VT running very lean? Help!!

[VSteve]

OK so I am trying to be thrifty and tune my own memcal to use with a intercooled raptor supercharger. Car is a VT and I am using BA XR6 turbo injectors which I believe are 28lb. Anyways I am using a L67 supercharged tune (CXWK) as a staring point and have adjusted the base injector rate to 259.72 to suit the new injectors. I haven't installed the supercharger yet but went for a drive with just the injectors, intercooler, piping and newly programmed memcal in place and found that above about 20% throttle the engine leans out to 17:1 or higher. Below 20% throttle its pretty normal AFRs at around 13-14:1. So I am wondering why is it leaning out so much? What have I done wrong/haven't done to make this work?? I have attached the tune and hope someone can tell me what is wrong with it and what I should change?

[delcowizzid]

every injector opens with different caracteristics just changeing the injector size doesnt make them work perfect theres lots of tables to tweak to get it back inline its easier to just fit the real L67 injectors really if its the first time tuning would make life way easier.

[yoda69]

Couple of quick questions.
What are you using to measure the AFR at 17:1?
Can you put up a datalog of the engine, there is an ADX on this forum to do so?

If it's happening around 20% throttle it could be going into lean cruise which command AFR's of around 17 in some areas.
This is where the log will help.

Thanks,
yoda69

[Holden202T]

no he said its lean above 20% throttle ....

i tend to agree with delcowizzid might be injector offset table is now out of whack or a power enrichment or something like that ....

but yeah really need to see a log to see whats happening when its lean.

[VSteve]

I am using a AEM wideband for the air fuel ratios. Where abouts would I find a ADX and info on logging? Also I have noticed that L67s run 8psi more fuel pressure so that might be something to look in to??

[delcowizzid]

vt NA should have the same fuel pressure as a vs L67 is it intercooled fit the maf after the cooler and after the BOV about a foot away from the throttlebody if its cooled and on the inlet of the charger youll have issues

[charlay86]

XR6Ts run 4bar fuel pressure to get those injectors to flow 28lb/hr.
What is your current fuel pressure?

[VSteve]

XR6Ts run 4bar fuel pressure to get those injectors to flow 28lb/hr.
What is your current fuel pressure?

Yes XR6Ts do run 4 bar fuel pressure but the 28lb/hr figure is measured at 3 bar like most injectors are. VTs have a 3.5bar fuel pressure reg so the injectors should flow about 30.5lb in a VT? Can anyone else confirm this?

[vn5000]

My gregorys efi manual says fuel press :
std - 270 - 310 kpa
s/charged - 290 - 410 kpa
As the press reg is connected to manifold vac / pressure, i suppose the more boost you run the higher the fuel press will be.
What is the max press your pump can acheive at high flow.

[charlay86]

Yeah the L67 has a 1:1 rising rate reg. Every kPa of boost gives an extra kPa of fuel pressure on top of the base pressure (which is 350kPa from memory)