False knock
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Teching In
Joined: Jul 2018
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False knock I have a 94 z28 Camaro m6. The motor was bored 30 over 355 and that’s about all I know.heads look new.a older guy had the car rebuilt and forgot what he had done to it,he spent 5k on the motor.i got it tuned and the tuner keeps telling me the motor has knocks all over.i don’t hear any.it runs good.he says it only happens at wot.i don’t know the deg of timing when it’s happining. I do have a data log if someone would like to look.i do have a little vibration when I rev the motor.dont know where it’s coming from.i was told to get a lt4 module then a sensor.do I need both or what do I need to do?this is about over my pay grade lol.
easiest test to do is jack up the car and start banging on the exhaust with a rubber mallet, you will hear sound change when you encounter an area where the exhaust is touching the frame/suspension.
your tuner should have been able to verify if it was false knock by either having you increase the octane of the fuel being used or reducing ignition timing to see if the knock goes away.
your tuner should have been able to verify if it was false knock by either having you increase the octane of the fuel being used or reducing ignition timing to see if the knock goes away.
As far as the LT4 knock sensor is concerned there is no such thing, it's the same as the LT1 knock sensor. The LT4 knock module, which are becoming increasingly expensive and hard to source, will help with some false knock but will only be a bandaid when there is a large amount of noise causing false knock.
If it's false knock the only way to tune it out is to reduce the amount of timing retard the pcm is allowed to pull. For some people this is the only option like those with solid rollers or gear drives where the mechanical noise is impossible to overcome.
The problem with this is if there is real knock at some point the pcm will not be able to pull timing. I would recommend trying to remove the source of the false knock to the best of your ability before you try to "tune it out".
The problem with this is if there is real knock at some point the pcm will not be able to pull timing. I would recommend trying to remove the source of the false knock to the best of your ability before you try to "tune it out".
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Joined: Apr 2008
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[QUOTE=Jason28;20085772]I have a 94 z28 Camaro m6. The motor was bored 30 over 355
i do have a little vibration when I rev the motor. dont know where it’s coming from.
….you need to find out what is causing this "vibration"....because your PCM certainly see's it as "knock"
It could be as simple as exhaust, or other engine/transmission component, hitting something as motor is reved
...or it could be a "engine balance" issue when the motor was rebuilt....like it is now a internal balance motor (VERY common for rebuilds) still using a "external" balance flywheel or flexplate
you need to find out the "why" there is a vibration when reving before dumbing down (read don't ever do this) the PCM to not see knock be it false or real as dumbing the PCM down and knock is real = BOOM
i do have a little vibration when I rev the motor. dont know where it’s coming from.
….you need to find out what is causing this "vibration"....because your PCM certainly see's it as "knock"
It could be as simple as exhaust, or other engine/transmission component, hitting something as motor is reved
...or it could be a "engine balance" issue when the motor was rebuilt....like it is now a internal balance motor (VERY common for rebuilds) still using a "external" balance flywheel or flexplate
you need to find out the "why" there is a vibration when reving before dumbing down (read don't ever do this) the PCM to not see knock be it false or real as dumbing the PCM down and knock is real = BOOM
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