Can too much fuel cause knock?

[Justa231]

Sometimes, when I lightly step on it, I see knock on my Scanmaster. I do not hear any knock, but I've seen as much as 15 degrees.
My O2's are showing over 800. Usually 820-830 and I've even seen as much as 850's.
I'm I giving my engine too much fuel?
Full throttle is fine. No knock. I only see it cruising around.

 

[MistaScott]

It could be false knock. Make sure your crossover pipe isn't hitting anything and clears the downpipe and headers etc. Knock doesn't necessarily mean you are running lean. You may have enough gas but not enough octane for example. In your case, I think you are not dealing with real detonation. Does it knock during shifts?

 

[77tech9]

My o2s are always 800 or above, no matter what I do. I can put my FPR at like 40 and get knock, but still have an 800 o2.

It might be because of my alt, or my leaded gas.

 

[ijames]

Yes, too rich can cause knock (even with C16 - I've seen it). I've also seen some chips that have knock problems at part throttle. They will run fine at less than about 2 psi boost, and fine at wot, but get 5-10 deg of retard if you try to run say 5-10 psi boost at part throttle. That's why I preach digital driving: stay less than 2 psi boost, or go full throttle, don't try to run 5-10 psi boost. You can also get part throttle knock if your egr system is malfunctioning, but that usually happens at less than 2-4 psi boost.

 

[Justa231]

Thanks for the replys, they all make sense.
Octane is fine. always use 93, plus I have SMC's alky system.
Even if I use higher octane, same problem.
Doesn't anyone make a chip that eliminates this problem?
I've tried several chips including race chips with no avail.
It does knock during shifts. usually 2-4 dedrees.
Should I stop worrying about it?

 

[Turbo Brian]

did you check to make sure your DP isnt hitting somewhere like was suggested? even if it "looks" like it has clearance, you're motor mounts may be old and/or broken allowing the motor to move around a lot and cause the DP to hit.

 

[humberto]

Guys have had problems with part throuttle knock when the egr valve is disabled including myself.Got my chip reburned and so far so good.

 

[MistaScott]

Originally posted by Justa231
Should I stop worrying about it?

I would worry about it because any measurable knock (even false) will retard timing and hurt performance. Shift point knock is usually false however. It is possible your motor mounts are flexing when you shift and bringing the crossover into contact with something.

 

[TurboJim]

That you Nick?

 

[Justa231]

Hi Jim,

Long time no talk.
I hope all is well.
As you can see, I'm experiencing false knock.
Where are you working?
Same place?
Do you have a shop of your own?

Nick

 

[Justa231]

I am unable to locate anywhere (checked the down pipe, plenty of clearance) that may be hitting, that's why I feel my problem is due to too much fuel.
I also have a tie down and new motor mounts.

 

[TurboJim]

Originally posted by Justa231
Hi Jim,

Long time no talk.
I hope all is well.
As you can see, I'm experiencing false knock.
Where are you working?.
Same place?
Do you have a shop of your own?

Nick

A new shop about 15 mins from my old one. Actually, been there a year April 14th. Liking life again finally.

Hopefully have my car going in the next couple weeks (waiting for my converter now).

Hows thigns with you? Wife? Kids? Hows Dad? louie?

What hap;pens when you turn the boost way down? Still have knock? Is it only moderate boost? Does it knock at wot? May need to go in and tame part throttle stuff in the chip. Email me if ya wanna spend some time on it one weekend.

Jim

 

[Justa231]

Jim,

Sent you an email.

Nick