What F/P w/ emissions chip

[Royal-T-Ltd]

What F/P with an emissions chip? Do you run @ 45 or turn pressure down?

 

[ijames]

Whatever fuel pressure gets the idle and say 30-45 mph cruise BLM's closest to 128. If your injectors are smaller than about 55's then 43-45 is probably okay since I don't think most chipmakers change the injector constant from whatever they normally use for a street chip, based on the few emissions chips by others I've seen. A good cutoff is high impedance vs. low impedance injectors - if you have high impedance, stock type, injectors then this is true. There's no need to go lower because the commanded pulse widths are always well above the injector minimums and the higher pressure gives a better spray pattern. If you are running 72's or bigger then you need to drop the pressure down into the 30-35 psi range to keep the injector pulse width as long as possible to maximize ecm control of the fueling, and presumably your chipmaker knows that and has the inj const set appropriately but if not I still recommend dropping the pressure until the BLM's get up into the 140's. On my car going lower than 32 psi made the HC start to rise again, presumably because the spray pattern was falling apart so that's where I set things for emissions testing (30 and 34 were almost as good so it's not terribly finicky, and every car will be a little different anyway).

 

[ez at nova]

I ran 43.5 with my 009s