2fastSS

like you all are saying that knock is bad, even though this is a newb question haha dont flame me for it im being serious?

D4u2s0t

to sum it up as easy as possible, your engine is not burning all of the gas, which causes vibrations known as "knock"... happens usually when you're running too low of an octane, and your engine is burning the gas too quickly before it's all actually in the engine... octane is the resistance to detonation, nothing else... so, if your car calls for 93, just as an example, and you're using 87, the gas is being burned too quickly... it's ignited before it is ready

Bad06SS

iTrader: (1)

Knock or KR, is Knock Retard. When you're getting knock, it's an explosion in the combustion chamber (basically inside the engine). On these cars you can get it from running too much boost witout enough fuel, too lean, or possibly too much timing. Your AFR has to be safe to prevent it. Your car has knock sensors that pick up this pinging, and then it will pull back timing advance to help.Without getting too technical and typing an entire page on it, that sums it up.

D4u2s0t

that's the more complicated way to say the same thing i did!

Bad06SS

iTrader: (1)

Yes it was. I didn't see your post when I made mine.

BlackyK

Gas vapor inside the cyclinder is combusting before the piston reaches its highest point, exploding before it should. A precursor to your car going boom if you don't do something about this.

D4u2s0t

i think we did it at the same time!

beamSS

can you hear it when it happens? cuz i think i am hearing a rattling sound(maybe the valve. idk) when i floor it at 2000rpm.

SLOWBALT06

dont listen to anyone that doesnt drive a supercharged car seriously and when knock happens it cuts your exhaust sound youll be flooring it and all of a sudden everything will get quite and there will be a hicupp and you will be flooring it again going the same you were there was just a hiccup

beamSS

thnx man

leviticus88

Oh damn... That happened last night.

D4u2s0t

hahaha!! so you're saying that ONLY people that have a supercharged car know what knock is?? in what world is that true?? i feel bad for you man...

D4u2s0t

a) he asked what knock is, I gave a good answer
b) you assume because i have a 2.2 i don't know what a blown car is like? you know what happens when you assume
c) knock can occur in ALL cars, not only those with FI

there was absolutely no reason whatsoever for your post to only listen to people with the 2.0. and this response is silly, and immature as well.

**edited quotes

Eddie

aight both of you stop. stay on topic. all cars can experience knock n/a or fi. stop bashing other members

sethallen

bump how much knock is acceptable/harmless?

how can you get rid of it without tuning if you're already running 93 octane

8cd03gro

knock is less dangerous on an n/a engine than a boosted engine. if you are experiencing detonation on a fairly regular basis with your car, something is wrong and it could cause some major problems.


for the thread starter, knocking or detonation is when the a/f mixture detonates before it is actually supposed to. instead of being ignited by the spark plug like usual, it ignites from either compression or heat. this can cause issues because it can cause major stress on the internal components of your engine.

sethallen

i'm getting b/w .7 and 2.4 degrees of knock when shifting

mods are stage 2, 2.8", and injen cai

patathSS

If it is during shifts it is probably false knock from mounts. If it is during WOT than it is real knock. Have you tried getting a tank of 100? If that makes it go away than it is real knock. I get some at really low RPMs because of solid mounts.

zinner

For the most part the spark plug fires before the piston reachs the end of the compression stroke henced being called spark advance.

Two kinds:
1) Spark Knock, spark fires and the flame front isn't even and the gas detonates all at once. The gas is supposed to burn in a consistant manor from the point of the spark outwards, if it's hot enough and the spark fires the gas may all burn at once.


2) Detonation: The gas start burning before spark plug even fires.

Brian MP5T

Knock is actually the onset of detonation.

Brian MP5T

No you might not hear knock, but you will hear and feel detonation..

sethallen

it doesn't happen at WOT, or near the top of the tach....just right after shifting, or when i hit the gas harder towards the bottom end of the tach