VEMS Community Forum

VEMS => Configuration => Topic started by: AVP on March 29, 2011, 07:25:19 AM

Title: Knock sensing
Post by: AVP on March 29, 2011, 07:25:19 AM
I noticed that on 1.1.88 there are a few add ons on the knock sensors. Anyone already figured out how they need to be setup on an audi 5cyl engine? Do they perform now?
Title: Re: Knock sensing
Post by: GintsK on March 29, 2011, 10:20:16 AM
Seems new knock sense do not work on 1.1.88. It works on non released 1.1.89.
I hope on 1.1.90

Knock_alternative itself looks very promising. In Russia guys use it for long while.

Blury part is knock sensor sequence:
QuoteKnock channel.
0 means sensor 1 for all cylinders
255 means sensor  2 for all cylinders.

If you need to combine the sensors-events it is more tricky:
0 comes from 00000000 binary
255 comes from 11111111 binary

So if you want to use sensors accordantly to cylinders (spark events) , then for example
10101010 (170) will switch sensor for every spark event.

1 at the  beginning belong to bottom cylinder in ignition output table (non used one if it is not 8cyl engine).
0 at  the end belong to top cylinder in same table (used always).

any desired combination except 11110000 (240) and 11110001 (241) can be used. These two disables knock.

Converting binary<-> decimal can be done by windows native calculator.

You can read it in different "language" in 1.1.26 description here:
http://www.vems.hu/wiki/index.php?page=GenBoard%2FUnderDevelopment%2FFirmwareChanges

Of course you have to be sure about hardware present inside ECU for second sensor.

Gints

Regarding knock alternative please read this wiki page. If you have questions, just ask.
http://www.vems.hu/wiki/index.php?page=MembersPage%2FAndrey%2FKnock

Gints
Title: Re: Knock sensing
Post by: BigD on March 29, 2011, 04:19:38 PM
So just to confirm, if I have the top 6 inputs going to cyl 5-3-6-2-4-1 (bottom up), and if I have ec18 pin 1 on cyl 1-3, and cyl 4-6 on pin 2, then 170 should work for me?

Also, I have 3.6 and they deleted knock 2 in favor of an analog input. I added a jumper from the other knock chip pin to pin 2. So when it says pin 1 = knock 1, that's the one that's used when a bit is 0? (in other words, in my case, bit 0 = cyl 1-3, bit 1 = cyl 4-6)
Title: Re: Knock sensing
Post by: GintsK on March 29, 2011, 04:27:21 PM
Yes, 170 seems correct in this case.
But double check knock input. Just jumper could be not enough: sometimes two 22kOhm resistors and one cap for input also missing.
Title: Re: Knock sensing
Post by: BigD on March 29, 2011, 04:39:40 PM
Thanks! What's the best way to verify it? Turn on logging and smack the engine? Would it log with the engine off?
Title: Re: Knock sensing
Post by: BigD on March 29, 2011, 04:53:22 PM
Can you tell me where to look for these components? I read the knock page but I'm not clear about where these resistors need to be...

http://www.vems.hu/wiki/index.php?page=GenBoard%2FManual%2FKnockSensor

I guess one needs to be next to r2? But where should the others be? I'm not sure what the diagonal position is.
Title: Re: Knock sensing
Post by: GintsK on March 29, 2011, 09:32:28 PM
I doesn't log with engine off. And it doesn't log also with engine running on 1.1.88  ;D Until you reach something like 8000rpms  ;D

You see diagonal pads for two SMD parts? Here should be soldered one resistor an one capacitor.
(http://www.vems.co.uk/VEMS/KnockChipCrystal.jpg)
Title: Re: Knock sensing
Post by: AVP on March 29, 2011, 09:39:41 PM
already by looking at the vems link, it looks quite complicated to me!

the thing though is that still on 1.1.88 the knock sensing does not work..

Gintis, for 2 knock sensors which number 1 sees cylinders 1,2 and 3 and knock sensor number 2 looking at cylinders 4 and 5, does that mean that the channell should be 21 as you have on your settings?

also to properly configure the knock sensors, does it mean that we should know the firing order of the cylinders so that the sensors can detect at the right time?
Title: Re: Knock sensing
Post by: GintsK on March 29, 2011, 10:07:14 PM
What is complicated?

21 decimal is same as 00010101 binary - seems incorrect.
h[2]  sensor
3        0     
5        1
4        1
2        0
1        0
x        0
x        0
x        0

so 00000110 is 6 decimal (3 entries on bottom has no sense for 5cyl engine - it can be 0 or 1 as well)
Title: Re: Knock sensing
Post by: mattias on March 29, 2011, 10:12:59 PM
For me personally, even if I can figure out how the system works - this stuff should be in a more "visual" dialog. I'll put that on the wishlist.
Title: Re: Knock sensing
Post by: BigD on March 30, 2011, 03:12:36 AM
Quote from: GintsK on March 29, 2011, 09:32:28 PM
I doesn't log with engine off. And it doesn't log also with engine running on 1.1.88  ;D Until you reach something like 8000rpms  ;D

You see diagonal pads for two SMD parts? Here should be soldered one resistor an one capacitor.
(http://www.vems.co.uk/VEMS/KnockChipCrystal.jpg)

Ok so I took the box apart, I do have the resistor next to R2, but the back side of the board looks just like above, just 4 solder blobs, no parts. So my knock 2 doesn't work?

I was digging through my logs, I've got logged values for all 6 cylinders, and even have some knock adjust during deceleration:

(http://i.imgur.com/jsqnL.png)
Title: Re: Knock sensing
Post by: GintsK on March 30, 2011, 07:26:58 AM
Then second sensor is simply disconnected from knock chip.

Before you looking at knock retard action, you have to adjust knock noise levels for each cylinder (you can try it juast for three front cylinders). I think best is about 1/4..1/3 of maximal 1012. It would be something like 30....80 at low rpms and 250....350 at full load. without knock of course.
Title: Re: Knock sensing
Post by: z0tya on March 30, 2011, 09:03:32 AM
Quote from: GintsK on March 30, 2011, 07:26:58 AM
Then second sensor is simply disconnected from knock chip.

Before you looking at knock retard action, you have to adjust knock noise levels for each cylinder (you can try it juast for three front cylinders). I think best is about 1/4..1/3 of maximal 1012. It would be something like 30....80 at low rpms and 250....350 at full load. without knock of course.

but need unofficial 1.1.89 for it? :)
Title: Re: Knock sensing
Post by: GintsK on March 30, 2011, 09:21:14 AM
I hadn't any knock noise with 1.1.88. May be BigD have!
Title: Re: Knock sensing
Post by: BigD on March 30, 2011, 12:57:10 PM
Quote from: GintsK on March 30, 2011, 07:26:58 AM
Then second sensor is simply disconnected from knock chip.

Before you looking at knock retard action, you have to adjust knock noise levels for each cylinder (you can try it juast for three front cylinders). I think best is about 1/4..1/3 of maximal 1012. It would be something like 30....80 at low rpms and 250....350 at full load. without knock of course.

How is it possible then that I have reasonable and consistent values logged for all 6 cylinders with an alternating knock sensing strategy (85)? I should be seeing nothing for every other cylinder...
Title: Re: Knock sensing
Post by: GintsK on March 30, 2011, 02:26:31 PM
Sorry? Have you 1.1.85 compiled with knock alternative?

In any case for >1.1.88 you must chose what to log in those separate channels: individual power or knock noise. There are drop-down menu for this choice. Might be it is individual power what you see in your logs???
Title: Re: Knock sensing
Post by: BigD on March 30, 2011, 02:31:16 PM
The log you see there is from 1.1.77. The fields are from Knock->Knock0..5. Knock 6-7 have nothing as expected. But 0-5 have reasonable values and the knock chan is 85, which should alternate between input 0 and 1. But if my 2nd input is disconnected, how is this possible?
Title: Re: Knock sensing
Post by: AVP on March 31, 2011, 08:21:45 AM
i hope knock sensing becomes usable and easily configurable, because that will close the gap of IAT ignition retard to ignition retard due to low octane in fuel. It seems that there are a lot of fuel stations out there that supply rotten fuel for 98 octane and VEMS has no way of knowing this other than the knock sensors. I believe that even those are not enough, especially when 1 is used for 2 or 3 cylinders, but at least now they are just sitting there doing nothing.
Title: Re: Knock sensing
Post by: GintsK on March 31, 2011, 08:26:43 AM
Quote from: BigD on March 30, 2011, 02:31:16 PM
The log you see there is from 1.1.77. The fields are from Knock->Knock0..5. Knock 6-7 have nothing as expected. But 0-5 have reasonable values and the knock chan is 85, which should alternate between input 0 and 1. But if my 2nd input is disconnected, how is this possible?
I think you do not see knock but individual power there.