Sources of knock (false?) - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 09-12-2005, 11:17 PM   #11
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After what I found on mine, I'd say exhaust restriction (OEM welds) and exhaust manifold cracks are the two most likely culprits.
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Old 09-12-2005, 11:19 PM   #12
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If I take out the knock sensor, coolant will soon follow, correct? If I take it out and clean the threads, what should I reinstall it with?

Can faulty lifters cause it? I have quite a bit of lifter clatter.
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Old 09-12-2005, 11:21 PM   #13
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could the trans cause some false knock when shifting??? when i scanned my car...i had some knock, and i think one of the trans mounts are goin
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Old 09-12-2005, 11:23 PM   #14
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Really it comes down to this: If it makes noise, it can cause KR.

I know, it'* a pain, but that'* really all the knock sensor looks for...noise at a specific frequency.
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Old 09-13-2005, 12:32 AM   #15
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For your leaking oil you can get a small bottle of stop leak for oil and add it in. I did this when mine was leaking it had over half of the oil gone when i added 1 bottle and toped the rest of it off with oil. Since then i have drove over 6k and i have not lost a drop since.
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Old 09-13-2005, 12:35 AM   #16
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Stop leak (mechanic in a can) is a last-ditch resort and won't do anything to stop the typical leak where the heads, LIM, and block meet in the 4 corners. This is a non-pressure 'splash' leak typical on high mileage motors.

Stop leak is really (in the long run) not a good idea. Proper repair of the leak is paramount.
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Old 09-13-2005, 12:48 AM   #17
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Default Re: Sources of false knock

Quote:
Originally Posted by jwikoff99
However, going 70 mph on the highway, floor it so it shifts to second, I saw 17 DEGREES for a moment, dropped to 11 then dropped off.
Don't assume it'* false knock. By all means check around for potential causes but the situation you describe is more common than you might think.

Flash KR like above can, and often is, caused by lean mixtures.

If your LTFTs are such that the PCM pulls fuel in Open Loop mode it may indicate you need some MAF tuning. Also, you'll often find a lot more AE (acceleration enrichment) is needed to quench that knock. I've seen cars need triple the OEM setting of AE (like an accelerator pump for you carb guys) to get past this hump.

Cheers,
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Old 09-13-2005, 04:31 PM   #18
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I would seriously consider that missing oil every change.
Did you finish those heads or install them yet?
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Old 09-13-2005, 04:57 PM   #19
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Not yet, waiting on springs, retainers, keepers, and pushrods from SOP.
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Old 09-13-2005, 04:58 PM   #20
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I guess I need to record and post some more scantool data.
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