Nissan 350z / VQDE Knock Setup

[BeallJK]

2020-03-09 Knock Setup.pclrHey guys - 

Was looking for a quick confirmation on the Knock Setup within my G4+

Running a 350z VQDE and a mild boost setup running pump gas with the goal around 14psi and a race fuel with a goal of around 20psi.  

 

I understand the concept with the Knock Target table but as far as each 'Knk Ign Trim Cyl#' tables go, to confirm and so I dont make a dumb mistake and I didnt see this covered from a search.  

Will the 'Knk Ign Trim Cyl#' table will take negative numbers to retard timing and positive numbers to advance timing?    

For instance: when activated, a value of -3 in a given load & RPM cell will retard timing while a value of 3 would advance my timing after the threshold in the Knock Target Table is exceeded? 

For example: If my Main Ignition Table was 26 degrees BTDC timing and I experienced knock above my Knock Target Table threshold, and it's corresponding value was -3degrees, the Link would dial my timing down to 23 degrees for that particular cell??

 

when calculating my knock frequency (OEM piston diameter is 95.5mm and using the formula [(1800) / (3.1416 * dia)] = Frequency) 

1800 / (3.1416 * 95.5), 1800 / 300.02 = 5.9996, my Freq Channel should be set to 6khz??  It was defaulted at 4k to 10k hz.

 

Are there good threshold values to use for the 3.5 VQDE?  The G4 did have default values but I just wanted to double check.  

 

Is there any reason to advance timing in a knock event?  

 

As always - thank you for your help!  

 

 

[Adamw]

5 hours ago, BeallJK said:

Will the 'Knk Ign Trim Cyl#' table will take negative numbers to retard timing and positive numbers to advance timing?    

For instance: when activated, a value of -3 in a given load & RPM cell will retard timing while a value of 3 would advance my timing after the threshold in the Knock Target Table is exceeded? 

Correct.

The most common way to use it is have the "clear I-trim tables" set to ECU power on.  This zeros out all those tables at start up so the engine starts and runs on whatever is in the main ignition table.  Then only if knock is detected then some areas will be retarded and you will have negative numbers in the i-trim tables.  I dont see any reason to ever put positive numbers in those tables.  The ECU will never advance back further than zero.

 

5 hours ago, BeallJK said:

For example: If my Main Ignition Table was 26 degrees BTDC timing and I experienced knock above my Knock Target Table threshold, and it's corresponding value was -3degrees, the Link would dial my timing down to 23 degrees for that particular cell??

Yes, in that particular cylinder when operating in that particular cell it would have 3 deg less advance than the general commanded value.

 

6 hours ago, BeallJK said:

when calculating my knock frequency (OEM piston diameter is 95.5mm and using the formula [(1800) / (3.1416 * dia)] = Frequency) 

1800 / (3.1416 * 95.5), 1800 / 300.02 = 5.9996, my Freq Channel should be set to 6khz??  It was defaulted at 4k to 10k hz.

I would start at 6Khz assuming they have a wideband sensor.

 

6 hours ago, BeallJK said:

Are there good threshold values to use for the 3.5 VQDE?  The G4 did have default values but I just wanted to double check.  

The default values are irrelevant, it will be different depending on your gain settings and many other factors.  You have to build this table to match the noise signature of your engine.  HPAcademy have a decent webinar on setting up G4+ knock control and car used for the example in the video is a 350Z so is probably relevant.  I think you only need a $20 for 1 month membership to view those webinars.

[BeallJK]

Thank you Adam - very good information and I appreciate your time.  

Yea - I'm looped in with HPA.  Got a VIP package a few years back and try to consume all their content.  I'll check out that webinar or course.   

[Adamw]

This is the one I had in mind:  https://www.hpacademy.com/previous-webinars/049-setting-up-knock-control-link-g4-vipec/