Knock Knock driving me crazy.

[Brer Rabbit]

Well I put straight 114 octane into the tank after draining the 93 out and took the car for a blast. The car is still indicating knock on the ANS detector. Ive checked and double checked for anything that could be hitting the block or the downpipe and still cant find the cause. The knock seems to come on when I get into it pretty hard and since the car spools up real fast the knock comes on right away. Just changed the knock sensor for the hell of it and torque it to 14 ft. lbs but the same thing is going on. So now I need to know if a noisy valve train(roller rockers and lifters) and or a slight exhaust leak would cause my knock detector to light up at me. Im about to lose my mind here ....please help. By the way the most recent test pass was only 13 pounds of boost on that 114.

[QUIP'6']

Originally Posted by Brer Rabbit

Well I put straight 114 octane into the tank after draining the 93 out and took the car for a blast. The car is still indicating knock on the ANS detector. Ive checked and double checked for anything that could be hitting the block or the downpipe and still cant find the cause. The knock seems to come on when I get into it pretty hard and since the car spools up real fast the knock comes on right away. Just changed the knock sensor for the hell of it and torque it to 14 ft. lbs but the same thing is going on. So now I need to know if a noisy valve train(roller rockers and lifters) and or a slight exhaust leak would cause my knock detector to light up at me. Im about to lose my mind here ....please help. By the way the most recent test pass was only 13 pounds of boost on that 114.

13 psi with 114 would run way to rich

[Paul Clark]

As I am experiencing the same problem, would someone please explain to me how you can get knock from running too rich, and/or using too high of an octane or too much alky?
I would guess that running too rich would make a car bog and smoke, or would cause a loss of power and fouled plugs - but why would it cause detonation?
Unless it is false, higher octane and/or alky is the cure or preventative for knock - right? How can it be the cause?
I'm with you, lpaulabbott, in that I'm losing a part of my mind on this.
But I didn't have much to begin with.

[DCVING 6]

Originally Posted by lpaulabbott

13 psi with 114 would run way to rich

The octane level should have nothing to do with how rich the car is.

[QUIP'6']

Originally Posted by DCVING 6

The octane level should have nothing to do with how rich the car is.

running rich will cause detonation because its like trying to compress a liquid because your not burning all the fuel also you need to run high boost and timing for race gas because of the fuel properties BELIEVE ME I HEARD IT A MILLION TIMES BEFORE

[QUIP'6']

Originally Posted by DCVING 6

The octane level should have nothing to do with how rich the car is.

LOW BOOST WILL CAUSE HIGH EGT'S 1700 TO 1800 RUN HIGHER BOOST OR TIMING THEY WILL GET DOWN TO 1550 TO 1600

[DCVING 6]

Originally Posted by lpaulabbott

running rich will cause detonation because its like trying to compress a liquid because your not burning all the fuel also you need to run high boost and timing for race gas because of the fuel properties BELIEVE ME I HEARD IT A MILLION TIMES BEFORE

OK, but what does the 114 octane have to do with being rich?

Originally Posted by lpaulabbott

LOW BOOST WILL CAUSE HIGH EGT'S 1700 TO 1800 RUN HIGHER BOOST OR TIMING THEY WILL GET DOWN TO 1550 TO 1600

Why would low boost cause higher EGT's? I run 110 in my car all the time. Whether I run 14psi, or 24, my afr is a consistant 11.4-11.5, no knock either way.

[Alaskabuick]

If I hammer my car from a roll say 20 mph and it down shifts I will always get knock and more knock when the car gets up in the rpm range and then on the shift. Winding out in 3rd the knock goes away. This is all due to valve train and the jolt of the down shift, tires breaking loose etc. It used to freak me out at 1st but now have learned to ignore it. Roller rockers and differnt valve train from stock will set off you knock sensor from what I have been told.

My test for true knock now is to roll on in 3rd past the point where it can down shift to 2nd. I hammer it for a long hard pull all the way up to 25 pounds. I watch for knock, if I have knock I turn up my alky. If I am not running the alky I will adjust my boost or easier yet lower my timming on my FAST.
Not sure all what you have in your car. But this has worked for me.

Look at it this way, you have 114 octane, I dont think their is any way you would knock with that fuel at about any timming or boost that is within reason? Just my 2 cents, no expert.

Dennis

[83ttypecooled]

Hi,
I am also having a hard time comprehending how a rich mixture can cause detonation. I guess extended operation with this problem would cause a lot of combustion chamber deposits, but aside from that, I don't get it.Any other explanations?

[DCVING 6]

Originally Posted by 83ttypecooled

Hi,
I am also having a hard time comprehending how a rich mixture can cause detonation. I guess extended operation with this problem would cause a lot of combustion chamber deposits, but aside from that, I don't get it.Any other explanations?

Common misconception is that knock is all the same. The following link has some good reading on the subject.
http://www.streetrodstuff.com/Articl...tion/index.php

[Sinful6]

Brier Rabbit,

I really think we all need more information to answer your question.

Do you have a torque strap on the car? These are aftermarket and pass through the bolt hole in the alternator and rachet down to keep things in place. They make a difference, and before I installed mine on a past buick, I noticed the same symptoms that you have. Also, what is your turbo? I doubt 14psi would cause knock with 114 even with a T76 sized turbo, which leads me to believe you may be running excessively rich or lean(as previously stated), or that your sensor is picking up false signals(see torque-strap above). I know some guys with "noisy drivetrains" have had to relocate their knock sensors with success, however aftermarket solutions would be your best route for longevity, and protectino of your investment. What are your EGTs under WOT/during knock?


-D

[Brer Rabbit]

Originally Posted by Sinful6

Brier Rabbit,

I really think we all need more information to answer your question.

Do you have a torque strap on the car? These are aftermarket and pass through the bolt hole in the alternator and rachet down to keep things in place. They make a difference, and before I installed mine on a past buick, I noticed the same symptoms that you have. Also, what is your turbo? I doubt 14psi would cause knock with 114 even with a T76 sized turbo, which leads me to believe you may be running excessively rich or lean(as previously stated), or that your sensor is picking up false signals(see torque-strap above). I know some guys with "noisy drivetrains" have had to relocate their knock sensors with success, however aftermarket solutions would be your best route for longevity, and protectino of your investment. What are your EGTs under WOT/during knock?


-D

Im running a drivers side H and R mount, a stock pass. side mount, poly trans mount, nothing else. the achy has not even been out of the box at this point. Im gonna check the travel of the block today under load when a buddy comes by. Guys thanx for the insight so far, Its strange how I tend to overlook the simple things just because I used certain parts.

[Lee_Burough]

If you have some carbon build up, it glows red hot and predetonates your air/fuel charge....Ergo, you have knock.

You might want to treat the car for carbon build up. The treatment won't hurt anything. I use chevron Techron fuel system cleaner periodically. For the first treatment, you should try some GM Top Engine Cleaner.

Good Luck.

[QUIP'6']

Originally Posted by DCVING 6

OK, but what does the 114 octane have to do with being rich?




Why would low boost cause higher EGT's? I run 110 in my car all the time. Whether I run 14psi, or 24, my afr is a consistant 11.4-11.5, no knock either way.

Too Much?

[Razor]

Chasing knock problems

this may help