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Hello,

In AVCS target table default setting of Y axis is TP (main).

Don't you think more resonable to use MAP instead?

However, if I chose MAP, there is lack of cells (I mean  that there are only 11, that is insufficient for acuracy)

How to do the best?

 

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No, I used to think the same - it would be easier to use MAP for the VVT load axis as then it has more relationship to your VE table and it would then be easier to account for the change in VE due to cam position.

But, as I have been doing more VVT recently I have learnt that theory is not true and it is better to use TP for the VVT load axis.  The reason is that cam timing significantly affects the MAP, so if you have MAP as an axis on your VVT table, then in some situations you get the cam becoming unstable bouncing backwards and forwards because it is both affecting MAP and controlled by MAP.

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On 4/22/2020 at 11:50 PM, Adamw said:

No, I used to think the same - it would be easier to use MAP for the VVT load axis as then it has more relationship to your VE table and it would then be easier to account for the change in VE due to cam position.

But, as I have been doing more VVT recently I have learnt that theory is not true and it is better to use TP for the VVT load axis.  The reason is that cam timing significantly affects the MAP, so if you have MAP as an axis on your VVT table, then in some situations you get the cam becoming unstable bouncing backwards and forwards because it is both affecting MAP and controlled by MAP.

Hi Adam,

Do you think same for MIVEC to keep axis TP?

Best regards

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On 4/22/2020 at 5:50 PM, Adamw said:

No, I used to think the same - it would be easier to use MAP for the VVT load axis as then it has more relationship to your VE table and it would then be easier to account for the change in VE due to cam position.

But, as I have been doing more VVT recently I have learnt that theory is not true and it is better to use TP for the VVT load axis.  The reason is that cam timing significantly affects the MAP, so if you have MAP as an axis on your VVT table, then in some situations you get the cam becoming unstable bouncing backwards and forwards because it is both affecting MAP and controlled by MAP.

Interesting... I need to change mine back. I was struggling with some oddities using MAP. One issue I found is that cruising/idling/decel MAP values can kind of seem to overlap and blend so I was struggling to get the cams to advance when I really wanted them to. Using throttle position would help in that regard.

Although it seems that most intake cam timing on turbo cars is MAP pressure based because it's typically used for boost onset improvements. You'd have to be dependent on RPM only there unless you did some kind of TP vs MAP table but that may get really messy.

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