crcain

I'm under the impression most people on this board tune using either the stock ecu factory knock sensor or perhaps some other type of knock detection software. Is this method really more accurate than the human ear w/det cans etc?

For example, how does David Buschur, Al, AMS, etc listen for knock?

Ph3n1x

iTrader: (12)

The sensor is calibrated in the ECU to detect knock in different circumstances. I would use that over listening for it. But it may be wise to do both.

Big up!

Warrtalon

iTrader: (6)

Sure, just log your knocksums and timing. That's going to tell you more than listening to knock.

crcain

Warrtalon.. your not putting a lot of faith in the human ear. Let me ask you how you think top tuners tune cars without the factory knock sensor like Motec, Gems, Autronic, etc? You do know what det cans are right?

Also how well does the factory knock sensor system work with a car with 900 hp capable pistons, rods, crankshaft, wild cams, etc?

SwiftEVO

iTrader: (32)

My car is a very loud car. I have trouble with the stock sensor picking up on engine noise. I had to set it up for a pretty high voltage to pull timing or add fuel. I have the aem btw

--Josh

crcain

I've been curious about how well the knock sensor works on the AEM. Does it use the stock mitsu knock sensor? Is it good enough that people actually tune just with that?

David Buschur has a lot of experience with AEM and tuning. How do you listen for det Dave?

Ted B

iTrader: (6)

An experienced ear can be used to tune an engine, without electronic knock control. The downside is should a change in conditions occur that triggers detonation, it only takes a few good knock events (a split second) to tear up a perfectly good motor. Been there, done that.

As always, it's give and take, and the factory ECU does a great job of saving the engine from sudden death, albeit at the expense of a bit of susceptibility to false triggers.

I might point out that when better standalone makers (hurry up Autronic) get the ion sensing control feature in full swing, there will be no good reason to omit electronic detonation control for any application. Ion sensing is THE last word in knock control.

crcain

Thanks for the info Ted and I do agree, automated knock control is a nice to have. I run an SMD and SM4 and Ray at Autronic says knock control is coming soon for the SM4 so I am sort of interested in that.

What is "ion sensing" by the way?

Here is the gist of my question and I'd be interested in your opinion Ted.

1. For built motors, strokers, etc... do knock control systems like the stock mitsu one, AEM, Knocklink, etc actually work well enough to employ as a safety device (ie pull timing)? Do they even work well enough to tune with?

2. Do you really need that experienced of an ear to hear det with a good set of det cans? I've been giving it a try lately and thought for sure I knew what was and what was not det/knock... but then after more trials I got puzzled by some sound and now am not sure if it is massive det or just valve train noise at high rpms.

3. If you put an experienced tuner with det cans against the stock mitsu knock system, who would pick up on det first?

SlowCar

iTrader: (4)

ion sensing

http://www.fs.isy.liu.se/~larer/Projects/main.html

Ted B

iTrader: (6)

The SM4 is advertised as having an internal knock sensing capability option. I don't know the status of this option, or if it is available for the plugin SM4 (EVO9) board.

Better standalones typically employ some form of straightforward knock control systems that can be used effectively if programmed effectively (which isn't as easy as it sounds). They aren't as sophisticated as the factory system, but can be used to good effect nonetheless.

An experienced ear is one that can detect knock from valvetrain noise. It isn't always an easy thing to do. I once blew the headgasket on a turbo 2.3 Ford with detonation in 4th before I could react. I heard it as soon as it happened, but it was too late. That was a composition gasket, so it worked like a fuse. Had I used a metal gasket like the EVO, I probably would have blown the motor.

The stock Mitsu system will be as good or better at detecting knock as the most experienced human ear. The sensor isolates the frequency range typical of knock, while the human ear hears everything.

Ion sensing technology uses no sensor, but uses only the spark plugs as its 'sensors'. It constantly measures the resistance between the spark plug electrodes. At the onset of knock, before it is audible, ions are formed which change the resistance in the gap. The Ion Sensing system detects this, and can retard ignition before the knock actually occurs. This is a great system because it is impervious to engine noise, and less ignition retard cures knock before it occurs as compared to what's required to stop it after it occurs, due to hysteresis.

crcain

Surprised to hear this Ted. Without doing a test, I guess it is hard to say what is better. I think I'd like to try to put my headphones on my friends standard ECU car and see if I hear det before the mistu ecu reads a knock event.

My tuner has told me he'd never let anyone touch mapping a car without headphones... personally I agree with this sentiment.

In terms of standalones, I'd love to know exactly how good the AEM knock control is. If I knew it was good, I might consider it over my SM4. However, without actually playing with the AEM... it be hard for me to give it a try.

Ted B

iTrader: (6)

I probably should have used the term "should" as opposed to "will", but I have witnessed less sophisticated ECUs (e.g. Ford EEC-IV) removing timing before I was able to detect audible detonation, which IMO is favorable.

Opinions in this subject seem to vary, so your proposed test is probably a good idea. The primary weakness with a conventional KS has always been its ability (or a lack thereof) to discern preignition from mechanical racket. If I had a set of 'det cans', I'd be curious to test them myself.

Mark S

The manufactors knock sensors are in the terms of detecting knock within the noise/frequency that they have set it to, Once you change the spec/cams and effectivly noise you might as well throw the sensor out the window or be able to put the testing in to recalibrate in the software which is unlikely, As you would need either very expensive test equipment or the normal head phones but you would need to be experianced in what you are hearing,
Even down to the size of the pipe bolted to the engine will change the noise level and pick up more sound experiance plays a big part here also,
Most aftermarket knock sensors are working as noise sensors nothing more and they need to be calibrated to each engine spec, So IMO unless you are using the headphones while mapping you dont know whether the engine is knocking also diff types of fuel will change the knock noise and effect the knock sensor,
So if you were to ask me no headphones no mapping,
This thread could become a can of worms with everyones opinions they will be diff even the top manufactors/race teams/sensor manufactors have diff thoughts on what is right or wrong good or bad and you will find most revert back to the good old headphones if all else fails.

Mark

ryan0

iTrader: (2)

you pull the plugs and grab a magnifying glass.

Ted B

iTrader: (6)

Two comments:

- If the level of internal noise changes significantly, a retuning of the noise floor may be warranted. Of course, the higher the noise floor threshold, the more advanced the state of preignition until the sensor records enough voltage to log a knock event.

- The placement of the sensor also affects the ability of the sensor to avoid falsing. Been there, done that.