what is knock?

[sleepygreen]

yeah bfor i went to bed lastnite i meant to post this question but i knocked the hell out but yeah wat is knock, as in knock sensor and stuff... is it the tapping noise when i have my car started?

[deevergote]

Knock can be describing two major problems.

The most common is detonation, also referred to as "pinging" (because when it's not severe, that's what it sounds like). Detonation in an uncontrolled burn of air and fuel in the cylinder. It is caused by hot spots due to piston or cylinder head damage, a lack of fuel to control the burn (the oxygen is what you burn... the fuel keeps it under control), or an improper spark. When detonation gets severe, it can knock... and at this time, it's probably destroying your motor. It's like a grenade in the cylinder.
Mine was knocking terribly due to a spark plug being pushed up in its hole.

The second type is more of a real knock. Rod knock. This comes from the rod bearings giving out, resulting in the rod actually knocking against other parts. A motor that runs with rod knock doesn't have long... If your rods are knocking, you need to rebuild or replace the motor before you put one through the block.

[Flatline]

and futhermore, a knock sensor is for VTEC engines to prevent pre-detonation by retarding ignition timing through the computer. A lot of people with tuned engines don't use one because when it does this you lose a little power.

I for one would keep it because no time in the world is worth the time it takes me to fix that engine, or the money it'll make me spend.

[deevergote]

I'm quite sure MRX deactivated mine when he tuned my P28... I never got a CEL when my engine was knocking, and there's absolutely NO way that knock sensor wouldn't have picked that up!

[sleepygreen]

so pretty much when you start having knock you should get it checked out rite. I had it confused cus i thought the knock sensor was making sure the knock doesnt get out of hand... but yeah i never really see anything about knock, thanks guys.

[deevergote]

The knock sensor is there to pull spark or richen the fuel mixture if it detects spark knock. It can't do anything about rod knock.

[GT-101]

If you have rod knock, usually it is very prominent. You need to get it checked out, but if you can hear it, more than likely it is too late. I've heard some people have used lucas oil stabalizer and it helps with the problem.

[deevergote]

It won't fix it, though. It may give you a little bit more time... very little. If you have rod knock, you definitely need new bearings. You may need new rods and rod bolts. You may need to resurface or replace your crank. If you let it go too long, you'll put a hole in the block. Game over.

[92accordcb7ex]

hmmm lately i have been hearing a knock in my car but its only after 2k rpm. i have a exhaust leak at the header and down pipe i think the downpipe might be a little loose now but i doubt thats it. and for some reason it sounded like it was coming from the IM.

[brand0n327]

hmmm lately i have been hearing a knock in my car but its only after 2k rpm. i have a exhaust leak at the header and down pipe i think the downpipe might be a little loose now but i doubt thats it. and for some reason it sounded like it was coming from the IM.

the same thing happened to me...then a week later i threw a rod bearing...take it easy or you will regret it...

[deevergote]

Feel your spark plugs. Make sure they're all tightened properly (but be careful not to overtighten)

[wed3k]

i never actually felt a "knock" but once the cel for the knock sensor came on, it would bog the hell out of the car.

got a chipped ecu and it ran great.

[crusto2k3]

would using your ngk plugs from the f22 in the h22 cause the knock sensor to come on, or would a bad gound set the knock sensor off?

[buckysaccord93]

would using your ngk plugs from the f22 in the h22 cause the knock sensor to come on, or would a bad gound set the knock sensor off?

arent they the same spark plugs anyway? if so.. than it could be because your spark plugs are shot and you need new ones anyway

[deevergote]

Improper plugs can cause detonation, but probably not in that case. It's more of a problem with forced induction, and running plugs that are too "hot"

Regardless, get the proper plugs. They aren't expensive.