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# Lambda Target Vs Different manifold pressures.

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Hi, I am using a Dta Ecu in the Uk but I'm struggling when it comes to the Target AFR's.

My Ecu is set up for Alpha N (Tps vs RPM) but with manifold pressure compensations for example 30kpa equates to 70% less fuel. The map compensation is a 3D table with Manifold pressure vs RPM and the ecu is Time based and not VE

Now this is all well and good except that you could be in a single cell with different manifold pressures. The problem arises when you want a different afr target because If for instance we was in cell 6%, 2000Rpm and we went from 70kpa to 100kpa and we wanted a different lambda target, the map compensations will compensate for the different pressure but theoretically will keep us at the same AFR at 100kpa. Now we have a Lambda target map but that is only in operation when closed loop Lambda Is on. I've commonly seen it that you could be in one cell @80kpa and then @120kpa in the same cell.

The ecu is quite basic and you can't just add another 3d table etc. I have only the two tables and the lambda target table when the closed loop is enabled. There is also air temp, water temp, start engine compensations etc too.

What would be the best option here?

Many thanks

Cant you do this:

There is that option and loose alpha N all together.

I liked the idea of alpha N when I started the mapping. Theres a safety aspect to it that if your waste gate fucked up and you ran higher boost then your suppose to at least fuel will correct to a sense. I have thought about using the map compensation table as a joint Lambda and map compensation table. For example If 100kpa was lambda 1 0% fuel change. Now if 100kpa was Lambda 0.92 Keeping a Lambda 1 reference in the compensation table @ 100kpa we apply an 8% fuel change. I have also made a formula to calculate other kpa area's. For example @ 120kpa with a lambda 0.86 Target there is a 14% difference from Lambda 1 so our usual 20% fuel increment changes to 36.8%. I wanted to get a second opinion on doing it that way as a joint Lambda/map compensation table.

What's wrong with overboost cutout? I think you are over complicating it what Adam suggested should work fine.