E38?

[wildfan1976]

Plan going to boost reference fuel pressure from static fuel pressure. Besides maxing out injector flow rate I'm I going to have to retune my MAF and VVE tables? Its on a Pontiac G8 with a LSA.

[blindsquirrel]

'maxing out injector flow rate'? Why?

The Injector Flow Rate & Offset vs... tables need to be configured different, but unless you're changing the actual injectors you don't change the base flow rate.

[wildfan1976]

What I meant was with the G8 E38 the flow rate vs pressure maxes out at 63.5 lbs/hr. Ive seen some tunes with boost reference have the flow rate vs pressure all the same number in the flow rate column.

[wildfan1976]

What all needs to be changed?

[blindsquirrel]

If you do not change the injectors, you do not change the flow rate, other than taking the correct lb/hr and pasting that across the whole table, because adding the reference to the regulator eliminates the pressure delta slope - it's now always the same pressure delta all the time because anytime manifold pressure goes up rail pressure goes up too by the same amount. Same delta = same flow rate whether it's at minimum MAP in heavy decel/overrun or at max boost.

If you are changing injectors at the same time, and they are bigger than the 63.5 limit, then the tune has to be scaled.

These two things are not really related other than they're both about injectors.

(It might help if you could tell what injectors you have now, what injectors you're changing to, and what you're working on (I didn't think the G8 was a one-year-only thing where all of them were the same). You will never, ever get yelled at if you include a tune file and it turns out it's not needed to answer your questions. But if somebody would like to be able to give you specific, detailed advice and they can't because they can't see what you are working on...)

[wildfan1976]

Car runs amazing no issues at all. My fuel pressure drops about 10lbs under boost which is the same amount of boost it makes. Car never runs lean according to my wideband under full boost so maybe just leave it if its working fine?8-8-22 orginal trans tune.hpt

[eXo3901]

so maybe just leave it if its working fine?

If you DO NOT add a manifold referenced regulator.
-Yes.

If you DO add a manifold referenced regulator.
-No, you will need to change some injector tables, as mostly noted above.

[blindsquirrel]

Fuel pressure should not drop under load. At all. Is this still with the non-referenced/returnless setup?

If you've already changed the regulator, fuel pressure should RISE under load, as manifold pressure increases.

[wildfan1976]

Not changing injectors at all just thinking of changing to boost reference. I run deadhead to the rail with a regulator by the fuel tank. I need it because my return fuel is also the tank siphon for the split style tank of the G8. The fuel pressure drop is with the non referenced regulator.

[blindsquirrel]

Assuming all the injector data in your file is correct, these are the changes you'd need for the regulator change, and using a base pressure of 58psi at idle with the vacuum hose removed.
8-8-22 orginal trans tune - referenced.hpt

[wildfan1976]

Now with the change will I have to do some tweaking of my MAF and VVE tables?

[blindsquirrel]

Theoretically, if that's the fuel pressure it has and the injector data was correct before, no.

[blindsquirrel]

How do you guys all end up finding the same post? Is there like a bulletin board in the internet cafe you all work out of, with a list of easy targets to hit?

[schpenxel]

How do you guys all end up finding the same post? Is there like a bulletin board in the internet cafe you all work out of, with a list of easy targets to hit?

Probably