Knock control - Clear I-trim tables question

[TnF]

Hello. I have a question regarding knock clear i-trim tables function. If set to OFF will the ecu remember the knock values after several power cycles? Reason is that i want to use it as a way to identify ignition cells that produce knock while i'm driving daily without a laptop. This way after several drives i can go back and check if there is any knock and correct the ignition table. 

 

Kind regards

[Davidv]

Nah it doesnt store current values in memory after you turn the car off.

Turning off "clear I trim values" means that you can prepopulate the Itrim tables with numbers in your tune file.

And it will start with a high number and then reduce them as the car drives and sees no knock.

As opposed to starting at zero on the table and then increasing when it sees knock.

It doesnt build up a log over several days though.

Might be best to setup internal datalogging, at a low HZ rate so it can log for several hours, of just a few functions (Itrim values on your cylinders logged at maybe 0.1hz or something like that)

Edited June 19, 2016 by Davidv

[Rich RDE]

David is correct here. You will want to setup internal logging for when it hits certain points or say you are in a range of RPM. Their are many ways to set this internal logging up.

happy motoring!

[TnF]

Thanks i already set up internal logging and i know how to do this, i wanted to confirm. However since the tables are there either way can you give us a function were the values are persistent? Or is this impossible because the ecu can't just store these values without doing a full store? Can't we have persistent tables like long term trims for things that run in closed loop?

[Rich RDE]

So you are wanting to add some logic here? I think the boys could make this possible but there are going to be many multipliers and factors here. Run time vs knock vs threshold vs RPM vs MAP vs other things. This would be a Knock Learn section. Decay Rates, Learn up and Down values. Interesting!

Hopefully I am following what you are asking?

[Davidv]

Currently if you leave the car running for 10 hours in a row, you'll have 10 hours worth of accumulated knock adjustments.

But as soon as you turn off the car it's all gone.

He is asking if it's possible for the values in the table to be persistent after the ECU has been switched off, without having to log in with an ECU and "Store" each time.

[TnF]

So you are wanting to add some logic here? I think the boys could make this possible but there are going to be many multipliers and factors here. Run time vs knock vs threshold vs RPM vs MAP vs other things. This would be a Knock Learn section. Decay Rates, Learn up and Down values. Interesting!

Hopefully I am following what you are asking?

Currently if you leave the car running for 10 hours in a row, you'll have 10 hours worth of accumulated knock adjustments.

But as soon as you turn off the car it's all gone.

He is asking if it's possible for the values in the table to be persistent after the ECU has been switched off, without having to log in with an ECU and "Store" each time.

Yes exactly what you said David  But Rich yes that's a nice feature to implement actually since at the moment when you are trying to identify the correct threshold values for the knock tables even with a narrowband knock sensor it is very much a trial and error process (although on my setup i have already set them up pretty close to ideal). However when having a tuning session it is pretty much impossible to replicated all the conditions, so like David explained if the i-trim tables are persistent you may catch some knock where otherwise you would never see (and it is in my case like 3-5 cells on 2 cylinders i caught once). So if the tables are persistent then the engine will be more safe since some knock may happen in one drive, then next time you start the engine it won't have to run the advanced values and it will try to put more timing slowly saving you from potential damage