should i be worried about small amounts of knock?

[bluesman]

Originally Posted by AdamVR4

Those don't sound like scenarios that will produce knock.

Yes, it could be the mechanical noise of a drivetrain "lugging", i.e. jerking a bit if revs are too low. But that's accompanied by obvious jerkiness in the motion of the car. Open throttle at low revs with a full load (e.g. going uphill slowly) is a typical scenario in which detonation (true "knocking") occurs. The sound it makes is not at all like differential or any other drivetrain noise - it's higher in pitch, and used to be called "pinging" in the days of 101 octane pump gas.

It happens when the fuel-air mixture in the combustion chamber is ignited by a hot spot in the chamber rather than the spark plug, or when the mix doesn't swirl into the chamber and ignite exactly as designed. If the flame front starts in the wrong place and/or doesn't travel smoothly through the chamber as engineered to do, it puts aberrant pressure on the piston crown. So the piston is being pushed in a direction other than straight down the bore, causing vibrations that you hear as knocking or pinging. And this can cause actual breakage of hard parts (e.g. rings) in addition to the (more common) accelerated wear of bearings, wrist pins etc if allowed to continue over time.

All modern cars have knock sensors in them - these are mechanical sensors (actually very sensitive microphones filtered to pass only the frequencies in question) screwed into the engine block to "hear" the abnormal vibrations and tell the engine management computer to retard the timing in 2 degree steps until the knock goes away. This is how you can safely run on 87 (as long as your knock sensor and the computer are functioning properly), and it's why you lose power when doing so. The timing is rapidly retarded until the knock goes away. BTW, the reason for knock with lower octane fuel is that octane helps determine the ignition temperature of the fuel - the higher the octane, the higher the temperature required to set it off and the less volatile it is. So higher octane fuel is less likely to be ignited by anything other than the spark plug.

It's rare, but failure of a knock sensor is the commonest cause of pinging in otherwise OK engines. If you think you hear knocking, have the car checked - the OBD will have thrown an error code, and simple replacement is a quick easy fix.

[bluesman]

Originally Posted by DAEMANO

Jeezus, why do people even bother asking for help when they're just going to rudely shut down any idea that might include them in the issue?

New to the planet, eh?

I try to offer the facts when I can, dispassionately and without judgment (unless challenged by malevolent idiocy of mammoth proportions, which is fortunately rare). But we can't control the ears onto which our words fall.

I agree - it's probably not detonation. But the probability, no matter how tiny, is still greater than zero: a knock sensor could be bad, a chamber could have a small piece of foreign material in it, there could even be casting flash or another such rare build anomaly. And often blamed but almost never proved, it could even be the dreaded "bad gas". The definitive way to calm the OP and (if there's really something wrong, get it fixed), is to check it. If he's really got a bad knock sensor, he'll eventually have damage. None of us knows what's really going on there, and a free consultation that's devoid of fact is generally worth exactly what it costs (or less).

Why add more to the growing pile of turmoil? Please have it checked or stop talking about it, Basket Case. We all think and hope it's nothing major, and we look forward to learning what's going on.

[kiichiro]

Way too much LSD

[mav1178]

Originally Posted by Basket Case

I live in florida, the land of the flat...Every once in a while when i am not paying attention and i go up a really steep drive, or try and make a u turn on a steep driveway and just give it a lithe gas i have noticed a little knock . I have only noticed this twice thank goodness. Do i need to be worried about the affect of that? This isn't something that happens often. I guess sometimes i just forget I have no torque since i drove a mustang for so long...

The problem here is, what you are describing doesn't help one bit... hence the odd responses.

You aren't describing the scenario under which the knock occurs.
You aren't giving us info such as speed, gear selection, etc etc.
"Give it a little gas" = knock. What is that? 6th gear at 30MPH?
Is this only when you turn?

Why do you think it's knock? I know what you are referring to and to me, it's not knock.

Your "knock" is just lugging the engine. I can easily replicate the issue every morning leaving my house, and it is not an issue.

If it's related to starting from a stop, it's clutch chatter. This car has a relatively loud clutch.

But it would help if more details were provided. The first post was about as vague as one can get.

-alex

[OjiGeorge]

The board is still young, and some of the younger members tend to make a dramatic scene about near everything. They expect that because they get it, you get it, and thus are not very accommodating.

Take some logs, then we can look at your issue objectively. Also what Mav1178 said is spot on.

Remember, this is a young internet forum, on a new platform- not an encyclopedia of live expert help.

[OjiGeorge]

No question, just saying this car forum hasn't matured yet. People are not nearly as welcoming and friendly as they should be to fellow enthusiasts.

If someone wouldn't speak that way to a person's face, what does that say about the same person hiding behind a screen name?

[wheelhaus]

Good lord you guys are being a bit judgmental and "douchey" yourselves. Stop reading into the OP's responses so hard, and stop getting so damn defensive and aggressive. Everyone needs to learn something at some point and you pricks are being rather hypocritical because he's not asking the questions you think he should be asking, or asking them in the expected manner.

We're a family here, so how about we put the egos away and help each other out a little more?

Back on topic, from what the OP has described, I don't necessarily believe its knock, either, but more lugging the engine. Without seeing a video with decent audio this kind of thing is hard to diagnose, so it's speculation at best.

[dreroc-z]

Did you even bother to ask who it was?

[DarkSunrise]

I've noticed this engine makes a rattle-like sound at very low RPMs (under 1500 RPM) with some load. Perhaps this is what you're talking about? Note, this sound is different from detonation, which is higher pitched, like marbles in a can -- and usually doesn't happen at RPMs that low. I haven't heard this engine ping or detonate yet.