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Mapping a maf based ecu

Road Tuning

Discussion and questions related to the course Road Tuning

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Hi André, i was wondering how you approach to tuning a maf based ecu such as a power fc.

You have only the correction map wich you can alter so you have no realy clue how much fuel you delivering to te engine. And what about the load axis, how can you compare this to a map based ecu.

What i also was wondering about is where in de map/load axis can you see the boosted reagions, i know this is in the bottom of the map but is there a rule to decide from wich load point your in the boosted region or is it simply try and error ?

Kind regards

Not Andre, but I have some experience with Nistune using AFM's

One thing I didnt like is eactly like you say... The load axis is not really anything you can relate to normally... most likely grams per second on your ecu, On Nistune it was simply "TP" (theoretical pulse width) which is in no clear relation to anything in the real world and quite arbitrary.

So yeh its basically trail and error... rely alot on datalogs logging load, Boost, RPM, AFR.

You dont need to know how many ms you are actually injecting, just worry about the AFR's.

It's been many years since I tuned a Power FC now so forgive my foggy memory. The load axis in the Power FC for a MAF input is a raw value that relates to the calculated MAF output rather than MAP. This means you can't directly relate the load value to a boost pressure but this doesn't really matter. You simply want to use the map tracer function to see where you're running in the map and this will guide you on exactly where to make changes.

With the L-Jetro models that use a MAF sensor, you can also manipulate the MAF calibration curve.

Maybe a kind of dumb questions but what are the benifits off rescaling the maf curve

No such thing as a dumb question!

Rescaling the MAF curve to correct for any errors means the ECU knows accurately how much air is entering the engine. This means that the ECU can achieve target air fuel ratios more accurately and gives you less work to do correcting the fuel delivery. If the MAF calibration is accurate then the tuning becomes much faster and easier.

How do you go to the proces of rescaling the maf curve?

This is covered in detail in the reflashing course. The process involves monitoring the AFR the ECU is commanding and the measured AFR and calculating an error. The error is then applied to that point in the MAF curve to correct it.