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Time to identify once and for all the source of my FKC


xt2005bonbon
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Don't you agree though that whatever you put in the WGDC table below ~5-7psi of boost target don't do squat to the car's behavior? Am I correct in thinking that?

 

Here was mine, it made the care be tamer on highway (cruise control being less twitchy). Improved my MPG too. I would test some more but I'm 100% manual gate now.

http://legacygt.com/forums/attachment.php?attachmentid=263018&stc=1&d=1520992555

 

 

So if the knock is not due to open/closed loop transition or lean conditions, what is causing it you think? I know. Hard to figure that one out without driving the car yourself and listening/feeling it...

 

Since there is no knocking noise (can of beans rattle), and since adding or removing timing didn't make it stop knocking it is... wait for it... false knock.

 

Either you have something loose or your mods are making a certain resonance at that 2500 rpm. Mine did it only at 2100rpm or less, so when I saw 2500rpm I was concerned.

MPG_WGDC_001.png.5af5233344d375759d16018fc3e7834d.png

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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Here was mine, it made the care be tamer on highway (cruise control being less twitchy). Improved my MPG too. I would test some more but I'm 100% manual gate now.

http://legacygt.com/forums/attachment.php?attachmentid=263018&stc=1&d=1520992555

 

 

 

 

Since there is no knocking noise (can of beans rattle), and since adding or removing timing didn't make it stop knocking it is... wait for it... false knock.

 

Either you have something loose or your mods are making a certain resonance at that 2500 rpm. Mine did it only at 2100rpm or less, so when I saw 2500rpm I was concerned.

 

Thanks for sharing your WGDC.

 

I don't think it can be the mods because it was present before them (bone stock). The only 'mod' at that time was a killerb oil pick up tube.... Can't be that.

 

Let's assume for a moment that the knock is actually due to some parts of the engine block itself. Say it is due to a loose wrist pin. If that was the case indeed, do you think it would have lasted 40k miles?

 

Can you have some piston slap around that rpm range even with a warm engine??

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Thanks for sharing your WGDC.

 

I don't think it can be the mods because it was present before them (bone stock). The only 'mod' at that time was a killerb oil pick up tube.... Can't be that.

 

Reason I say mods is because they can change resonance of parts, they can also increase engine noise, making stock knock sensor maps too sensitive.

 

Re-Oil pickup, as long as nothing is loose there, shouldn't be an issue.

 

Let's assume for a moment that the knock is actually due to some parts of the engine block itself. Say it is due to a loose wrist pin. If that was the case indeed, do you think it would have lasted 40k miles?

 

I highly doubt loose wrist pins would make fake knock noise, I'm talking about literal nuts touching the knock sensor, I have to clean mine off every couple years because of damn mice.

 

I've seen posts where people saw false knock because their knock sensor wire was angled wrong and touching the engine block/transmission randomly.

 

Can you have some piston slap around that rpm range even with a warm engine??

 

Piston slap is only at idle. Piston slap while warm is scarier. On my Nissan if there was piston slap like noise at 2500-3500rpm that was a sign of rod planning to come out of your block in the near future.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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I highly doubt loose wrist pins would make fake knock noise, I'm talking about literal nuts touching the knock sensor, I have to clean mine off every couple years because of damn mice.

 

I remember I did clean the area around the knock sensor a couple times. Used a vacuum to clean all the debris around it. And yet, stick got this knock..

 

But I never thought about the wire angle and position. I will have a look.

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  • 3 months later...

Didn't read through the whole thread to see if you've done this but here is an idea.

 

Have you added the rear diff bushing inserts?

 

I've always had repeatable shift fbkc until I recently added the inserts. After installing them I can't make the fbkc repeat.

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