Seafoam?
Team Owner
Joined: Jul 2004
Posts: 28,499
Likes: 3,298
From: Hartford WI
Kinda makes me wonder if something is causing it. Maybe something like the AC or some other pulley is causing the vibration. Yes, the tensioner might be moving but if there is no load on it, could it be a bad harmonic balancer? Just throwing out ideas at this point. I would certainly try to see if the knock goes away.
I had a thought. If you run it from cold, the KS can still pick up knock whether it is in closed loop or not so that might give you an extra margin of safety.
I had a thought. If you run it from cold, the KS can still pick up knock whether it is in closed loop or not so that might give you an extra margin of safety.
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Why would you increase your timing to get rid of knock? I thought people had problems with knock when they increased their timing?
I seem to recall some guys setting their timing by increasing it till it knocked. Then they backed it off some. If it is already knocking, I don't understand why you'd increase your timing?
How do you confirm knock counts? The only thing I can think of is I
I seem to recall some guys setting their timing by increasing it till it knocked. Then they backed it off some. If it is already knocking, I don't understand why you'd increase your timing?
How do you confirm knock counts? The only thing I can think of is I
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Kinda makes me wonder if something is causing it. Maybe something like the AC or some other pulley is causing the vibration. Yes, the tensioner might be moving but if there is no load on it, could it be a bad harmonic balancer? Just throwing out ideas at this point. I would certainly try to see if the knock goes away.
I had a thought. If you run it from cold, the KS can still pick up knock whether it is in closed loop or not so that might give you an extra margin of safety.
I had a thought. If you run it from cold, the KS can still pick up knock whether it is in closed loop or not so that might give you an extra margin of safety.
I'm thinking it could be the EGR. As I can't pull a vacuum on my EGR when I checked it as it should since it is a negative EGR.
The things that usually cause spark knock (detonation) are...
(1) The EGR valve that is not working. The EGR valve is supposed to open when the engine is accelerating or lugging under a load. This allows intake vacuum to suck some exhaust in through the EGR valve to dilute the air/fuel mixture slightly. This lowers combustion temperatures and prevents knock. Inspect the operation of the EGR valve, and check for a buildup of carbon deposits on the valve pintle or valve port that may be blocking the flow of exhaust back into the engine. Clean off the carbon deposits with a wire brush and carburetor cleaner, or replace the EGR valve if it is defective.
I think I'll look at replacing the EGR.
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Also, if the tensioner is loose enough as to fool the knock sensor, you'd hear without opening the hood.
Quit barking up wrong trees and try getting under the hood..
SO get out there tomorrow and try bumping the timing up or down, and experiment.
Bring some tangable results back to this discussion.
Quit barking up wrong trees and try getting under the hood..
SO get out there tomorrow and try bumping the timing up or down, and experiment.
Bring some tangable results back to this discussion.
Last edited by JrRifleCoach; Oct 2, 2010 at 02:59 AM.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Also, if the tensioner is loose enough as to fool the knock sensor, you'd hear without opening the hood.
Quit barking up wrong trees and try getting under the hood..
SO get out there tomorrow and try bumping the timing up or down, and experiment.
Bring some tangable results back to this discussion.
Quit barking up wrong trees and try getting under the hood..
SO get out there tomorrow and try bumping the timing up or down, and experiment.
Bring some tangable results back to this discussion.
I'm gonna start by replacing the EGR valve since I know I can't pull a vacuum on it. And it looks like a malfunctioning EGR can cause knock on acceleration. As when accelerating, I do see in my scans it calling for 100% EGR duty cycle. So, I don't think it is getting that since I can't pull a vacuum to open the EGR valve. That looks like the best cause of knock other than it still having alot of 87 still in the tank.
As before doing anything other than the EGR, I planned to empty at least half the tank and fill with 93 so I can start with a tank full of 93 vs mostly 87 to help rule out octane. Then I'll go from there.
Team Owner
Joined: Jul 2004
Posts: 28,499
Likes: 3,298
From: Hartford WI
Could something else cause that rattle that is hooked onto the tensioner. I think running for a bit without the serpentine belt might shed some light.
My tensioner was making noise when the AC kicked on.
My tensioner was making noise when the AC kicked on.
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Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Doubt that would trip your sensor it supposedly picks up frequencies generated by detonation/spark knock itself. Fix the EGR that will def make it knock, if youre really ambitious clear the EGR passages in the intake base they are small holes a few inches inside the base port
