PCII

Fuel + ignition timing…like an override…adds a percentage before it gets to injectors


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PCIII

Injectors only


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PCIIIR

Fuel + ignition timing

Harley Electronic Fuel Injection


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EFI Advantages
The driving force behind Harley going to EFI is the ever-increasing emissions control dictates from the government reflecting concerns about the environment. Carburetors are already a thing of the past on many vehicles for this very reason. Harley, as usual, lags behind but make no mistake carburetors will be a thing of the past in the not too distant future. The precision of fuel delivery on EFI system lowers harmful emissions and as an extra bonus improves fuel economy. For the sophisticated, it can also do wonders for high-performance goals. Think about it! Carburetors are finicky and imprecise. They, by definition, cannot deliver the right amount of fuel and air for all rpm ranges never mind “load” requirements. EFI can deliver precise amounts of gas and air at any rpm and at any load.

EFI Is Faster
But the EFI Harley’s are slower than the carbureted ones. Yes, they were. Check out a V-Rod if you want to see what EFI is capable of in the speed department while meeting emissions dictates. Just imagine if the emissions restrictions were eliminated on this baby. The problem to address is the fixed spark maps on the stock Harley EFI systems.

Fixed Spark Maps Are the Problem
Spark maps are in the electronic control module or computer known as the “brain” in Harleyese. It tells the injectors when and how long to open. It also tells the spark plugs when to fire. Having the ability to remove the “fixed” part and adjust these settings at will for every rpm and load setting via laptop computer opens a new era in Harley hi-performance that will eclipse dinosaur carburetor technology. Some mechanics are afraid of new technology because they are the best at the old technology. Unless they constantly learn they fall by the wayside.

Cold Starting is a Breeze
Easy starting is another big EFI feature especially in adverse climatic conditions like cold weather starts. While adding numerous parts unfamiliar with a carbureted system like fuel pumps, solenoids and sensors, EFI also eliminates the need for a cold start enrichment device, (choke), cable and a gas petcock. The bottom line is that it does add many more parts than it eliminates. However more importantly, accurate fuel delivery under differing but specific engine loads and operating conditions is the big plus over the relatively wasteful carburetor.

EFI Primer
A carburetor draws and mixes fuel and air via vacuum, manifold pressure differentials and venturi air speed. The venturi is the throat of the air/fuel delivery system whether it is carbureted or fuel injected. Electronic Fuel Injection has fuel delivered under pressure by a pump to gizmos called injectors. Injectors inject fuel as a pressurized spray. There are two separate fuel injectors in a Harley engine, one for each cylinder. The longer an ejector nozzle is held open determines the amount of fuel sprayed onto the back of the intake valve just as it opens and into their respective cylinder. The time the injector valve is open is called the injection “pulse width”. The pulse width gets longer when more fuel is required. This “on time” or “width” is measured in milliseconds. A millisecond means one thousandths of a second. This of course is all determined by a computer whose processor receives sensor information and has the ability to change pulse width over a hundred times per second. EFI is a long way from a carburetor when information dictating fuel spray is processed in les