C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Knock sensor modification?

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Old May 2, 2017 | 12:56 PM
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Default Knock sensor modification?

A GM tech told me about using brass hardware to move out the knock sensor from the block to correct problems with false knock. I know I've seen this discussed but I was curious if anyone has seen this first hand and if it actually worked?? It sounded a little "bubba" but once I heard it was a fix used by dealers back then it made me curious.
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Old May 2, 2017 | 01:06 PM
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Scroll to post 11. The author is a reputable Corvette authority.

https://www.corvetteforum.com/forums...deadening.html
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Old May 2, 2017 | 02:01 PM
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Originally Posted by AJT84
A GM tech told me about using brass hardware to move out the knock sensor from the block to correct problems with false knock. I know I've seen this discussed but I was curious if anyone has seen this first hand and if it actually worked?? It sounded a little "bubba" but once I heard it was a fix used by dealers back then it made me curious.
I know this goes against the grain, and it will get the "ire" of 99.9% of the forum members. I have experience and yes it worked. I went with a 227/234; .574;110LSA full roller rocker, LT headers in my 1994 LT1. I went the correct route, new 1.6 roller rockers, hardened pushrods, valve springs, new valves, heads done by Lloyd Elliot, etc. It sounds a little like a Singer sewing machine. And yes, valve train is properly adjusted. Here in Florida we have 93 octane and that's all I run. Knock was off the board. I devised my own knock hardware to remove sensors out from block and not give codes. False knock gone. Everyone seems to say the engine will implode, kaboom, etc. Maybe I'm one very lucky guy, but in a year, no problems. I go to car shows and talk to a lot of guys. Everyone seems to have a great fear of messing with factory KS. No one can give one actual case of an engine going "kaboom" just heresay. I don't advocate this to anyone, this is just my personal experience and I'll be the one buying a new crate engine and hearing a lot of "I told you so" if my LT1 disintegrtates itself. O.K. bring on the wrath
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Old May 2, 2017 | 02:17 PM
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Originally Posted by seabright
Scroll to post 11. The author is a reputable Corvette authority.

https://www.corvetteforum.com/forums...deadening.html
He may be a reputable authority, but what he says doesn't make any sense.

Originally Posted by Hib Halverson
There is *no* safe solution to the problem of false knock stemming from an increase in valve train noise broght on by a camshaft that is more aggressive than production cams *other than* using gasoline of higher octane than can be typically found from most sources.
There is no way that higher octane gas will eliminate false knock from valvetrain noise.

Last edited by dorri732; May 2, 2017 at 02:18 PM. Reason: spelling
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Old May 2, 2017 | 07:47 PM
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Not sure about moving the ks away from the block, but I believe that the knock sensors are specific to each engine, so if you might have just picked up one off the shelf, or from a parts guy who didn't need to look it up, you might have the wrong one, and that might be an issue. Just cause it fits doesn't mean it's right. My $.02.
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Old May 2, 2017 | 09:02 PM
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I'm using an LT4 knock module in my heads/cam/headers 94 LT1, and no false knock.

For those that don't know the LT4 knock module can only be used in 94-96's.
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Old May 2, 2017 | 09:11 PM
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I was told by a corvette tech, when I did a coolant flush and got LT4 knock sensors, that I should use the LT1 sensors sense that is what belongs in the car,(94 LT1) he said LT4 are less tolerant to knock, so I sent the LT4 sensors back and got the right LT1s. So I would say that LT4s are less sesitive to knock than LT1s.
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Old May 2, 2017 | 09:16 PM
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LT4 (OBD II) knock sensors and LT4 knock module are two different components.

Last edited by STL94LT1; May 2, 2017 at 09:18 PM.
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Old May 2, 2017 | 10:12 PM
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My reason for the post was mostly to flush out whether it was a myth or not. Apparently it does reduce the sensitivity of the sensor. I was wondering if someone tried it with no or little affect or, as posted above, someone who did it and it worked for them. I'm not trying to confirm it for my use or debate the right or wrong. Obviously if you're engine is knocking then bypassing the sensor is not correct. Do guys extend the sensor straight out with a coupling or 90 degree fitting? Or whatever works?

Thanks for the replies by the way. I find things like this interesting when guys have first hand experience.
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Old May 2, 2017 | 10:19 PM
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Originally Posted by A Peter C4
I was told by a corvette tech, when I did a coolant flush and got LT4 knock sensors, that I should use the LT1 sensors sense (sic) that is what belongs in the car,(94 LT1) he said LT4 are less tolerant to knock, so I sent the LT4 sensors back and got the right LT1s. So I would say that LT4s are less sesitive (sic) to knock than LT1s.
LT1 and LT4 knock sensors are the exact same part. It's the knock module (in the ECM) that is different.
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Old May 2, 2017 | 10:25 PM
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Not so different part #s
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Old May 3, 2017 | 07:45 AM
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Originally Posted by A Peter C4
Not so different part #s
According to the GMpartsdirect website, there is only one part number for knock sensors for the 1996 Corvettes.

The knock module is definitely different between LT1 and LT4 cars.
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Old May 3, 2017 | 10:07 AM
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Originally Posted by dorri732
According to the GMpartsdirect website, there is only one part number for knock sensors for the 1996 Corvettes.
This is true. But, the 1996 (OBDII) knock sensors cannot be used with pre 1996 LT1's.
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Old May 3, 2017 | 01:37 PM
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Years ago to reduce false knock, I wrapped the knock sensor with layers of teflon tape and tightened them just tight enough.
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Old May 3, 2017 | 06:05 PM
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Originally Posted by AJT84
A GM tech told me about using brass hardware to move out the knock sensor from the block to correct problems with false knock. I know I've seen this discussed but I was curious if anyone has seen this first hand and if it actually worked?? It sounded a little "bubba" but once I heard it was a fix used by dealers back then it made me curious.
What year car is yours?
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Old May 3, 2017 | 09:52 PM
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96 and earlier LT1 #KS2,95 and earlier LT4 #KS3 Standard Motor Products part #'s
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