Fuel Adjustment Switch Box

[monaro308]

Here was a project i had to build a few years ago but never got around to doing it or seeing one work.
Might be a good project for a DIYfer....... i cooked this up tonight in Win XP paint

On the paper work it says:
A resistor switch box to be used for adjusting fuel delivery in a PFI V8.
The switch positions will determine voltage levels which will be read by two E.C.M. analogue inputs.

[adrian]

They work just fine, I built one a few years ago from obviously the same document you have.
I think you'll find it came around because of the Formula Holden/Brabham series that used the same ECU.
It appears that as they wern't allowed to change the ECU calibration this was the only way they could have some tunability of the A/F ratio.
Cheers

[VL400]

Is it true that the VL group A also made use of this feature with a small box thats set at the factory for each vehicle?

For those that are thinking of building this, the $5D code has the BPW trim modes so this will work. Later code bases dont have this feature. The formula holden bin, unsure of the Program ID (anyone know as the bin i have is set to 0xAA for engineering mode), has a MAP coefficient for the low RPM fuel trim.

[delcowizzid]

yeah the group A had something on the ecu pins for fuel trims for each bank i think didnt it i will delve into it further.i lost my formula holden bin in my pc reload but ill find a copy for some looksees i think it was $5d if i remember rightly.

[adrian]

The Formula Holden bin is very similar to the $5D but definately not the same.
From memory there were a few iterations but the code is basically $5D with some mods to the rev limiter and this "External BPW trim" function.
As it wasn't actually a production released calibration for a "production" car there was no inentifier ie $5D $12 etc

This function needs to be enabled at 000A bit 6 before you can use it

[Holden202T]

this might be a silly question .... but for someone like me ... what would be the advantage of this ? wouldn't i be better off just adjusting my VE tables ?

[adrian]

wouldn't i be better off just adjusting my VE tables ?

Sure would, I'd say this function was only there because they wern't allowed to adjust the VEs

[Holden202T]

yeah thats my thoughts too

[krawczuk]

hi, how about this ??

this is for a differant vehicle, but the voltage reg side is the bit u`d be using .
mark k

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