Tuning Out Knock Help
Sep 20, 2013, 09:54 AM
#1
Tuning Out Knock Help
I have read almost every thread regarding tuning, e85 and so on.
There are so many ways and I cant seem to figure out how to get rid of knock
people say add fuel, merlin says reduce timing, one thread I just thread said afr 12.1 was more knock resistant.
im trying to tune 93 octane before I switch to e85 so I can see how the power can increase with different ratios.
What is the most common way to get rid of knock but not sacrifice power?
There are so many ways and I cant seem to figure out how to get rid of knock
people say add fuel, merlin says reduce timing, one thread I just thread said afr 12.1 was more knock resistant.
im trying to tune 93 octane before I switch to e85 so I can see how the power can increase with different ratios.
What is the most common way to get rid of knock but not sacrifice power?
Sep 20, 2013, 11:26 AM
#2
Add octane. If you throw in higher octane gas and the knock goes away than you are beyond the limits of the fuel. You will either have to reduce boost or timing and you will lose power. If it doesn't go away you may have a false knock condition. Then you have to find what up.
Sep 20, 2013, 02:08 PM
#3
Add octane. If you throw in higher octane gas and the knock goes away than you are beyond the limits of the fuel. You will either have to reduce boost or timing and you will lose power. If it doesn't go away you may have a false knock condition. Then you have to find what up.
during spool up I aim 12.5-12.0, once boost sets in taper from 11.5-11.1 sometimes richer around 10.8 to be safe depending on boost levels.
thanks!
Sep 20, 2013, 02:43 PM
#5
Make sure theres nothing in the engine bay causing "phantom / false knock" check for anything that can be hitting metal on metal like the upper IC pipe shake it up and down if it knocks on the body of the vehicle that can trigger false vibrations and tip the sensor off.
Check heat shields if the car still has them at the o2 housing area. The downpipe can tag / hit the tcase.
Depending on valvetrain aggressive cams like kelford 272 / S3 for example have a very aggressive / quick ramp rate and cause false knock during spoolup.
I have direct personal experience with the knock sensor from 5 years ago when i switched to a built 2.3L engine & aggressive cams i could rev up and hit 36 counts doing nothing in my driveway. In spool it knocked no matter what due to the ramp rate of the cam design and the only way to eliminate that was to adjust the filter sensitivity.
Before adjusting the filter heres how you safely find out if its real or false.
1. Throw in some really high octane fuel in the car, lower the boost and make the tune very conservative where you know its 100% safe. If you're not sure whats safe or not pay for someones services like mine and ask for a very conservative / safe tune to troubleshoot a faulty knock sensor.
2. Do a pull. does it still pull timing out in that area where its happening? if so lower the timing more in that area.
3. does it pull even more out from what you just dropped it down to? another words does it keep removing the more you take out, it just keeps going lower and lower? if so you are stuck in a loop where you can sit there all day and it will just keep pulling it out more and more. the more you lower it the more it pulls down from that lower number.
4. once you determine its not real you can adjust your filter sensitively slowly and do a run and gradually make it so it removes the phantom / false knock from your car while still making sure you attain the ability of the sensor still with your particular setup in general of the false background noise.
5. You should understand how an engine works before adjusting these filters. If you plot and graph your "voltage" of the sensor (engine noise) you will see as your RPM's increase your noise level will rise. As long as its a smooth rise and has no spikes IE.. you are around a high 1 volt low 2 volt engine at high RPM, then all the sudden your noise doubles up to 3.8-4 volts that is something to be very concerned about. a ~1 volt spike increase out of nowhere not so much.
Most inexperienced tuners think once you adjust the sensor its going to deafen the sensor and not allow it to function properly. this is not true at all. anyone who has done hundreds upon hundreds of these cars will tell you how it works and it takes a lot of filter to fully deafen the sensor out depending on age of sensor / torque on block / vehicle setup (mods) and so forth & fuel.
On some testing vehicles on evo 8's ive still been able to detect detonation safely at 40 (YES 40 - this sensor was trash) filter level which is shocking to some inexperienced people. some 28 will fully disable the ability to detect an actual detonation event. Every engine has its own level of noise, thats why you must carefully adjust and make sure you dont over adjust. Most false knock occurs at low RPM, but evo 9 do have a issue mid range around the 5-6k area depending on cams.
Here is an example at very high logging rate in the AEM that displays the behavior of voltage vs RPM and how it increases as your RPM's go up. This is very clear there was an unnatural event in this pull at higher RPM due to the large spike that stood out quite clearly. In this particular case this was caused by a misfire (blowing out spark) on a 650whp+ setup on C16 race fuel.
Another example of a very zoomed out capture of the same vehicle after fixing plug gap:
If you find yourself having to raise the filter to high that it seems weird like the examples i posted above, then its time to replace the sensor and put a new one in. Making sure the sensor is torqued to spec when reinstalling. The torque spec of the sensor plays a direct roll in the way it functions so this must be done to install the sensor correctly to ensure it functions properly.
Typically 99% cars do not need to be adjusted higher then the normal filter level of "20" at higher RPM and downlow, typically between 15-17. Mid range should be kept stock as well which is roughly "18".
If you find yourself having to go outside these boundries and you are certain its not real and nothing is obvious in the engine bay banging on the block / etc then replace your knock sensor!
Hope this helped. If you dont consider yourself an advanced user its best not to tackle it yourself.
Check heat shields if the car still has them at the o2 housing area. The downpipe can tag / hit the tcase.
Depending on valvetrain aggressive cams like kelford 272 / S3 for example have a very aggressive / quick ramp rate and cause false knock during spoolup.
I have direct personal experience with the knock sensor from 5 years ago when i switched to a built 2.3L engine & aggressive cams i could rev up and hit 36 counts doing nothing in my driveway. In spool it knocked no matter what due to the ramp rate of the cam design and the only way to eliminate that was to adjust the filter sensitivity.
Before adjusting the filter heres how you safely find out if its real or false.
1. Throw in some really high octane fuel in the car, lower the boost and make the tune very conservative where you know its 100% safe. If you're not sure whats safe or not pay for someones services like mine and ask for a very conservative / safe tune to troubleshoot a faulty knock sensor.
2. Do a pull. does it still pull timing out in that area where its happening? if so lower the timing more in that area.
3. does it pull even more out from what you just dropped it down to? another words does it keep removing the more you take out, it just keeps going lower and lower? if so you are stuck in a loop where you can sit there all day and it will just keep pulling it out more and more. the more you lower it the more it pulls down from that lower number.
4. once you determine its not real you can adjust your filter sensitively slowly and do a run and gradually make it so it removes the phantom / false knock from your car while still making sure you attain the ability of the sensor still with your particular setup in general of the false background noise.
5. You should understand how an engine works before adjusting these filters. If you plot and graph your "voltage" of the sensor (engine noise) you will see as your RPM's increase your noise level will rise. As long as its a smooth rise and has no spikes IE.. you are around a high 1 volt low 2 volt engine at high RPM, then all the sudden your noise doubles up to 3.8-4 volts that is something to be very concerned about. a ~1 volt spike increase out of nowhere not so much.
Most inexperienced tuners think once you adjust the sensor its going to deafen the sensor and not allow it to function properly. this is not true at all. anyone who has done hundreds upon hundreds of these cars will tell you how it works and it takes a lot of filter to fully deafen the sensor out depending on age of sensor / torque on block / vehicle setup (mods) and so forth & fuel.
On some testing vehicles on evo 8's ive still been able to detect detonation safely at 40 (YES 40 - this sensor was trash) filter level which is shocking to some inexperienced people. some 28 will fully disable the ability to detect an actual detonation event. Every engine has its own level of noise, thats why you must carefully adjust and make sure you dont over adjust. Most false knock occurs at low RPM, but evo 9 do have a issue mid range around the 5-6k area depending on cams.
Here is an example at very high logging rate in the AEM that displays the behavior of voltage vs RPM and how it increases as your RPM's go up. This is very clear there was an unnatural event in this pull at higher RPM due to the large spike that stood out quite clearly. In this particular case this was caused by a misfire (blowing out spark) on a 650whp+ setup on C16 race fuel.
Another example of a very zoomed out capture of the same vehicle after fixing plug gap:
If you find yourself having to raise the filter to high that it seems weird like the examples i posted above, then its time to replace the sensor and put a new one in. Making sure the sensor is torqued to spec when reinstalling. The torque spec of the sensor plays a direct roll in the way it functions so this must be done to install the sensor correctly to ensure it functions properly.
Typically 99% cars do not need to be adjusted higher then the normal filter level of "20" at higher RPM and downlow, typically between 15-17. Mid range should be kept stock as well which is roughly "18".
If you find yourself having to go outside these boundries and you are certain its not real and nothing is obvious in the engine bay banging on the block / etc then replace your knock sensor!
Hope this helped. If you dont consider yourself an advanced user its best not to tackle it yourself.
Last edited by tscompusa; Sep 20, 2013 at 04:31 PM.
The following users liked this post:
4b11slayer (Oct 17, 2016)
Thread
Thread Starter
Forum
Replies
Last Post
miller121mx
Evo Engine / Turbo / Drivetrain
30
Sep 8, 2011 12:41 PM
YaroRS
Evo X Engine Management / Tuning Forums
23
Jan 28, 2010 05:38 AM