Knock Retard Normal???
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Knock Retard Normal???
I was reading in my How to Tune n Mod Chevy FI,
Quote: Because a slight amount fo ping is to be considered normal on applications equipped with ESC system, a reading of four or so should not be interpreted as a problem. pg. 103.
I have also read some where that the ECM will advance the timing untill it see's a knock.
My self and others have be chasing this perceived problem. I'm seeing upto 8* (peak) of knock retard above 4000rpm at WOT. I have tried octane boost and a retorque of the sensors to 12-14ft lb nojoy.
Is this normal??
I'm sure the CF knows :yesnod:
:seeya
Quote: Because a slight amount fo ping is to be considered normal on applications equipped with ESC system, a reading of four or so should not be interpreted as a problem. pg. 103.
I have also read some where that the ECM will advance the timing untill it see's a knock.
My self and others have be chasing this perceived problem. I'm seeing upto 8* (peak) of knock retard above 4000rpm at WOT. I have tried octane boost and a retorque of the sensors to 12-14ft lb nojoy.
Is this normal??
I'm sure the CF knows :yesnod:
:seeya
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Knock Retard Normal??? (C4Crazy787)
The early L98s used the ESC module but not later ones; I don't think the LT1 uses it.
I was getting similar knock retard and Gordon Killebrew gave me the P/N of an "upgraded" ESC module. Installing it cured my false knock issues even with base timing at 8deg BTDC.
In your case you might try backing off base timing to see if knock retard is reduced. If not look for some cause of false knock; I believe you can also install the LT4 knock sensor to reduce sensitivity.
I was getting similar knock retard and Gordon Killebrew gave me the P/N of an "upgraded" ESC module. Installing it cured my false knock issues even with base timing at 8deg BTDC.
In your case you might try backing off base timing to see if knock retard is reduced. If not look for some cause of false knock; I believe you can also install the LT4 knock sensor to reduce sensitivity.
Burning Brakes
Joined: Jun 2003
Posts: 949
Likes: 0
From: smithtown ny
Re: Knock Retard Normal??? (C4Crazy787)
okay well it's good to hear that some is normal i'm getting no more than 5 degrees of retard but why is it happening at 3800 rpms you can feel the performance loss and it is supposed to make peak power at 4500-4800 rpm i'm dying out at 3800 thats were it starts????????????????
Burning Brakes
Joined: Jun 2003
Posts: 949
Likes: 0
From: smithtown ny
Re: Knock Retard Normal??? (C4Crazy787)
i found this Step 5----Same as above, except disconnected Knock Sensor due to false knock pick-up.
Step 5 results----1.70 60 foot, 12.42 @ 109 mph (Another victory, and again, my very 1st pass doing this I broke my previous best mph and et.... it was obvious, the knock sensor was reporting false knock to the ecm, perhaps caused by the harmonics of the headers or valvetrain chatter of the hyd roller cam. When the ecm reads falsely that the knock sensor is picking up false knock, it retards the timing anywhere from 2-8 degrees at wot... thus damaging performance when the retard was not necessary in reality. Everybody should think about trying this quick and simple test. {i have tpis headers with stage 8 bolts they have metal locking tabs that rattle thats one problem} 91 vette
Step 5 results----1.70 60 foot, 12.42 @ 109 mph (Another victory, and again, my very 1st pass doing this I broke my previous best mph and et.... it was obvious, the knock sensor was reporting false knock to the ecm, perhaps caused by the harmonics of the headers or valvetrain chatter of the hyd roller cam. When the ecm reads falsely that the knock sensor is picking up false knock, it retards the timing anywhere from 2-8 degrees at wot... thus damaging performance when the retard was not necessary in reality. Everybody should think about trying this quick and simple test. {i have tpis headers with stage 8 bolts they have metal locking tabs that rattle thats one problem} 91 vette
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: Knock Retard Normal??? (65Z01)
In your case you might try backing off base timing to see if knock retard is reduced.
If not look for some cause of false knock
I believe you can also install the LT4 knock sensor to reduce sensitivity.
:seeya
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Knock Retard Normal??? (6spd)
If excess timing advance is the issue then reprogramming the chip would work; but if the knock sensor was "turned off" that is trouble waiting to happen.
If not excessive timing advance the problem must be in the sensor or some mechanical issue. You could try desensitizing the sensor and locating the cause of "clang".
If not excessive timing advance the problem must be in the sensor or some mechanical issue. You could try desensitizing the sensor and locating the cause of "clang".
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: Knock Retard Normal??? (6spd)
when my friend was having the same problem as we are he had a custom prom done no more problem so what did they do to the chip???????
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Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: Knock Retard Normal??? (65Z01)
but if the knock sensor was "turned off" that is trouble waiting to happen.
I have suspected I have a bad lifter for a while now. This could be the root of the problem.
[Modified by C4Crazy787, 6:30 PM 1/19/2004]
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: Knock Retard Normal??? (6spd)
LT4 knock sensor/ module will not work on my LT1 or L98
http://forums.corvetteforum.com/zerothread?id=640484
http://forums.corvetteforum.com/zerothread?id=640484
Burning Brakes
Joined: Jun 2003
Posts: 949
Likes: 0
From: smithtown ny
Re: Knock Retard Normal??? (C4Crazy787)
what's up?? okay i think i no why it worked for my friend when i told you he got a chip from tpis 1 or 2 things it does make sense. when they made his chip they took some knock retard away with reprogramming or they moved the knock retard above his max rpm range this way he will get no retard from idle to lets say 4800 rpms after that retard comes in . it has to do with this if i'm saying it right i don't no all i know is i do have engine noise betwwen my headers valvetrain and injectors it is definitly false retard i read a post that said to detect false retard get some 100 octane put it in do wot if you get retard it is more than likely it's false but if it don;t it's mecanical
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: Knock Retard Normal??? (6spd)
I found this link on desensitizing the kS, but I can't un-zip the download file. http://www.charm.net/~mchaney/f-tech.htm
Go search the word "knock" you'll find all kinds of stuff. I tried searching "knock retard" and got nothing. :seeya
Go search the word "knock" you'll find all kinds of stuff. I tried searching "knock retard" and got nothing. :seeya
