here ya go, you is welcome.

http://www.turbobuicknewsletter.com/...tbnbonus1.html

http://autospeed.drive.com.au/cms/A_0353/article.html



more infomation about knock detection.
http://pw1.netcom.com/~bsundahl/knoc...nockSounds.htm

 

Ok I understand what you are saying now. and I agree. So how does the ECU determine what is knock and what is background noise...because the knock sensor is in fact a crystal detector as I stated earlier.

 

The ECU has logic that learns and constantly adjusts to the background noise of the engine (up to a point) and pulls timing for any amount of noise above that learned threshold. The further above the threshold, the more the adjustment will be made, such as pulling ignition timing, increasing fuel, etc.

It is a very complex process that involves many variables and inputs, one obviously being the knock sensor, but others include the RPM, the particular fuel/timing maps that are being used at that moment, etc. Also, the ECU will keep these adjustments in effect for a certain amount of time (revolutions) depending on conditions.

But, basically the stock ECU does a great job...it's just that we can't see it happening, and that's why we want devices like a Knock-Link. Because even though the ECU is doing many things to react to the knock, when you modify our cars, that may not be enough. So, we need to know exactly what our knock thresholds are to tune close to, but not beyond, them.

If you really wanted to build a 'knock meter', build something that will flash a light or something when timing is being pulled by the ECU. That will tell you that the ECU detected knock. But, in order to do that, you would need to know the timing tables of the stock ECU based on the airflow tables that you are currently on (depending on RPM, load, etc) and be able to know what the timing should be and what the actual timing is. Anytime there is a difference, that would be because of knock.

The best product by far that I know of that does this is DSMLink. I have had it for years in my Eclipse, and I am tempted to put one into my Evo. But, I sort of want to wait for a native Evo version. But, I may just do it anyway.

Eric

 

That is teh smart. Build it and they will come.

 

well, you can't really detect knock...but with a pocketlogger you can log timing....and if timing is being pulled, there are knock events

there is no warning feature of course, and i think that is what we are looking for.

the DSM link is a great idea

 

does anyone have stock timing table at WOT. i have the pocketlogger but i need to know what the base timing to determing if the ecu pull timing or not.

 

Has anyone ever thought of making a voltage regulator to reduce the knock voltage seen by the ecu? Somewhat like a bass regulator for an amp? I know knock is important but a lil reduction in its pickup wouldnt hurt

 

TRUE.

 

I have access to some of it, but the timing table is dependent on load (g/rev airflow) and RPM, not just the fact that your are WOT.

Eric

 

i understand that ignition timing depends on all those parameters, i guess i'm used to looking at honda maps that use MAP sensor instead of MAF. couldn't you just look at the max load column (ie WOT) and trace to see what timing is at each rpm range?

 

If you were positive that you were at the max load column, then yes. But, a stock evo, and even a slightly modded one, isn't necessarily using the max load column. And throw a piggyback into the equation (which most tuning devices are..like ECU+, XEDE, S-AFC, etc), and you will be even further away from the max load column.

Piggybacks intercept the airflow reading before it gets to the ECU, causing the ECU to think that you are at a lower load column, and thus the ECU leans out the fuel and raises timing respectively based on the corresponding fuel and timing tables.

But, in any respect, looking at the EVO timing tables, there are a couple of very conservative columns at the highest loads, probably put in there by Mitsu for a safeguard.

Also, even though you are used to looking at maps with a map sensor, it's really the same thing even with a MAF. The maf frequency is just changed to an airflow number by the ECU based on intake temperature, frequency and barometric pressure, so all tables are basically load (roughly proportional to boost) and RPM.

Eric

 

so, how can you log timing and tune if you run a piggyback?

how do you know if the car is pulling timing, or if thats the actual timing you have it set to pull?

this could be a great lesson!

 

Now you are seeing why I hate piggybacks. They are too much of a guessing game when it comes to tuning. You need a tool that is able to read/modify the stock ECU instead of intercepting signals to it. But, I'm not bashing any piggyback products...they are good for what they do, but they just lack so much in important aspects of tuning.

The only way that you can log timing with a piggyback is to get another tool that can log OBD-II, such as a scan tool or pocketlogger, etc. Not to mention fuel trims, which are very important when dialing in larger injectors, etc. I'm not an expert on all of the piggybacks out there (my experience is with DSMLink), but they can't log timing or even proper airflow, since the piggyback is lying about the MAF frequency. I suppose you can easily find the airflow by simply multiplying by the correction factor, but as far as timing, the piggyback would have to be able to read the stock ECU, which I don't think any do. It's difficult to know what maps you are on in the stock ECU because of the intercepted signals from the piggyback.

While we are on the subject, too, there is no piggyback that can log/monitor knock properly either. I think the XEDE is making a great attempt at it from what I have seen, but knock is the most important aspect of tuning and you need to know how many degrees of knock retard the stock ECU is applying and at what RPM range. All piggybacks can do is monitor knock sensor voltage, which is just the noise heard by the stock knock sensor. You need to corellate that background noise into what is and what isn't knock. At different RPMs, the same amount of voltage isn't the same amount of knock, and may not be knock at all. The stock ECU has logic that dynamically adjusts what is acceptable concerning background noise, and pulls timing based on how far above that acceptable range the voltages spike. It constantly does this to monitor and react to knock events.

Eric

 

The ECU+ logs knock (the new version)
I've logged the knock voltage (still am) .. the voltage hangs around less than 0.5v regardless of rpm or load .. except around 4500rpms - 5500rpms.. where there spikes in the voltage from 1v to 3v .. not constant .. just like 2 or 3 peak spikes .. only thing is as rpm rises .. the voltage doesn't seem to climb at all and its the noisiest (around 0.5-0.8v) between 4500-5500rpms .. beyond that, the voltage drops to below 0.5v again

Your assumption seems to correlate with what I see on the knock voltage (regarding the number of spikes before ECU retards timing) ..

 

So, when logging timing while using a piggyback to tune with(logging with something like pocketlogger or similar) its nearly impossible to know if the timing values the motor is seeing are the timing values you have it set to see, or if the timing is something corrected by the ECU due to knock.

So, essentially, the only way to try to tune that way is on the dyno....where you can actually see dips in the power curve and try to find knock events. I really would like to be able to tune this thing on the street.

Could you get a true timing curve by logging a low boost pull with high octane....then upping the boost until you get to some knock and actually see timing pulled....just to make sure that the timing curve you actually saw is what you have it set to do?

that sounds kind of long-winded and confusing, do you guys get what im trying to say?

essentially, whats the best way to log a run where you will be guaranteed to see the timing you have the piggyback set to run?

-Jeff-