Gallery: Everything You Need to Know About The All-New Holley Sniper EFI 2

The greatest sluggers of our national pastime hit a home run once every 10 to 11 at-bats, which is quite a feat. However, if Holley Performance were a major leaguer, its home run percentage would be 100%. Holley hits home run after home run with every new product it develops. The latest big fly from Holley is an updated Sniper EFI system named Sniper EFI 2.

Above: The Holley Sniper EFI 2 system throttle body is an entirely new design incorporating the latest electronics technology. The Sniper 2 has two AN fittings. One or both may be utilized depending on the system (return or return-less). 

The Holley Sniper EFI 2 system is a new ground-up design to replace a carburetor and provides significant engine performance, fuel efficiency, and drivability benefits. The Sniper Ecosystem has multiple options for the best all-around package for each vehicle application based on engine, transmission, desired usage, etc.

The Sniper 2 has a user-friendly installation with the setup wizard, ignition and fuel system controls, monitoring displays, and additional accessories, making it the perfect choice for Mopar hot-rodders, classic car enthusiasts, and off-roaders.

Above Left: The Holley Quick Start manual provides in-depth information about its throttle linkage layout. There is even a provision for the Chrysler kick-down linkage. Above Right: The Sniper has multiple vacuum ports to meet the needs of every Chrysler engine.

The Sniper 2’s electronics comprise a Next Generation electronic control unit (ECU) with an upgraded radio frequency interference (RFI) resistance. The ECU incorporates a non-contact throttle position sensor (TPS), and the wiring harness has been updated to feature connectivity to a HyperSpark distributor.

Holley redesigned the throttle body with an internal fuel crossover, updated injector connectors, revised the four throttle blades and the two throttle blade shafts, and re-engineered the throttle cable and transmission kick-down bell crank assembly’s design. The throttle body has two finish options: a tumble-polished (shiny silver appearance) or a black powder-coated finish.

Above: The Sniper 2 throttle bodies come in a polished or black powder-coated finish. Regardless of the finish, both offer the same performance. 

There are three interface options for the Sniper 2:

A full-color, 3.5-inch hand-held display, like the first-generation Sniper

A full-color, 5-inch display with a GPS speedometer, three different views, and a windshield mount

A Bluetooth-capable module with iOS or Android smartphone connectivity. The Sniper 2 setup, tuning changes, gauge display, data logging, and tune storage are stored on the phone for easy retrieval. The Sniper 2 app also provides contact with Holley tech service.

Above Left: The Sniper 2 throttle body has reworked throttle blades and shafts. The new design provides increased airflow. Above Right: The throttle body has cast internal passage to allow the fuel to flow from one “float bowl” to the other to supply all four injectors with gasoline. 

Additional options include a standard harness or a power distribution module (PDM), which reduces the system’s wiring complexity. The master fuel kit has an inline fuel pump with filtration and is a return-style system; there are also return or return-less drop-in fuel pump options. Holley has fuel tanks designed explicitly for most muscle car era vehicles that can accept the pump, yet the tank fits into the factory location.

For ignition timing, not only does the HyperSpark distributor plug into the Sniper 2 harness, but all the Hyperspark components, which include the ignition module and coil, operate with the Sniper 2. Furthermore, for those with 4-speed automatic transmissions, the Sniper 2 Standalone Transmission Controller manages the shift characteristics of the transmission for maximum performance and drivability.

Above Left: One of the many Sniper 2 options includes the 3.5-inch full-color handheld display and an external fuel pump (part no. 550-510-3XK). Above Right: Another option is an in-tank fuel pump design with the same 3.5-inch display (part no. 550-511-3XR). 

An abbreviated overview of the Sniper EFI 2 installation follows. Before installing the Sniper EFI 2 system, the engine must be at its best possible tune. Before the swap, proper cylinder pressure and leak-down tests must be performed, ignition timing must be checked, and valve lash adjustments may be required. Holley suggests replacing the spark plugs and wires.

Above Left: To ease the wiring concerns with the Sniper 2, Holley developed a power distribution module (PDM). There are Sniper 2 options that provide a PDM and a different harness from the non-PDM units (part no. 550-510-3PK). Above Right: The PDM systems work with external and internal fuel pumps and return and return-less fuel systems (part no. 550-510-3PR). 

Before removing any parts from the engine, read and understand the Holley Quick Start manual. Step one of the installation requires locating a clean, switched 12-volt ” hot ” source in the run and cranking positions. Next, remove all the vacuum lines from the carburetor (label as necessary). Remove the carburetor after disconnecting the fuel line, throttle cable, kick-down linkage, choke wiring, and other components.

Install the new throttle body, and reinstall the throttle cable, kick-down linkage, vacuum lines, and other accessories as needed. The fuel lines, filters, and regulator must be appropriately located and routed from the gas tank to the throttle body. Holley has several options for the fuel pump location and plenty of color diagrams to assist with the installation order.

Above: The basic system’s wiring consists of five essential wires. There is a power wire for the pump, two wires to the battery, a switched 12-volt source, and an RPM signal. 

Depending upon the exhaust, use an existing oxygen sensor bung, weld one into the exhaust, or use a clamp-on style bung (included with the kit). In all cases, the oxygen sensor must be located before the catalytic converter and pointed downward into the pipe at a minimum of a 10° angle. Place the bung at least ten inches downstream from where the cylinder pipes merge and 18 inches before the pipe exit.

With the oxygen sensor installed, connect its wiring connector to the throttle body wiring harness. Locate the coolant temperature sensor (CTS) into the intake manifold or cylinder head, and like the oxygen sensor, attach the harness to the CTS. Follow the Holley manual to complete the installation and routing of the wiring harness.

Above: Although the complexity of the system’s wiring has increased, Holley provides clear instructions on how to wire up all the components, which include the optional HyperSpark distributor, coil, ignition controller, and additional wiring for an RPM reference, grounds, and 12-volt outputs. 

Due to the expansive options for ignition timing, it is best to contact the service techs at Holley for help with a specific application. The Sniper 2 provides complete ignition timing control when used with a HyperSpark distributor. However, it can be noted that the Sniper 2 works with points, High Energy Ignition (HEI), Capacitive Discharge (CD), and many other ignitions, but the Sniper 2 does not provide any timing control for them.

Above: The PDM has electrical color-coded electrical pins to wire the Sniper 2 system. Due to the centralized location and the color codes with a numbering system, wiring the Sniper 2 is a snap. 

The software setup is quickly completed by following the setup wizard. Once completed, the vehicle is ready to be started. The system will begin learning when the engine temperature reaches 160°F. Placing the automatic transmission in drive or reverse and turning on and off the air conditioning (if equipped) will load the engine, allowing for additional software learning.

Above Left: The display interface options include a 3.5-inch color display, a 5-inch color display, or Bluetooth Sniper 2 app that runs on a cell phone. Above Right: The Sniper 2 can be easily updated and monitored regardless of the interface selected. 

Light throttle application and moderate-speed driving will continue the learning process. More aggressive, even wide-open throttle applications will enhance fuel trim (and ignition timing) management. Once the close loop compensation fuel trim is near 0% in all driving conditions, the software has completed its learning process. Upon completion of the test drive, it is imperative to adjust the correction parameters to limit the ECU’s ability to make “wild” changes due to mechanical failures. Lastly, save the calibration with a unique name to access it later.

Above: Holley sells all the pieces to complete the entire fuel and ignition systems for a flawless upgraded electronic operation of a previously carbureted vehicle. 

A review of the key features and capabilities of the Holley Sniper 2 EFI system includes:

Self-learning technology – The Sniper EFI 2 system can tune itself, making it easier for users to install and set up without requiring extensive tuning knowledge.

Wideband oxygen sensor compatibility – The system includes a wideband oxygen sensor allowing real-time monitoring and precise fuel delivery adjustments.

Advanced fuel control – The system can manage various engine configurations, including naturally aspirated, forced induction (turbocharged or supercharged), and nitrous applications.

Holley EFI software – The Sniper 2 system is typically compatible with the Holley EFI software, providing additional tuning options and data logging capabilities.

Smartphone connectivity – Options allow for some Sniper 2 EFI system versions to use Bluetooth connectivity, allowing users to monitor and adjust parameters using a smartphone.

EFI-friendly ignition control – Additional options allow some Sniper 2 models to integrate with HyperSpark ignition control systems, providing a comprehensive engine management solution.

Each vehicle application is different, so working with the Holley representatives may be necessary to ease the selection process. With a finely tuned Sniper EFI 2 system, the vehicle’s drivability will increase, and the driver’s enjoyment will be equally enhanced.

Fuel-inlet-and-outlet TB-throttle-linkage-overview Vacuum-overview Throttle-Bodies Bottom-Throttle-Body Throttle-Linkage 550-510-3XK_01 550-511-3XR_01 550-510-3PK_01 550-510-3PR_01 Basic-Wiring-Sniper-EFI-2 Power Distribution Module Sniper-EFI-2-no-PDM Interface Interface-overview Ecosystem

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Chris Holley

Technical Contributor Chris has been a college professor for 25 years; at Pennsylvania College of Technology in Williamsport, PA. for the last 20 years. Chris instructs automotive classes in HVAC, electrical/electronics, and high-performance, including using a chassis dyno, flow benches, and various machining equipment. Recently, he added a vintage vehicle upholstery class to his teaching assignments. Chris owns a '67 Dart, a '75 Dart, a '06 Charger, and a '12 Cummins turbo diesel Ram, and he is a multi-time track champion (drag racing) with his '69 340 Dart, which he has owned for 34 years.

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