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Hi,

I did listen to 4D Tuning Link G4 Plus webinar.

I think very good way how to tune that kind of engines with main fuel map from TPS, ignition from MAP and second load from MAP.

As You mentioned double pressure double fuel, for example in Motec, should this table be configured like this?

and than tune engine by TPS and later make compensations in second load tables?

Thank You

In the Motec hundred series ECUs, my preference is to use the TPS as the load axis for the primary load table and use MAP for the second load axis. The MAP comp table needs to be set as you have shown (double MAP equals double fuel), but that on its own will only target the same lambda value throughout the range of manifold pressure. What we need is a way of targeting a different lambda as the boost increases and I do this using the second load table.

The way I do this is by assuming the target lambda is 1.00 everywhere. Then I use the secondary load table as a kind of 'open loop AFR' table to use Link terminology. This table requests a percentage change in fuel any time I don;t want to be at lambda 1.00. For example say at 200 kPa we want to run lambda 0.85. To achieve this we can calculate the required additional fuel as a percentage by dividing the 1.00 by 0.85. The result is 1.18 or 18%. So in the secondary load table we would enter 18% at 200 kPa. I just fill out the table using this method at each load point. You should find that the lambda then tracks your desired lambda target very accurately regardless of throttle position or manifold pressure.

I've attached a screen shot showing an example of how I have set up this secondary load table.

Attached Files

Thank You a lot, now everything is perfectly clear!

Let me know if you have any further questions once you start tuning.

So does this mean the MAP table is the one adding supplementary fuel to whatever fuel is added based on the TPS table?

@tapeneck - In essence yes, however there's a bit more to it.

The MAP compensation table should be set up as a very simple linear table which doubles fuel delivery when the MAP value is doubled. It should just be a 2D table vs MAP. This table serves to maintain a fixed AFR as MAP changes, however we almost certainly don't want the same AFR at 100 kPa as we want at 200 kPa. in order to vary our AFR as the MAP changes we need to use the AFR target table or alternatively if your ECU doesn't have an AFR target table, you could use a 4D table to add fuel to get to your new target.

@Andre -

Thanks for the answer buddy. Okay all this is abit advanced for me but I will understand it soon. I just watched webinar 163 on tuning and ITB and Turbo set up on Alpha n and I had some questions on that topic. I will open up a different thread to ask questions regarding that.

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