FlowForce ND2/ND3 High-Flow Injector Kit – Install & Tuning Guide

Thanks for picking up a set of FlowForce ND2/ND3 injectors! These are designed as a direct-fit upgrade for the 2.0L ND2/ND3 Skyactiv-G, with OEM-like drivability and extra fueling headroom. If any part of this process is confusing, or if you run into issues, please email us at team@goflowforce.com so we can help – and improve this documentation for others.

If you’re more of a “movie over book” person, we strongly recommend watching the install video:
Essential Fueling Upgrades for Your Boosted Miata – ND Injector & Fuel Pump Install .
That video walks through the full process on an ND chassis; this page focuses on the injector portion.

All FlowForce products are intended for off-road / competition use where applicable. Always follow local laws and the Mazda workshop manual for your car.

• +19% more flow vs. stock ND2/ND3 injectors
• OEM-like drivability – spray pattern & valving closely match stock for easy tuning
• Flow-tested & matched in Tennessee for consistent cylinder-to-cylinder fueling
• Direct fit for ND2 (2019–2022) and ND3 (2023+) 2.0L Skyactiv-G
• Supports pump gas and ethanol blends (with appropriate tune & fuel system capacity)

What’s included

1. 4x FlowForce ND2/ND3 high-flow injectors (matched set)
2. Pre-installed upper and lower O-rings
3. OEM-style injector clips / connectors
4. Install & tuning guide (this page)

1 . Kit Contents

2 . Vehicle Fitment

Works with both manual and automatic transmissions. A proper tune is required.

3 . Before You Start

1. Read this whole guide first

   • Review the video linked at the top.
   • Have the Mazda ND service manual handy for torque specs and exact bolt locations.

2. Basic tools

   • Metric socket set (8–14 mm), ratchet, and long extensions
   • 1/4" drive long extension and wobble adapter (for the lower intake manifold bolt)
   • Trim/panel tool or small flat screwdriver for plastic clips
   • Torque wrench (for reassembly per Mazda specs)
   • Shop rags and a small drain pan
   • Safety glasses and gloves

3. Safety & fuel pressure

   • Work only on a cool engine.
   • Disconnect the negative battery terminal before opening the fuel system.
   • Relieve fuel pressure per the service manual (typically by pulling the fuel pump fuse/relay and cranking briefly).
   • Keep all ignition sources (sparks, open flames, smoking) away from the work area.

4 . High-Level Install Overview

The ND uses gasoline direct injection. The injectors live in the cylinder head under the intake manifold, fed by a high-pressure fuel rail. You’ll remove the intake manifold, remove the rail and stock injectors, install the FlowForce injectors, and then reassemble everything.

The video link at the top shows these steps visually; follow it alongside this checklist.

1. Prep & access

   • Disconnect battery and relieve fuel pressure.
   • Remove the plastic engine cover.
   • Remove intake tubing / airbox as needed to access the throttle body and intake manifold bolts.
   • Remove any strut tower brace that blocks access.

2. Unplug sensors & hoses

   • Unplug the throttle body and any sensors attached to the intake manifold (MAP, etc.).
   • Disconnect PCV, EVAP, and vacuum lines from the manifold.
   • Label or photograph connectors and hoses so they go back in the right place.

3. Remove the intake manifold

   • Remove the visible upper bolts and nuts.
   • Use a long 1/4" extension with a wobble to reach the hidden lower intake manifold bolt (above the starter).
   • Carefully pull the manifold away from the head, unplugging any remaining connectors on the backside as needed.
   • Cover the intake ports with clean rags to keep debris out.

4. Remove the fuel rail & stock injectors

   • Clean around the fuel rail and injector area so dirt doesn’t fall into the ports.
   • Disconnect the high-pressure fuel line from the rail (use line-appropriate wrenches and follow the manual exactly).
   • Unplug all injector connectors and any short harnesses on the rail.
   • Remove the rail mounting bolts, then gently lift the rail away from the head.
   • Pull the stock injectors out of the head/rail, keeping track of any spacers or seals (these will not be reused).

5. Install FlowForce injectors

   • Inspect the new injectors and seals – make sure all O-rings are present and undamaged.
   • Lightly lubricate O-rings with clean engine oil or fuel-safe lube.
   • Install the injectors straight into the head or into the rail (depending on your preferred method), avoiding twisting or cocking them.
   • Reinstall the fuel rail with the FlowForce injectors seated in the head.
   • Reattach the high-pressure line and torque all fasteners to Mazda specs.
   • Reconnect the injector connectors until they click positively into place.

6. Reassemble the intake side

   • Remove rags from the intake ports.
   • Reinstall the intake manifold with new gaskets if required, and torque in the correct sequence.
   • Reconnect all sensors, hoses, and lines (throttle body, MAP/MAF, PCV, EVAP, etc.).
   • Reinstall intake tubing / airbox and any strut brace.
   • Reinstall the engine cover.

5 . Priming, Leak Check & First Start

1. Prime the fuel system

   • Reinstall the fuel pump fuse/relay (if removed).
   • Reconnect the negative battery terminal.
   • Turn the ignition ON (without cranking) for 10–15 seconds, then OFF. Repeat 2–3 times to let the pump build pressure.

2. Check for leaks

   • With the ignition ON and engine off, inspect around each injector, the rail, and high-pressure line connection.
   • If you see or smell fuel, turn the ignition OFF immediately and fix the issue before starting the engine.

3. First start

   • Start the engine and let it idle. It may crank slightly longer on the first start – that’s normal.
   • Watch for misfires, check engine lights, or fuel smells.
   • Allow the engine to reach operating temperature before test driving.

6 . Tuning Quick-Start

These injectors are designed to behave like stock ND2/ND3 injectors with ~19% more flow. That makes tuning straightforward compared to “wild” aftermarket injectors, but a proper tune is still required.

Important: Once the injectors are installed, do not drive aggressively or add ethanol/boost until your tune has been updated for these injectors.

7 . Troubleshooting Quick Tips

Need help?
FlowForce Tech Support • support@goflowforce.com
Please include your order number, vehicle year (ND2 or ND3), transmission, full mod list, tuning platform, and a description of the issue.

Happy boosting!