AEM and Knock - eg: Paul Nelson Datalog
On a car like mine det cans are pointless, too many things going on in just 8-9 seconds while on the track. The car is violent enough as it is,(noise wise from the side exit, wind, loud dogbox ect) so I doubt I would be paying much attention to det cans going down the track at full kill.
I've gotten my tunes down consistently enough that I feel safe with running the car on a base tune & nothing will go wrong. I have yet to spit a rod out of the block or kill a spark plug or a piston. (knock on wood
)Det cans are nice on the more lower hp street cars, cause you have time to pay attention to what your listening for.
Also good tuners that tune on dynos can see detonation on the dyno graph. If you know what you are listening for and know all the basics of what a motor likes/dislikes then det cans are not needed.
Detonation really can't be felt in the car unless it's ungodly amount of detonation. Detonation has a pretty distinctive sound to it, basically if your at WOT and hear something and have to ask yourself "what the hell was that? is that an exhaust leak?" then chances are it's detonation. It sounds like marbles in a glass jar, you can't miss it.
On street cars I would never take the knock sensor out of the car, too many variables from day to day and gas fill ups. Knock control becomes your best friend with a street car that is daily driven.
Last edited by evil_eagle; May 6, 2008 at 11:46 PM.
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Thanks for talking with me Evil I know you have a ton of experience so it's real nice that you take the time. The guy that tunes my car swears by det cans which he makes. It's a pair of ear defenders, rubber hose leading to about a 8" copper pipe bolted to the cylinder head. He has tuned Skyline in the 8's, cosworth motors to 200+ mph. As I said he swears by det cans.
It seems to me, when things are moving very, very fast, what can someone react to the quickest? Having all sounds removed (ear defenders) and then just waiting for a "tik" is very easy to do. Viewing a live datalog under hard g's is pointless I'm sure unless on a dyno.
In terms of reading plugs after each pass, would that not be tricky because once you get a bit of det and you don't lift... isn't it possible for it to all go south quickly because the bit of det causes more det?
If you could give the AEM active knock control a grade, 0-10, 10 being excellent knock control with very few false positives, what would you give it?
I keep waiting for Autronic to come up with knock control for the situation of bad gas or what not. I've tried knock block and not had much success.
Could you log raw knock sensor voltage and just simply have the ECU react if it hits above a certain threshold? Or must you have something like people have described here with the AEM, the record a baseline type of thing.
Finally, have you tried any other types of knock sensors like bosch, etc?
It seems to me, when things are moving very, very fast, what can someone react to the quickest? Having all sounds removed (ear defenders) and then just waiting for a "tik" is very easy to do. Viewing a live datalog under hard g's is pointless I'm sure unless on a dyno.
In terms of reading plugs after each pass, would that not be tricky because once you get a bit of det and you don't lift... isn't it possible for it to all go south quickly because the bit of det causes more det?
If you could give the AEM active knock control a grade, 0-10, 10 being excellent knock control with very few false positives, what would you give it?
I keep waiting for Autronic to come up with knock control for the situation of bad gas or what not. I've tried knock block and not had much success.
Could you log raw knock sensor voltage and just simply have the ECU react if it hits above a certain threshold? Or must you have something like people have described here with the AEM, the record a baseline type of thing.
Finally, have you tried any other types of knock sensors like bosch, etc?
On a car like mine det cans are pointless, too many things going on in just 8-9 seconds while on the track. The car is violent enough as it is,(noise wise from the side exit, wind, loud dogbox ect) so I doubt I would be paying much attention to det cans going down the track at full kill.
I've gotten my tunes down consistently enough that I feel safe with running the car on a base tune & nothing will go wrong. I have yet to spit a rod out of the block or kill a spark plug or a piston. (knock on wood )
Det cans are nice on the more lower hp street cars, cause you have time to pay attention to what your listening for.
Also good tuners that tune on dynos can see detonation on the dyno graph. If you know what you are listening for and know all the basics of what a motor likes/dislikes then det cans are not needed.
Detonation really can't be felt in the car unless it's ungodly amount of detonation. Detonation has a pretty distinctive sound to it, basically if your at WOT and hear something and have to ask yourself "what the hell was that? is that an exhaust leak?" then chances are it's detonation. It sounds like marbles in a glass jar, you can't miss it.
On street cars I would never take the knock sensor out of the car, too many variables from day to day and gas fill ups. Knock control becomes your best friend with a street car that is daily driven.
I've gotten my tunes down consistently enough that I feel safe with running the car on a base tune & nothing will go wrong. I have yet to spit a rod out of the block or kill a spark plug or a piston. (knock on wood
)Det cans are nice on the more lower hp street cars, cause you have time to pay attention to what your listening for.
Also good tuners that tune on dynos can see detonation on the dyno graph. If you know what you are listening for and know all the basics of what a motor likes/dislikes then det cans are not needed.
Detonation really can't be felt in the car unless it's ungodly amount of detonation. Detonation has a pretty distinctive sound to it, basically if your at WOT and hear something and have to ask yourself "what the hell was that? is that an exhaust leak?" then chances are it's detonation. It sounds like marbles in a glass jar, you can't miss it.
On street cars I would never take the knock sensor out of the car, too many variables from day to day and gas fill ups. Knock control becomes your best friend with a street car that is daily driven.
On a car like mine det cans are pointless, too many things going on in just 8-9 seconds while on the track. The car is violent enough as it is,(noise wise from the side exit, wind, loud dogbox ect) so I doubt I would be paying much attention to det cans going down the track at full kill.
I've gotten my tunes down consistently enough that I feel safe with running the car on a base tune & nothing will go wrong. I have yet to spit a rod out of the block or kill a spark plug or a piston. (knock on wood )
Det cans are nice on the more lower hp street cars, cause you have time to pay attention to what your listening for.
Also good tuners that tune on dynos can see detonation on the dyno graph. If you know what you are listening for and know all the basics of what a motor likes/dislikes then det cans are not needed.
Detonation really can't be felt in the car unless it's ungodly amount of detonation. Detonation has a pretty distinctive sound to it, basically if your at WOT and hear something and have to ask yourself "what the hell was that? is that an exhaust leak?" then chances are it's detonation. It sounds like marbles in a glass jar, you can't miss it.
On street cars I would never take the knock sensor out of the car, too many variables from day to day and gas fill ups. Knock control becomes your best friend with a street car that is daily driven.
I've gotten my tunes down consistently enough that I feel safe with running the car on a base tune & nothing will go wrong. I have yet to spit a rod out of the block or kill a spark plug or a piston. (knock on wood
)Det cans are nice on the more lower hp street cars, cause you have time to pay attention to what your listening for.
Also good tuners that tune on dynos can see detonation on the dyno graph. If you know what you are listening for and know all the basics of what a motor likes/dislikes then det cans are not needed.
Detonation really can't be felt in the car unless it's ungodly amount of detonation. Detonation has a pretty distinctive sound to it, basically if your at WOT and hear something and have to ask yourself "what the hell was that? is that an exhaust leak?" then chances are it's detonation. It sounds like marbles in a glass jar, you can't miss it.
On street cars I would never take the knock sensor out of the car, too many variables from day to day and gas fill ups. Knock control becomes your best friend with a street car that is daily driven.
Good Post.Knock sensors are double edged swords just like those who live off the AFR data from a Wideband.
Live on the edge with a knock sensor and you will die by it as well.
Reading the actual components involved with the combustion process is the only true way to know what is going on. One dyno pull at a time tells you very little. Back to back to back.... runs in various gears and in steady state will tell you more. BUT when you are logging runs at the track (drag or road course) THEN checking plugs immediately, will tell you everything.
Knock voltage will tell you NOTHING. Knock RAW on the AEM is what should be logged and scrutinized. BUT even then, a tuner with enough experience will know if he or she is going in the right direction.
I think det cans are useful for dyno tuning but I agree that running 9 sec 1/4 mi's they probably wouldn't be the best thing 
Some people (like my brother) have a really good ear for hearing the slightest bits of unsustained knock without cans. I have no idea how. Maybe my ears don't pick up that frequency.
Correct me if I'm wrong but when you're logging Engine Speed, Knock Raw, and O2 together, you have a much better chance of determining if you have real knock right? Because you can see if there is a dip in the RPM's or a lean spike in the AFR's?
Some people (like my brother) have a really good ear for hearing the slightest bits of unsustained knock without cans. I have no idea how. Maybe my ears don't pick up that frequency.
Correct me if I'm wrong but when you're logging Engine Speed, Knock Raw, and O2 together, you have a much better chance of determining if you have real knock right? Because you can see if there is a dip in the RPM's or a lean spike in the AFR's?
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I think det cans are useful for dyno tuning but I agree that running 9 sec 1/4 mi's they probably wouldn't be the best thing
Some people (like my brother) have a really good ear for hearing the slightest bits of unsustained knock without cans. I have no idea how. Maybe my ears don't pick up that frequency.
Correct me if I'm wrong but when you're logging Engine Speed, Knock Raw, and O2 together, you have a much better chance of determining if you have real knock right? Because you can see if there is a dip in the RPM's or a lean spike in the AFR's?
Some people (like my brother) have a really good ear for hearing the slightest bits of unsustained knock without cans. I have no idea how. Maybe my ears don't pick up that frequency.
Correct me if I'm wrong but when you're logging Engine Speed, Knock Raw, and O2 together, you have a much better chance of determining if you have real knock right? Because you can see if there is a dip in the RPM's or a lean spike in the AFR's?
Can it be agreed that even with the most trained ear... if you are audibly hearing knock with your naked ear then you are letting the car det too much?
Well for me every time I see knock on the sensor and pull timing to fix it I never could here it with my ear. I think with external dumps and loud exhaust if you can here noise its a ton.
Thanks for talking with me Evil I know you have a ton of experience so it's real nice that you take the time. The guy that tunes my car swears by det cans which he makes. It's a pair of ear defenders, rubber hose leading to about a 8" copper pipe bolted to the cylinder head. He has tuned Skyline in the 8's, cosworth motors to 200+ mph. As I said he swears by det cans.
It seems to me, when things are moving very, very fast, what can someone react to the quickest? Having all sounds removed (ear defenders) and then just waiting for a "tik" is very easy to do. Viewing a live datalog under hard g's is pointless I'm sure unless on a dyno.
Thats the thing about racing a serious car at a level like this, it's a gamble you take, most cars at this power level like mine are always going have a bit of knock, it's part of it's nature, the key is to keep that knock under control where your not scattering parts all over the track
In terms of reading plugs after each pass, would that not be tricky because once you get a bit of det and you don't lift... isn't it possible for it to all go south quickly because the bit of det causes more det?
Reading plugs comes with experience years after years, after awhile you know exactly what to look for, it's not something that everyone can do without knowing what to look for, but once you know what to look for then you can tune a car on edge by just reading plugs
If you could give the AEM active knock control a grade, 0-10, 10 being excellent knock control with very few false positives, what would you give it?
It depends really, some cars the knock sensor works wonders and will save your ***, I would say with cars over 700whp the knock sensor becomes like a problem child and tatal tells false information, on a 400-500whp car I swear by the knock control as it's very useful, but when you get a car with extremely loose tolerance's the knock sensor gets a bit jumpy as the motor is much noisier then just your everyday street car
I keep waiting for Autronic to come up with knock control for the situation of bad gas or what not. I've tried knock block and not had much success.
Could you log raw knock sensor voltage and just simply have the ECU react if it hits above a certain threshold? Or must you have something like people have described here with the AEM, the record a baseline type of thing.
The knock control on the AEM does have a threshold table that you build yourself, the baseline pulls we talked about earlier are exactly why you wanna make the base line pulls, then you draw the scale into the table and tell the ecu to pull timing/add fuel when the knock voltage goes over the drawn scale, once you feel comfortable enough with your knock table scale then you start to read the channel knock #1, knock #1 will report spikes anything over your knock scale that you drew into the table as mentioned
Finally, have you tried any other types of knock sensors like bosch, etc?
It seems to me, when things are moving very, very fast, what can someone react to the quickest? Having all sounds removed (ear defenders) and then just waiting for a "tik" is very easy to do. Viewing a live datalog under hard g's is pointless I'm sure unless on a dyno.
Thats the thing about racing a serious car at a level like this, it's a gamble you take, most cars at this power level like mine are always going have a bit of knock, it's part of it's nature, the key is to keep that knock under control where your not scattering parts all over the track
In terms of reading plugs after each pass, would that not be tricky because once you get a bit of det and you don't lift... isn't it possible for it to all go south quickly because the bit of det causes more det?
Reading plugs comes with experience years after years, after awhile you know exactly what to look for, it's not something that everyone can do without knowing what to look for, but once you know what to look for then you can tune a car on edge by just reading plugs
If you could give the AEM active knock control a grade, 0-10, 10 being excellent knock control with very few false positives, what would you give it?
It depends really, some cars the knock sensor works wonders and will save your ***, I would say with cars over 700whp the knock sensor becomes like a problem child and tatal tells false information, on a 400-500whp car I swear by the knock control as it's very useful, but when you get a car with extremely loose tolerance's the knock sensor gets a bit jumpy as the motor is much noisier then just your everyday street car
I keep waiting for Autronic to come up with knock control for the situation of bad gas or what not. I've tried knock block and not had much success.
Could you log raw knock sensor voltage and just simply have the ECU react if it hits above a certain threshold? Or must you have something like people have described here with the AEM, the record a baseline type of thing.
The knock control on the AEM does have a threshold table that you build yourself, the baseline pulls we talked about earlier are exactly why you wanna make the base line pulls, then you draw the scale into the table and tell the ecu to pull timing/add fuel when the knock voltage goes over the drawn scale, once you feel comfortable enough with your knock table scale then you start to read the channel knock #1, knock #1 will report spikes anything over your knock scale that you drew into the table as mentioned
Finally, have you tried any other types of knock sensors like bosch, etc?
If the knock is bad enough then yes you can see it in the RPM graph on the log if you look close enough. Although you really don't get lean spikes from knock unless it starts to make the car miss fire. Knock is more dependent on timing then anything. Fuel has some to do with knock, but timing is mostly the key when dialing in a car for no knock.
Ive tuned cars as lean as 11.9-12.0 on just plain jane 93 octane pump gas without having any knock, it's mostly when you start playing around with the timing that you start to see allot of knock. Do I recommend tuning to 12.0 a/f's with pump gas, no I wouldn't but if you know what to look for then you shouldn't have a problem.
I am using a Toyomoto knock sensor kit for the EVO. My data logs used to look the same with the factory Mitsubishi Knock sensor.
Now it looks flat unless there is actual knock.
I will post a few logs later.
Now it looks flat unless there is actual knock.
I will post a few logs later.
You sir are correct! Good Post.
Knock sensors are double edged swords just like those who live off the AFR data from a Wideband.
Live on the edge with a knock sensor and you will die by it as well.
Reading the actual components involved with the combustion process is the only true way to know what is going on. One dyno pull at a time tells you very little. Back to back to back.... runs in various gears and in steady state will tell you more. BUT when you are logging runs at the track (drag or road course) THEN checking plugs immediately, will tell you everything.
Knock voltage will tell you NOTHING. Knock RAW on the AEM is what should be logged and scrutinized. BUT even then, a tuner with enough experience will know if he or she is going in the right direction.
Good Post.Knock sensors are double edged swords just like those who live off the AFR data from a Wideband.
Live on the edge with a knock sensor and you will die by it as well.
Reading the actual components involved with the combustion process is the only true way to know what is going on. One dyno pull at a time tells you very little. Back to back to back.... runs in various gears and in steady state will tell you more. BUT when you are logging runs at the track (drag or road course) THEN checking plugs immediately, will tell you everything.
Knock voltage will tell you NOTHING. Knock RAW on the AEM is what should be logged and scrutinized. BUT even then, a tuner with enough experience will know if he or she is going in the right direction.
What I am waiting for is for OEMs to start using actual pressure sensors instead of piezoecltric sensors like we have in our cars. Our sensors are 'tuned' for the resonant frequencies of our specific engine dimensions and harmonics. Once you build your engine, bore it out, etc, then the sensor no longer 'fits' the engine anymore.
With a true pressure sensor instead of a piezoelctric sensor, their will be no phantom knock or background noise that can give false readings. That's the biggest problem, in my opinion, with the current tehcnology. That's why the knock algorithms in the stock ECUs are so complex, since it has to have routines to only monitor at certain crank angles and certain frequencies that may be due to detonation. I personally think the stock Mitsu ECU does a great job at it and is one reason why I don't personally like stand alones and using knock voltage. Knock voltage, by itself, is pretty useless.
Anyway, I thought I read somewhere that Toyota actually uses pressure sensors inside the combustion chamber for this. Is that true? Does anyone know of any OEMs or aftermarket companies that have this available?
Eric
With a true pressure sensor instead of a piezoelctric sensor, their will be no phantom knock or background noise that can give false readings. That's the biggest problem, in my opinion, with the current tehcnology. That's why the knock algorithms in the stock ECUs are so complex, since it has to have routines to only monitor at certain crank angles and certain frequencies that may be due to detonation. I personally think the stock Mitsu ECU does a great job at it and is one reason why I don't personally like stand alones and using knock voltage. Knock voltage, by itself, is pretty useless.
Anyway, I thought I read somewhere that Toyota actually uses pressure sensors inside the combustion chamber for this. Is that true? Does anyone know of any OEMs or aftermarket companies that have this available?
Eric
