12	8	-3.50	0	0.875
118750	2078	18.04	0.65	14.59	-1.56	3.12	8	-4.20	0	0.875
119110	2081	18.04	0.65	14.70	-0.78	3.12	8	-4.20	0	0.875
119453	2090	18.04	0.65	14.59	-0.78	3.12	8	-4.20	0	0.875
119782	2100	18.04	0.64	14.70	-0.78	3.12	8	-3.85	0	0.875
120141	2110	18.04	0.65	14.59	-0.78	3.12	8	-3.85	0	0.875
120485	2114	18.04	0.65	14.70	-0.78	3.12	8	-3.85	0	0.875
120844	2116	18.43	0.66	14.59	-0.78	3.12	8	-3.50	0	0.875
121188	2136	18.43	0.66	14.59	-0.78	3.12	8	-4.55	0	0.875
121547	2133	18.43	0.66	14.59	-0.78	3.12	8	-4.55	0	0.875
121891	2146	18.43	0.66	14.70	-0.78	3.12	8	-4.55	0	0.875
122250	2154	18.43	0.66	14.70	-0.78	3.12	8	-4.20	0	0.875
122610	2156	18.43	0.66	14.59	-0.78	3.12	8	-4.20	0	0.875
122953	2168	18.43	0.65	14.70	0.00	3.12	8	-4.20	0	0.875
123297	2172	18.43	0.65	14.70	0.00	3.12	8	-3.85	0	0.875
123657	2172	18.43	0.66	14.70	0.78	3.12	8	-3.85	0	0.875
124063	2180	18.43	0.66	14.59	0.00	3.12	8	-3.85	0	0.875
124407	2192	18.43	0.66	14.59	0.00	3.12	8	-3.50	0	0.875
124750	2198	18.43	0.65	14.70	0.00	3.12	8	-3.50	0	0.875
125094	2188	16.86	0.61	14.59	0.00	3.12	8	-3.15	0	0.875
125438	2201	16.08	0.55	14.59	0.00	3.12	8	0.00	0	0.875
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Old 12-12-2007, 12:11 PM   #2
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Dumb question: The 2.5RS in '05 was still naturally aspirated, was it not?

You tried premium fuel (91, 92, 93 octane) and that didn't affect it? I know that many, many of the naturally aspirated cars I've had (most or all over the last ~15 years) would knock lightly under the conditions you're seeing, and one of my farm pickups would knock so hard I truly thought it would grenade some of the time. Nothing helped, not even the highest octane fuel I could buy spiked with octane booster. Never had any troubles, either. Not knowing any better, I wouldn't be at all concerned about 4 degrees of timing retard under these conditions.

FWIW
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Old 12-12-2007, 01:20 PM   #3
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

I did try higher octane fuel. I thought at first it had solved the problem, but no.
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Old 12-12-2007, 01:42 PM   #4
Undepelo
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Member#: 34960
Join Date: Apr 2003
Chapter/Region: MAIC
Location: MD
Vehicle:
What would baby
Jesus say of OT?

Default

who's there?... sorry I got out of OT...nevermind.
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Old 12-16-2007, 11:45 PM   #5
yarrgh
Scooby Specialist
 
Member#: 80465
Join Date: Jan 2005
Chapter/Region: RMIC
Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

Default

you can ask in the NA forums. some people have used teflon tape on the bolt connecting the knock sensor to the block, or even some sort of non-melting spacer between the sensor and the block. this kinda "fools" the sensor into not picking up background noise. although if a real knock occurs, i'm not sure it if would deaden the noise too much.
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