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09-01-2010
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#1 |
 
Join Date: Jun 2004
Location: Texas
Posts: 2,418
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If a knock sensor goes bad ................
Will or can there be an audible knocking sound (like a bad rod bearing) that can be easily heard? Just curious, thanks
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09-01-2010
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#2 |
 
Join Date: Aug 2008
Location: Houston, TX
Posts: 2,314
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Re: If a knock sensor goes bad ................
Do you hear a knocking sound?
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09-01-2010
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#3 | |
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Join Date: Jun 2004
Location: Texas
Posts: 2,418
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Re: If a knock sensor goes bad ................
Quote:
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09-01-2010
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#4 | |
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Join Date: Aug 2008
Location: Houston, TX
Posts: 2,314
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Re: If a knock sensor goes bad ................
Quote:
Last edited by rhipsher; 09-01-2010 at 07:14 PM. |
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09-01-2010
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#5 |
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Join Date: May 2009
Location: S Nevada
Posts: 351
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Re: If a knock sensor goes bad ................
On my 92 a complete main bearing set was installed (motor was pulled) Still had a knock not a tap a deep lower knock. Crank or connecting rod culprit.
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09-01-2010
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#6 |
Join Date: May 2005
Location: Leesburg, VA
Posts: 2,704
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Re: If a knock sensor goes bad ................
Just a peanut gallery two cents. But I believe the knock sensor is tuned somewhat specifically (via a crystal with a certain resonant frequency? Or at least that's what I thought) to the tune of a ringing block. I don't know if clunky noises will necessarily affect it.
I do believe though that the ECM will advance the timing to a point where it expects knock, as a self-test of the sensor. If it didn't see a knock signal, it will set code 43. It won't run the test if it sees knock signals before it gets around to running the test. So if your knock sensor is MIA, it should throw a code. Also, there's practically no way you should have knock at idle or low throttle. The cylinder pressures are really low. So if you hear it all the time, I wouldn't think it is spark knock. |
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09-01-2010
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#7 |
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Join Date: Jun 2004
Location: Texas
Posts: 2,418
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Re: If a knock sensor goes bad ................
Thanks for the thoughts guys. Anything else that might cause a knocking sound besides rods and crank in an LT5?
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09-02-2010
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#8 |
Join Date: Dec 2003
Location: Arcadia, OK
Posts: 3,392
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Re: If a knock sensor goes bad ................
Dual mass flywheel commonly sounds like a rod knock at idle when it gets "worn". if you advance the rpm to 1,000~1250, hold it steady & the knock goes away, it's probably the flywheel.
If the knock is not present at the higher rpm, you may have a weak miss. You might consider new plugs or gapping closer at about ).040"~0.042". Demps favors the closer gap on the later cars, I'm on the rail whether that's a good move. The real problem is probably the Dunn heads. I have a real nice pair of 90 Birmal heads that I would trade with you, being the good ol boy I am! You know how we Okies take care of our neighbors to the south.
__________________
Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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09-02-2010
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#9 |
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Join Date: Jun 2004
Location: Texas
Posts: 2,418
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Re: If a knock sensor goes bad ................
Jerry,
I bet you do have a set of Birmals for the far superior DUNNs but the knock problem is NOT my car. My 95 purrs like a kitten  I have received news on the possible cause of the knock and will let the owner speak after checking it out.Good to know my friends to the North are so thoughtful 
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09-02-2010
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#10 |
Join Date: Dec 2007
Location: Fremont, CA
Posts: 3,087
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Re: If a knock sensor goes bad ................
A dead cylinder will cause the knock from the flywheel.I got this with dead injectors,dead coil.Carter,hows my TB plate coming along?
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