The Holley Sniper EFI 2 is an electronic fuel injection system designed for various engine types, including Chevrolet, Ford, and Chrysler small and big block engines, as well as marine applications. Installation involves connecting the throttle body, wiring the ECU, and installing the fuel pump and filters. Configuration and tuning are performed using a handheld device and associated software. Proper installation and configuration are critical for optimal system performance.
Supported Engine Types
The Holley Sniper EFI 2 system is compatible with a range of engine configurations. Supported engines include:
- Chevy Small Block: 327, 350, 355, 383, 396, 400, 427 (Builders Series), PS454 (builders series)
- Chevy Big Block: BP454, 496, 502, 540 (N/A), 572 (N/A), 598 (Builders Series), 632
- Ford Small Block: 302, 347, 408, 427 (builders series)
- Chrysler Small Block: BPC4082CTC (N/A), BPC4085CTC (N/A)
- Marine: 355 (N/A), 383 (N/A), 540 (N/A), 632 (N/A)
Distributor Installation and Configuration
Distributor installation requires careful attention to detail. The drive shaft must mesh correctly, and the distributor must seat fully. The 10-pin distributor connector must be connected to the Holley #558-493 adapter harness. For installations utilizing the 558-493 harness, completion of the harness installation is a prerequisite.
For engines with clockwise rotor rotation, the distributor housing should be turned clockwise until the Crank LED turns OFF. The rotor contact should be pointed at the housing during this process. After installing the cap, plug wires should be connected based on the engine’s firing order and rotor rotation. Reconnection of the coil power and ground connection is also necessary. Holley provides video resources for setting up the Sniper EFI with a Holley Dual Sync Distributor.
Distributor lockout procedures involve removing the rotor and advance components, including springs, weights, lock nut, and the advance stop bushing. Shims may be required during installation; if none are needed, one shim should be used beneath the washer of the Lock-Out Hold Down Screw. An adjustable rotor (MSD PN 84211 or PN 8421) may be installed depending on the application. The 2-wire connector on the distributor connects to the matching connector on the Sniper EFI power harness.
Wiring Overview
The Sniper EFI throttle body features pre-wired sensors for simplified installation. The ECU wiring requires connecting the main ECU power and ground directly to the battery after all other wiring is completed.
Wiring configurations vary depending on the ignition system. For stock type mechanical advance distributors with stock inductive ignition coils, the yellow wire marked “Coil-” functions as an RPM input. When using an aftermarket Capacitive Discharge (CD) ignition system (such as MSD or Accel), connection to the “Tach Out” is required, utilizing the Ignition Adapter / Purple Wire included with the main power harness. Holley recommends using a Holley Dual Sync distributor when utilizing timing control, although the Sniper EFI can accept a 1x per fire hall effect signal from other devices, with compatibility verification remaining the responsibility of the user. Video resources are available for setting up the Sniper EFI with a CD ignition box.
Holley suggests completing the engine run-in process without timing control initially, adding timing control as a secondary step to simplify troubleshooting.
Fuel System Installation
Installation of the fuel pump and filters is a critical step. The fuel pump must be mounted lower than the lowest point of the fuel tank and positioned as close to the tank as possible. Proper fuel tank venting is also essential.
If drilling into the fuel tank (rather than utilizing the sending unit), Holley recommends professional tank cleaning. If professional cleaning is not performed, the tank should be completely drained, dried, and filled with water before drilling. Fuel line installation involves connections using hose clamps and AN hose ends, as noted in the documentation.
Handheld Navigation and Data Logging
The Sniper EFI system utilizes a 3.5” handheld device with a touch screen display for navigation and adjustments. All navigation is performed by touching icons or buttons on the screen.
Data logging is possible using the handheld device. To initiate data logging, the “Start Log” option is selected. To stop data logging, the “Stop Log” option is selected. Data logs can be transferred to a computer for analysis using the Sniper EFI software.
Software Configuration and File Transfers
Calibration can be loaded into the Sniper EFI ECU from an SD card or directly from the computer using the Sniper EFI software. To load a configuration from an SD card, the configuration file (in the Saved GCF folder) is placed in the Sniper EFI Config File Folder (typically located in Documents > Holley > Sniper > Config Files). The software can then open the configuration file. Calibration can be viewed and modified within the software and saved back to the SD card or the Config Files folder. A copy of the tune must be placed on the SD card for transfer to the Sniper EFI via the handheld device.
Safety Precautions
The documentation includes a warning regarding the use of leaded fuel, which can degrade the oxygen sensor and require periodic replacement. Additionally, the documentation highlights the importance of selecting fuel pump and line components designed for high-pressure applications, particularly for higher horsepower engines.
Wiring Modifications
If wiring needs to be modified, the end of the wire should be cut to remove any bare copper. Adhesive heat shrink tubing should be used to insulate the connection, and a heat source (heat gun) should be used to shrink the tubing.
Parts Identification
The system includes various components, including an oxygen sensor (Bosch Wide Band 554-155) which requires a 3/4” hole for mounting. Proper mounting procedure is critical for system performance. The documentation also notes compatibility with draw-through supercharger applications, requiring conversion of the throttle body to read manifold pressure from a remote source.
Warranty Information
Failure of any single component does not constitute a warranty claim for the entire system. Individual service items are available for replacement. For warranty clarification or assistance, Holley Technical Service can be contacted at 1 (270) 781-9741.
Conclusion
The Holley Sniper EFI 2 system offers a comprehensive electronic fuel injection solution for a variety of engine types. Successful installation and configuration require careful attention to detail, adherence to the provided instructions, and utilization of the available resources, including video tutorials. Proper wiring, fuel system installation, and software configuration are essential for optimal performance and reliability.