# Load axis - TPS BAP corr.

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How does the barometric correction get applied to a TPS based load axis?

I'm thinking of reverting to a TPS based load axis but I would like to understand how this standardÂ correction is applied before I make the change. I was planning to introduce a MAP based correction by means ofÂ a MGP based 4D map, but I don't want toÂ inadvertantly add in the same correction twice if its already in there.

Does the BaroÂ correctionÂ apply a 1% change to the value in the base fuel mapÂ forÂ each kPa above/below standardÂ atmospheric condition?

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On a similar note, is it possible to obtain an electronic model that shows how the ECU works and calculates all of its parameters?

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Thanks,

Â

James

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Hi James,

Have a read of this PCLink Help > G4 ECU Tuning Functions > Fuel > Fuel Setup > Â Fuel Equation

It explains which setup options use barometric compensation and which do not.

I think you would be best to have your Fuel Equation set to Load = BAP, set the load axis of your main fuel table to TPS and then set your 4D load axis to MAP.

We do not have an electronic model of the ECU.

Cheers,

Scott.

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Thanks Scott,

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I've had a look at that but it would appear to beÂ basedÂ onÂ the G4 ECU and I don't think the G3 is the same. Is that correct?

The way I read it,Â the G3 options for a TPS-based Y-axis areÂ equivalent toÂ Load = MAP or Load = BAP/MAP/X-over in G4 terminology.

If I set my G3 to "Throttle position - BAP correction"Â and then tune the car, will I get a map that is correct for ambient pressure but not referenced to manifold pressure at any point? If so then it seems OK and I can add my manifold pressure adjustment via a 4D table. That adjustment will then be from 0-3 bar Absolute.

I'm still slightly concernedÂ however that the values I tune into my fuel table will already allow for changing manifold pressures. Can you confirm if that is the case?

Â

James

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Hi again James,

Apologies, I missed that it was a G3 ECU you have. I have loaded up the PCLink 3.4 and looked at the options and help, and also spoken to the engineer who did some work on that version.

The consensus is that you would want to set your load axis to Throttle Position - BAP Correction and your 4D table to MAP. This should give you your barometric compensation only once.

Regards,

Scott

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OK thanks,Â  I'll give it a go.

Â

James

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