Ok I have Ford SVO 24 lb injectors. They enabled me to still acheive an optimal 960mV on my o2 readings with my 9psi pully. But after putting the 12-14 psi pully on my car its on the lean side with the FMU maxed out.

Ok now I have a couple options.

Purchase larger injectors. This is going to be nessassary later anyway as the 24's wont support much above what I'm already running even at 75psi of fuel pressure.

But I know a fer Vortec guys that "tune" thier FMU's with these discs that go inside the FMU. Apparantly these discs change the FMU behavior in some way. What exactly do they do and do ATI FMU's use the same discs that can be chaged to differant sizes?

I would liek to know so I can get my car more dialed in.

 

Oh and BTW. Dont tell me using my o2 sensor reading is inacurate and I should get a wideband o2 to read my exhaust.

I know this and I will upgrade my MAP sensor and o2 sensor later when I have the money.

ANd the injectors I was thinking of using next are Ford SVO 34 or 36 lb/hr injectors. I like the ford injectors they cost alot less then anything else and they perform great!

 

You could also add a superfueler.

Go here and check it out.


http://www.carrollsupercharging.com/

 

If you look on the vacuum line that leads into the FMU, there is a small white vacuum adapter. If you pull this off and look at it, you will see a small brass restrictor in this. Maybe you could modify this so the FMU will see more or less vaccum, which in turn will give you more or less fuel?

Just an idea

Matt

 

No i saw that vaccum conector and i took it off. My FMU was acting erratic with it on there.

i'm talking about INSIDE the FMU there are some sort of disk that you change with differant size ones that change the rate the FMU closes or something like. Its supposed to be a fairly commen tuning procedure with FMU's. Why does no one know what I'm talking about?

 

Why not just call the SC vendor. The guys at ATI are very friendly and helpful to me.

Seems like a basic question for them.

 

The discs change the ratio in which the FMU adds fuel. I think they come in 4, 6, 8 and 12 increments. That means that for every pound of boost it adds 4, 6, 8, and 12 pounds of fuel pressure.

 

hmmm. Ok so it changes the curve at which the FMU boosts fuel rail pressure.

So if i needed all out more fuel at redline then I'm going to need bigger injectors.

Oh well I'll still look into it for getting my A/F curve more dead on without having to go FMUless and use a custom chip with huge injectors.

 

some people with TPI's have gone to 30# and claim no drivability probs, and yet others needed chips to make this work. just like the vortech FMU's, ATI's can get higher ratio calibration kits. BTW, 75 PSI seems low to me as a max boost fuel pressure. I usually see 85 to 100 in cars that make over 9 psi. is your in tank pump dead or dying? try disconnecting the power to the AUX pump and see how the pressure runs (for function testing purposes only!)

 

I dont have any extra gauges in my car yet.

I dont even know what my engine is seeing as far as boost goes. But last time i checked my peak fuel pressure was with the larger pully. So I dunno now.