whats this so called engine knock??

[lakedude90]

ok so as some of u may know from my first thread. im am wanting to accuire a MS6

one think i am seeing from a few guys on here is there that there talking about this so called engine knock.....now idk about u guys but. with us probe guys, when we start heing a engine knock...thats not a good thing. so can you guys inform me on what this is about?

thanks alot

 

[coyfish]

Well engine knock is basically detonation outside the "norm" for where the A/F mix is supposed to detonate. This is usually a specific time. This results in excess pressure which can lead to bad things . . .

Sometimes partial knock just happens, especially in mazdaspeeds. USually at partial throttle which is often just a false reading. I sometimes see .3-.7 while normal driving and 1 (at highest) at WOT sometimes.

Knock at WOT is what you need to worry about. High levels can really lead to a lot of pressure which will bend your rods or worse.

 

[lakedude90]

sooooooo is it a timing issue?? or just somthing that theses cars do?
casue im totaly new to the whole turbo thing and the last thing i need to do is get on it and the car bend a rod or worse throw one threw my oil pan

 

[coyfish]

Well you could buy a gauge that reads engine knock like a dashhawk or a scan gauge. If your car is stock you shouldn't have any problems. Usually knock can be alleviated with proper spark plugs.

Knock is never good. Getting the occasional .1-1 reading is nothing to worry about but getting anything over 1 at WOT should be looked at. Not sure about the exact reasoning but sometimes the sensor reads knock (especially during normal driving shifts) that really isn't there.

 

[lakedude90]

yea i saw the threads about the spark plugs but it still seems that even tho u gue colder plugs it still seems to knock. i guess when/ if i get the car ill deff get a boost guage and this so called dashhawk. i hav never herd of a guage that did this

 

[ms6acton]

dash hawk it the best mod for this car. reads 100+ parameters, fuel economy, 0-60 1/4 mile times. and you can data log also

 

[tunersteve]

IIRC, knock is measured from an audible sensor, and can sometimes pick up phantom 'noise' which interprets as knock. Also, the PCV system, according to some, until modified (Mazda is working on a fix) can also cause/contribute to knock.

 

[Blendercloud]

This engine platform has an extremely sensitive knock detection system. I believe Mazda wanted it this way to stay on the conservative side for a new engine design (which this is).

With most knock, you will not notice much. Maybe the engine hesitates slightly because of a brief interruption of power (ECU pulling some timing). Those typically aren't what I would consider real knock.

Real knock is an event in the engine where you do indeed encounter pre-ignition (numerically a much higher value on your AccessPort and DashHawk). You will hear and feel this event; and when you do it will make you a little nauseous.

Provided you are not designing your own ECU maps, not using lower octane fuels, and aren't driving in the middle of the Saharan desert, this Real knock that I'm talking about is very easy to avoid.

 

[lakedude90]

ok i think im getting it now. but i have seen some people tall about how adding a part to there car has increesed knock noise. but then once u go one step colder in spark plugs that it will help??

i think in reality im proly over thinking all of this but i just want to make sure i dont do anything stuipid and that i have my facts straight cause i kno when i get it im going to mod it and my parents will be all over my ass asking questions.

 

[8.5MS3]

you will only need colder plugs when running higher boost pressures. aka a tune. simple bolt ons usually do not require this upgrade

 

[lakedude90]

ok. well thats good to kno. i guess i could do it as a procaution tho.

 

[8.5MS3]

ok. well thats good to kno. i guess i could do it as a procaution tho.

i wouldnt. if theyre too cold you will get deposits on the plugs and they will foul quickly

 

[lakedude90]

gotcha

 

[ms6acton]

one step is actually fine with just regular bolt ons. before i installed mine i asked my mazda tech and he recommended one step colder haha.

 

[KTsuchiya]

BUying the MS6

ok so as some of u may know from my first thread. im am wanting to accuire a MS6

one think i am seeing from a few guys on here is there that there talking about this so called engine knock.....now idk about u guys but. with us probe guys, when we start heing a engine knock...thats not a good thing. so can you guys inform me on what this is about?

thanks alot

Well dude, you're going to have to own the car before you know what any of us are experiencing. If not, you're going to have to borrow one and drive it for a week, and even then you'll only experience it if the car suffers from it.

 

[lakedude90]

yea im deff sure about that. its just one of those things that u have to wittness for ur self im sure. i just want peoples input on it just to see how much a prolem it could be or is in general

 

[skarab]

not sure if this is the same, but a couple of times I have gotten onto the expressway and decide to give some more throttle and the car will stutter and I will hear a noise like sand blasting in my wheel well kind of a noise. Is this the engine knock? Yes I am completely stock and heard this twice now.

 

[skarab]

anyone?

 

[coyfish]

Could be a couple of things. There is a TSB and a reflash for some older model speeds with a "hesitation" issue. I haven't experienced that so im not sure if thats your problem. Not sure what type of sound your describing. Also engine knock is audible and you definately feel a drop in power. The ECU pulls timing. Perhaps thats what you experienced. I got really bad knock once and it felt like metal rattling around in the engine bay for a split second.

 

[tunersteve]

Could be a couple of things. There is a TSB and a reflash for some older model speeds with a "hesitation" issue. I haven't experienced that so im not sure if thats your problem. Not sure what type of sound your describing. Also engine knock is audible and you definately feel a drop in power. The ECU pulls timing. Perhaps thats what you experienced. I got really bad knock once and it felt like metal rattling around in the engine bay for a split second.

I think people have the misnomer that all knock is bad. Knock that the DH or other datalogging tool is not entirely bad. Yes, you will see knock 'spikes' from time to time under certain driving conditions, as the ECU will actively adjust fuel & ignition to optimize itself for that particular situation. It does this actively and will occasionally show up as knock. Pinging (as some refer to) is severe knock, which is what you need to worry about. This is much different than simply seeing knock on your DH.

I suggest if you're one who can, remove knock from your DH and drive normally, not looking at it. You should NOT notice any kind of hesitation or stuttering under any conditions. If so, the reflash/CDFP TSB may be the answer you're looking for.