Re: New Injectors - Rough cold start/ Idle
For the tenth time, going lean is a function of the boost reducing the EFFECTIVE rail pressure. Raising the rail pressure solves the issue and I worked to develop a boost regulator that provides a fuel regulator pressure signal (compensation port) related to the manifold boost. As the boost goes up, the regulator signal and therefore the rail increases, but its regulated and not a one to one curve. I tied my boost to the fuel regulators boost port and when I was over 21# boost my fuel / air ratio fell to 8:1, obviously stock injectors can flood the engine if the rail pressure is adjusted.
Rob was selling the kits that resulted from this boost - regulator design and compensates for higher than stock boost. As you add air ( boost) the fuel demand increases, all the while the boost is pushing against the injector and increasingly reducing the fuel pressure DIFFERENTIAL on the injector, starving the engine.
When starting the engine with the throttle SHUT the engine will SUCK fuel out of the injector EVEN WITH THE FUEL PUMP NOT RUNNING,and keep running. WHY because the 20" (-10 PSIG) of manifold vacuum is enough to draw fuel thru the injector because of the pressure difference across the injector. Bigger injectors only reduce some of the restriction to "aid " fuel delivery. Raise your rail pressure to 60 # or so and youll see lower F/A readings.
Woody