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No longer a 3/S owner.
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Discussion Starter · #1 · (Edited)
HELP! KNOCK found when logging for the first time!!

I got my pocketlogger set up in my car and took a cruise to school (20 miles away) I started logging and everything was going very well, I could take the car up to redline at a peak boost of between .97 and 1.04 bar (around 14.5 to 15psi) My fuel upgrade that is installed is a Walbro 255lph fuel pump hotwired. The injectors and fuel controller I haven't installed yet. I can't attach the log since I'm at school, but here's the problem:

when I take the car up to redline in any gear except 5th I get 0 knock at all, but when I'm in 5th gear going around 60mph and floor it knock starts showing up quickly. I had to let off once because I got a knock count of 12 at 2062 rpms. This doesn't make sense! does it??? is this real knock? fake knock? I always thought that if knock would show it would do it at high rpm runs...but this only shows up when using high boost at low rpms. I don't think I'm getting more than 11 psi or so before knock shows up in 5th gear...its weird and has me worried. What's wrong? anything? Thanks a lot!
 

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Senior Fanatic
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6,011 Posts
Higher gears make the engine work harder (heavier load) because of the reduced mechanical advantage of the gear selection. Heavier load means increased chances for detonation.

Solution: accelerate in a lower gear. :) Fifth is like, what, double overdrive?
 

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Mod O' Day Pron
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4,021 Posts
Why are you flooring it in 5th gear? That's a cruizing gear. Chris might be better at analizing this one. I would think if it were fake/false knock, it would be around 3 or 4 count. PM him...

Sean
 

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You break em, we fix em
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1,266 Posts
Thats normal. Your engine is REALLY "lugging" to try to move the car in 5th at 2000RPM. Really you only car about 1-2-3. YOu can go through the traps at 115 mph or more in third! 4 and 5 are for highway cruising only. In fact, if you are getting 0 knock in third that is OUTSTANDING and you can probably lean it out a little or run a little more boost.

My car when tuned well I get a few knock counts in 2nd, quite a bit in third, sometimes double digits. This is not ideal, but as long as the knock count is single digits or so its nothing to worry about.
 

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No longer a 3/S owner.
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Discussion Starter · #7 ·
thanks a lot guys

thanks a lot guys, I'll keep it in mind. I appreciate the help. Today I'll beat her from 0 to 120 and see what kind of logs I get....I'm still running stock turbos but am getting no knock at 1 bar.
 

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No longer a 3/S owner.
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Discussion Starter · #8 ·
Jim-

and Jim, you ought to inject propane to fight off that knock, you could run that same boost and probably get 0 knock sums...maybe even 4 to 5 more pounds of boost out of those 15gs...I want you to try that propane setup DR has so when i buy you can help me tune it:p
 

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You break em, we fix em
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single digit or even 10-15 knock sum in third is nothing to worry about. Its not ideal, but I have 110,000 on mine with no problems. As long as it doesn't get severe enough to pull timing, your alright.
 
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