Precision Raceworks M3 / M4 / M340i / M440i (G8X / G2X) Stand-Alone AFS

OVERVIEW

The Precision Raceworks Stand-Alone AFS is a complete auxiliary fuel system for port injection on the G80 M3, G82 / G83 M4, G20 M340i and G22 / G23 / G26 M440i. It is the last piece of a port injection build, not a standalone upgrade.

Instead of sharing the factory supply, the AFS puts its own pump or pumps in the tank and runs dedicated AN6 lines to the port injection rail. The factory primary pump is PWM controlled and backs off around 5 bar, and the high-pressure pump control pushes fuel back into the low side, so a shared supply oscillates. A dedicated system holds steady pressure that scales 1:1 with boost, which lets you run smaller port injectors, reduces how hard the DI system has to correct and makes the car easier to tune.

Two flow ratings are offered here: AFS.425 with a single Walbro 450 and AFS.800 with dual Walbro 535 pumps. This version uses Precision Raceworks' hinged pump mounting arm.

SPECS

• AFS.425 (601-0281): single Walbro 450 (F90000274), 425 LPH at 3 bar
• AFS.800 (601-0285): dual Walbro 535 (F90000295), 800 LPH combined at 3 bar
• Billet aluminum top hat with 3 high-flow fuel ports
• Dedicated AFS pump(s) mounted in a slosh-resistant location, independent of the factory PWM-controlled primary pump
• Fully adjustable 1:1 boost-referenced billet fuel pressure regulator
• 10 micron USA-made microglass fuel filter, E85 rated
• AN6 smooth-bore PTFE feed and return lines with billet fittings
• Plug-and-play connectors inside and outside the top hat; configurable pump activation harness
• Works with stock or upgraded primary fuel pumps; all components 100% ethanol compatible

PARTS INCLUDED

• Complete stand-alone auxiliary fuel system for the flow rating selected: billet top hat, AFS pump(s) on the mounting arm, adjustable 1:1 billet regulator, 10 micron microglass filter, AN6 PTFE feed and return lines, billet fittings, plug-and-play connectors and the configurable pump activation harness

TECH RESOURCES

Required Extras

• A port injection kit with the fuel rail mounted above the intake manifold is required; the AFS feeds that rail and does nothing on its own: Precision Raceworks B58 Port Injection Kit (B58 cars) or Precision Raceworks S58 Port Injection Kit (S58 cars). Plate-style spacer port injection is not supported by the standard AFS kits; contact us before ordering for a plate-style setup.
• Precision Raceworks Solid State Relay Upgrade Kit — only if your tuner calls for solid state relays; one kit per AFS pump (AFS.425 needs one, AFS.800 needs two); sold separately (not stocked by Speed Logic).
• Precision Raceworks G-Series & MkV Supra PNP Harness for Billet Top Hat (201-0419 upper / 201-0386 lower / 622-0296 both) — optional plug-and-play adapter to the factory fuel pump wiring; sold separately (not stocked by Speed Logic).
• A tune that controls the port injection system and the AFS pump activation output, set up by your tuner.

Installation

• Stand-Alone AFS install guide, Revision 02 (PDF): AFS Installation Guide Rev 02
• G8X / G2X AFS install video (Precision Raceworks): youtu.be/HpgfUxx2-Ck
• Hinged-arm AFS install video (Precision Raceworks): youtu.be/7FjCK6o3laU
• Speed Logic offers professional installation; contact us for a quote.

Notes

• The AFS is designed only for port injection setups with the fuel rail mounted above the intake manifold. Plate-style spacer port injection is not supported by the standard kits; contact us first.
• The AFS is plug and play; no factory wiring needs to be cut.
• AFS.460 (601-0282), AFS.640 (601-0283) and AFS.745 (601-0284) are available to order; contact us for pricing.
• Price is for the item selected only; labor is not included.
• Confirm your engine code and chassis before ordering.

PART NUMBER

• 601-0281 — AFS.425, single Walbro 450
• 601-0285 — AFS.800, dual Walbro 535

VEHICLE APPLICATIONS