Honda K20A CAM Offset

[ChristianGrebe]

Hi,

I am not sure what to do with the CAM offset on my K20A.

The engine uses CAM1 as secondary trigger, CAM2 is unused as trigger. The variable cam is on CAM2. Which value is correct for the CAM offset of CAM2?

Here is a scope with deactivated VTC solenoid:

Thank you,

Christian

[Jadzwin_ECUMASTER]

As you can see on CAM2 there are tooth indexes at each scope line.
For CAM2 there is a trigger type tooth range.
So when you start to move the CAM#2 (you can do it with override DC in vvti config) you can check tooth index in the max cam advace/retard position.
Then you can enter tooth range eg. from 6 to 10. The CAM#2 offset should be 676 based on the scope.

[ChristianGrebe]

Whoa, not sure I can follow you there.

It looks like I have to setup a trigger for CAM2, right?
I have to define a tooth range window over the variable relative position of the cam by testing min and max position of cam?
Which tooth would I choose of the 4 teeth of the cam? The smallest?
Would the cam offset be the angle of the chosen tooth?

[Jadzwin_ECUMASTER]

in general yes. select the tooth from the scope above with the primary tooth index 9.
the selected tooth duirng cam movement cannot pass the n+1 tooth.
if you start to play with that you will understand

[ChristianGrebe]

I think I get it but no time to test on the engine for a few days.

Here’s my understanding:

1. Set Triggers - CAM 2 - Pattern to Primary teeth window
2. Triggers - CAM 2 - Crank tooth min and Crank tooth max define a trigger window for the primary trigger between which teeth the edge of the CAM 2 trigger is to be expected.
3. The angle of this CAM 2 trigger edge is then the VVT CAM 2 CAM offset for 0 ° advance/retard.
4. I could choose any of the (in my case) four CAM 2 trigger teeth as reference for the trigger window above.

Correct?

[Jadzwin_ECUMASTER]

@ChristianGrebe

s - CAM 2 - Crank tooth min and Crank tooth max define a trigger window for the primary

Yes. But be careful about tooth with the angle 316. It can pass the additional tooth if it moves right

[ChristianGrebe]

I set the CAM 2 Crank tooth min/max to 8/11 for a CAM 2 offset of 676 ° and it works fine.

Thank you!

[ChristianGrebe]

There is a strange behavior of the CAM 2 valve DC value.

Here are my CAM 2 parameters:

Here are my CAM 2 PID parameters:

Here is the graph:

Sometime the DC drops to 2 % for no particular reason, although a min DC of 20 % is set in the PID parameters.

[Jadzwin_ECUMASTER]

i think the rpm drops under min rpm and vvti disable the output (2%)
i will take a look at the code, maybe it should be clamped to min DC

[ChristianGrebe]

You are right. RPM does drop below CAM 2 parameters - Min RPM of 700. I think Min RPM should be set to have proper oil pressure?

Just to confirm: CAM 2 parameters - Start delay is active after the ECU leaves the cranking state?

[Jadzwin_ECUMASTER]

Yes Start delay starts to count when the EMU leaves the Cranking state