Frustrated with knock

[Sanch]

So I have my dashhawk lighting up everytime the car knocks and the car only knocks when I am in low rpms. Pulling away at a light or taping the gas. The car only gets knock when it isn't expecting you to get on the gas. Lets say i am on slowly applying pressure to the pedal and then i go wot. I get nothing. Then lets say I tap the gas after letting off. I get knock. Maybe this can help someone figure out what is wrong the car. I heard its common but it can't be good. I heard companies like cp-e are trying to figure out what it is but man anyone know if you can just tune it out.? Any answer to this? Am I screwed is this the price I pay for moding the car. What is it.

[bova]

i would change it so it only goes off over 2

[Sanch]

Its bullshit though it shouldn't be happening.

[bova]

its not bullshit bud, thats how it works. its not a big deal we all deal with it. anything under 2 isn't anything that bad.

[kingpin748]

Well it is kinda bullshit but that's the way it is. It's normal for this car.

Change the alarms like was suggested.

[bykeryder4life]

I can get my car to knock on occasion just free revving the motor. I get little bits all over the rpm's at cruise. It's all normal for this car. its even been debated if its actual knock happening or the ecu pulling timing because it thinks knock is about to happen....Just worry about any knock you get while under boost/load..

[skeeter149]

check inlet tightness?

[subparpunk03]

Welcome to the club homie. I noticed SIGNIFICANTLY less part-throttle knock when I went back to the stock bypass valve. There are some things to check... tighten clamps, make sure no leaks in the system, pull off the IM and make sure not too much carbon buildup.

Modern cars are built to run with a little bit of knock... thats why they have the knock sensors, so they can run right on the edge of knock and pull timing before any serious damage is done.

These cars knock a good deal even in stock form... so just be wary of WOT knock.

[bykeryder4life]

Originally Posted by skeeter149 check inlet tightness?

ya I do every once in a while it always comes loose. soon will have an inlet with tbolt clamps so no more worries

[kingpin748]

Knock happens.

[wisniaPl]

just dont look at dashawk

[Sanch]

I should just not look at the dh

[kingpin748]

Originally Posted by Sanch I should just not look at the dh

It's kinda like Hepatitis. Nobody wants to be reminded about it.

[superskaterxes]

part throttle knock is no big deal because there isent enough cylinder pressure when it happens for any damage to occur. the knock sensor on this car is also very well calibrated so the knock is def occurring but shouldent be something to worry about.

[bova]

i believe part throttle knock is how the car maximizes its fuel efficiency which is why a lot of us will see it on the highway. the car keeps advancing timing for the best gas mileage and then it gets some knock and backs it down a bit and the cycle continues always trying to reach that optimal fuel efficiency, so technically it is not bad unless you can hear the detonation occurring.

[Fobio]

Originally Posted by bova80 i believe part throttle knock is how the car maximizes its fuel efficiency which is why a lot of us will see it on the highway. the car keeps advancing timing for the best gas mileage and then it gets some knock and backs it down a bit and the cycle continues always trying to reach that optimal fuel efficiency, so technically it is not bad unless you can hear the detonation occurring.

not only do I personally agree, I have others who have confirmed with Christian @ Cobb who've said that that is basically the case.

[subparpunk03]

Originally Posted by bova80 i believe part throttle knock is how the car maximizes its fuel efficiency which is why a lot of us will see it on the highway. the car keeps advancing timing for the best gas mileage and then it gets some knock and backs it down a bit and the cycle continues always trying to reach that optimal fuel efficiency, so technically it is not bad unless you can hear the detonation occurring.

If the detonation is bad enough to hear its a BIG problem.

You can be running 6 degrees of KR in the upper RPMs and not hear it... but thats damaging as well.

Just keep an eye on it... the occasional KR spike won't kill the engine, but if you are consistently getting 3.5+ degrees of KR during "spirited" driving... it may be something to worry about. Make sure you are using good gas from a station that has separate hoses for the different qualities (otherwise you get a hoseful of cat-pee gasoline mixing with the good stuff)

[bova]

i am not talking about spirited driving though. i'm talking about simple cruising on the highway which is where most of us get our random knock. if you are cruising at the same engine speed for a while the car will try and advance the timing until it gets its best gas mileage, but in this process it tags a little detonation so we see the knock retard. also i think that since we are maxing timing while cruising to achieve the bet gas mileage that when we do tap the throttle to get a little speed we only further advance it which is why we see that knock as well.

[ztuner]

all engines have noise. It appears the filter on the MS3 is not set to eliminate what we call phantom knock. If you are under no load and you touch the gas its highly unlikely you are getting real knock so i would suggest ignoring it.

Harry

[Superstretch18]

A couple of weeks ago, I installed an OCC, Denso ITV-22's and an ETS intercooler and knocking has been majorly reduced. I still get some random knocking, usually when BAT's are off the charts. If I had to guess, I'd say I'm only getting about 1/4 of the knocking that I used to get and almost never over 3 degrees (which used to be a daily occurrance). Couldn't say which is helping the most, as everything went on at the same time...

[stevessvt]

So I have my DH set to flash different colors for KR of 1, 2, and 3. I also get the flashes at only 1 I believe. Should I change it to 2, 3 and 4?

[phillyb]

fuck knock

[phantom3]

Originally Posted by ztuner phantom knock.

Is that when my car knocks?

[phantom6294]

Originally Posted by bova80 also i think that since we are maxing timing while cruising to achieve the bet gas mileage that when we do tap the throttle to get a little speed we only further advance it which is why we see that knock as well.

But, tapping the gas increases load which leads to a decrease in spark timing. The denser the air/fuel ratio, the less time it needs to burn.

[slo4now]

Knock sucks, i use torco Race fuel additive and i have 0 knock 24/7.



But according to everyone else on this board it's not worth it.

[bova]

the spark advance does not always correlate to the degrees of knock retard, in some instances the timing continues to increase even though knock is at 1. this log was done in 6th gear.

[DaleNixon]

Another knock thread! Sign me up!

[phantom6294]

Originally Posted by bova80 i believe part throttle knock is how the car maximizes its fuel efficiency which is why a lot of us will see it on the highway. the car keeps advancing timing for the best gas mileage and then it gets some knock and backs it down a bit and the cycle continues always trying to reach that optimal fuel efficiency, so technically it is not bad unless you can hear the detonation occurring.

If this were the case... then you should have little trouble proving it. Simply find a level stretch of road, set the cruise, and log RPM and Load so as to show a static set of engine operating parameters and rule out any spark advance changes due to changes in RPM and Load. Also, obviously, log spark advance and knock retard. If what you and others have said is true... it should quickly be established in a log that spark advanced is continually increased until the onset of knock and you would have a nice 'wave' of spark advance while cruising; up and down, up and down.

There is a fundamental flaw in your logic -- the idea that continued advanced of the timing increases fuel economy.

Let me back up for just a moment. The reason is that we all know that a common tweak to increase power on traditional distributor type ignition system, was to advance the base timing a few degrees. The timing would be advanced under all other operating conditions. The logic behind doing so is that if the air/fuel mixture has more time to burn and thus burn more completely, then more energy can be extracted from the mixture. Normally, though, such a change might require a higher octane fuel be used. However, there comes a point where further advancing doesn't yield any additional power and eventually leads to knock. This concept is referred to as Minimum Spark for Best Torque (MBT). Every engine has different MBT for different operating conditions. So, from a power/torque perspective, continued advancing of the timing is pointless once MBT has been established.

So, from a fuel economy standpoint, it could be argued that the engine will produce the best economy when it is most efficient. It seems reasonable to conclude that if the engine is producing Best Torque it is making the most efficient use of the air/fuel mixture. Further advancing the timing beyond this point has zero gains and the potential to eventually reach knock. Fuel economy is not going to be affected because the amount of fuel entering the engine doesn't change, and thus the economy doesn't change. The only possible (but improbable) advantage might be that the air/fuel mixture has longer to burn and thus burn more completely resulting in lower emissions. However, I said this is improbable because it seems if a more complete burn would result in more energy being extracted and thus more torque, if you're at MBT... you can't really be creating more torque, now can you. Furthermore, advancing or retarding the timing away from MBT will most likely and eventually lead to a decrease in torque, which would is only going to result in lowering the effieciency and thus lower fuel economy.

So, fundamentally, and within reason, there is a fixed amount of air entering each cylinder per intake stroke. Thus, there is a fixed amount of fuel entering the cylinder as determined by the ECU so as to reach a mixture ratio of 14.7:1 as determined by the O2 sensors. Advancing the timing beyond MBT yields no advantages and has ZERO effect on how much air and fuel enter the cylinder which results in ZERO change in the fuel economy.

Perhaps I am putting too much faith in Mazda's programming of the ECU; I realize they aren't perfect but I think they knew what they were doing when they determined the timing tables for operating at cruise. Are you, and others, really implying that Mazda haphazardly picked some random spark advance settings for the car and just sent the ECU on its own to determine the best spark advance setting?

BTW - I'll be waiting on a log showing spark advance continually being increased, then reduced, then increased, then reduced while a car is at a sustain load while cruising.

[Phantom]

I get the known "Phantom Knock" at times it spikes to 5 or 6 at times. This is when I am on the gas at a constant amount, if I touch the gas or get off the gas a bit it stops. If I keep on the same position it eventually goes away. It will drop from 5 to 4 to 2.5 and then 0.

Anyone else with this same issue?

I have not seen any KR at WOT or hard acelerating.

[phantom6294]

Originally Posted by phantom6294 BTW - I'll be waiting on a log showing spark advance continually being increased, then reduced, then increased, then reduced while a car is at a sustain load while cruising.

I'm already tired of waiting... and did some logs myself. I drove back and forth on the same stretch of road. The road does have some very light grades, but it is consistent -- thus, the engine load remains pretty consistent. Cruise control was used to control speed. So, here is as constant of engine operating parameters as is likely. If the ECU continually cycled through advancing spark timing, then retarding then advancing, surely it would show up in this log. However, I see absolutely ZERO evidence of that. Zero, nadda, nothing. Spark Advance seems to be pretty damn locked to engine load. When engine load is constant, spark advance is constant. The second screen shot has some relatively 'significant' changes in engine load. Guess what, when engine load increases, spark advance drops. When engine load decreases, spark advance increase. EXACTLY AS EXPECTED. Never, not once, do I see spark advance ever increase without a corresponding decrease in engine load.

[bykeryder4life]

I see the phantom knock as well. Sometimes when I am cruising around and I let off the gas to shift the DH will quickly flash like 3- 6.0 then go right away. When I get on the freeway I get the same knock as well, if I am at a constant throttle it will flash some stupid high knock and if I stay on the gas it quickly goes down like 4.5-3-2-0 or whatever the #'s may be. I just always let off the gas when it flashes and that makes it go right away. As phillyb says FUCK KNOCK

[martyxattack]

i think all the knock i see is engine noise. ive never got knock at WOT. i get in 6th and set cruise control at 3k ill have 6degress of knock like 10 seconds at a time. thats the only times i see knock. cruise control set at 3 and ill knock all day long.

[Phantom]

Another thing to throw out there.

What rear motor mounts are everyone using?

My question is based on my buddy with a Cobalt was getting KR like crazy when he had motor mounts installed but after removal was not having any KR. He figured it was the knock sensor seeing the added vibrations from the mounts.

I am using a TRZ poly mount. Never tested for KR with the stock mount or any other. Other guys that I know have a Speed with different mounts are stored right now so I can't test with them at this point.

[phantom6294]

Originally Posted by Phantom Another thing to throw out there. What rear motor mounts are everyone using?

Though I am now running the AWR 88d for the rear, I had plenty of knock when I was still on the stock mounts, and a 100% stock car.

[Sanch]

Hmm so the car knocks stock!

[Sanch]

Another knock thread I haven't seen any other knock threads but i guess i haven't been here long enough.

[GongShow]

Knock it off!

Stock cars do knock, even non-boosted ones. Even though you want to stay on top of it and monitor anything abnormal, a little knock happens. If you could log an out-of-the-box NA Honda, Saturn, Toyota, etc..., you would see some knock too. But, because we pay really close attention to our cars and tweak them, we have heightened "spidey" senses. I honestly had myself convinced that the dash creaking and my radar detector mount was actually knock.

OCKD - obsessive compulsive knock disorder

[DaleNixon]

Got 8.1 briefly on the way to the gas station this morning to fill up. My driving on the way would make a grandma look like Tanner Faust. It wasn't audible; I'm not worried.

[bova]

while cruising the car trys to find minimum best torque which allows the car to run with best emissions, yes emissions suck but it seems that mazda has the car trying to find the point where it has the least, so in doing so the ecu will sometimes hit knock points but i was reassured from christian that knock while cruising is not dangerous since there is no cylinder pressure.

[Sanch]

Yeah I guess that knock is okay. What really shocks me is stock cars knock.