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Some basic questions

Introduction to Engine Tuning

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Hello.

I do not know if its allowed to ask questions before you take the course, but i hope that all forums are open to gold members.

I just looking on the free efi tuning video, and got some questions.

The VE map set the amount of fuel, and the AFR map do fine adjustments to the ve map? On OEM i think its called fuel trim, but fuel trim maybe not be used on aftermarket ecu?

I now that oem, at least was used to, get in open loop at full throttle, but on your tuning ideo, it looks like you are using the lanbda-senor at full throttle to? Maybe oem also do that these days with broad band lambda?

Should it not be possible to run the engine on only AFR-map? or is it to slow reactions?

Are there a lot off ve-maps that be used regarding of other factors, like temperature, air humidity, etc?

Looking forward to learn alot from you.

Thanks and best regards from Sweden

Hi Anders, sorry about the slow reply, it looks like your post got missed.

The VE map defines what amount of air is entering the cylinders. If the ECU knows this, and what size injectors are fitted, it can deliver the correct amount of fuel in order to achieve the AFR set in the AFR target map. So no, the AFR table is not a fuel trim table.

In the aftermarket you can usually define what operating conditions the ECU will operate in closed loop mode. Many lat model factory ECUs fitted with wideband lambda sensors also operate in closed loop continuously.

I assume you're asking if we could run the engine purely based off closed loop control? In which case the answer is no as we still need a base value for the EECU to work from in order to decide how much fuel to deliver in the first place.

How the ECU deals with temperature changes is dependent on the ECU. Often it's incorporated directly into the main fuel equation and compensated for automatically. On the other hand there may be a separate map for IAT correction.

I hope the above helps.