Forum » Link G4 Plus Software Tutorial » change to larger injectors G4+

change to larger injectors G4+

Link G4 Plus Software Tutorial

Discussion and questions related to the course Link G4 Software Tutorial


Page 1
Author
71 Views

is it possible to change in G4+ to larger injectors just with changing the injector datas without touching the fuel map ?

I received this same question from Thomas via our tech support email so Im going to paste a copy of my reply here for anyone else curious.

"If you are using the modelled fuel equation then yes you can just change the injector flow rate setting in the software. If you are using "traditional" fuel equation then you would just use the "master fuel trim" to scale the fuel pulsewidth by the inverse of the injector flow increase. For instance say you increased the injector size by 2X (say 500cc up to 1000cc), then you need to decrease the pulsewidth by 1/2. So put -50% in the Master fuel trim setting.

Having said that, in both cases it is rarely that straightforward. Things like the injector dead times, quoted flow rate accuracy and non-linearity may have an influence so you will often need to tweak the tune a little after something as major as an injector change."

The pulsewidth will remain the same? Or this will have to change also apart from the master fuel trim?

The pulsewidth will remain the same? Or this will have to change also apart from the master fuel trim?

I assume you mean the fuel table numbers? In theory you would not need to adjust the fuel table numbers as the injector flow change is taken care of with the Master fuel trim but as I mentioned above it is usually not quite that simple, you will normally need to touch up the fuel table.

does it also have an effect if I change the "injector rated fuel pressure" ?

The rated fuel pressure will affect the tune also. The data the ECu is looking for is an injector flow at a specific pressure which is then compared to your actual differential fuel pressure. If you alter either injector flow or pressure then your tune will change.

As Adam has alluded to above, a properly tuned VE-based ECU will allow you to get up and running after an injector swap and you 'should' be in the ball park. I've yet to see any aftermarket ECU that genuinely requires zero work in the VE map after this sort of swap though. You're almost certainly going to need a light work over and some small adjustments to get you back on point.