Deleting AFM (Active Fuel Management) from your 5.3L or 6.0L GM truck is the single most effective long-term reliability upgrade you can do. This guide covers the full process: what parts you need, what you can reuse, how to do the cam swap correctly, and what tune you absolutely cannot skip. This is not a diagnostic guide — for diagnosing AFM lifter failure first, see our AFM/DOD Lifter Failure Guide. This is the fix-it-for-good guide.

Why Delete AFM?

AFM (also called DOD — Displacement on Demand) deactivates cylinders 1, 4, 6, and 7 during light-load cruise to improve fuel economy. In practice, the fuel savings are marginal (1–2 MPG at best), and the system introduces four failure points that don’t exist in a non-AFM engine: collapsing AFM lifters. When an AFM lifter fails, the lobe drops contact with the cam, the cylinder loses compression, and you get a misfire, a tick, and eventually metal debris circulating through your oil system. The AFM delete eliminates all four of those failure points permanently.

AFM delete is appropriate for: any truck that has already had an AFM lifter failure, any high-mileage 5.3 or 6.0 truck as preventive maintenance, and any build where the engine will be tuned or modified beyond stock.

Affected Engines

• LC9 / LY5 / LMG 5.3L (GMT900, 2007–2013): Most common AFM delete candidates. OHV pushrod V8 with 4 AFM cylinders.
• L83 / L82 5.3L EcoTec3 (K2XX, 2014–2018): Same AFM architecture, different cam spec. Parts are NOT interchangeable with Gen IV — confirm application before ordering.
• LY6 / L96 6.0L (GMT900, HD trucks): AFM-equipped in many trim levels. Same delete process, different cam part number.
• LQ4 / LQ9 6.0L (GMT800 pre-AFM): Do NOT have AFM. No delete needed.

Parts List — What You Need

Required Parts

• Non-AFM camshaft: This is the core of the delete. You need a cam without the AFM lobe profiles. For a stock-power delete (no performance increase, just reliability): use a GM Performance Parts cam (p/n 12586481 for most 5.3 Gen IV) or a matched aftermarket non-AFM cam (COMP Cams, Lunati). For a mild performance upgrade: COMP Cams 54-422-11 or similar — adds 20–30 hp while eliminating AFM.
• 16 new lifters (non-AFM): Replace ALL 16 lifters — not just the 4 AFM ones. If you’re already in there with the cam out, replacing only the failed lifters is a mistake. Non-AFM lifters: Delphi HL124 (set of 16) or equivalent. Do not reuse any existing lifters regardless of apparent condition.
• Valley cover / AFM delete plate: The stock valley cover has oil passages specifically for AFM solenoids. You must replace it with an AFM delete valley cover (also called a DOD delete plate) that blocks those passages. Dorman 615-906 or equivalent. This is non-negotiable — without it, the AFM solenoid passages will bleed oil pressure.
• Timing chain kit: Since you’re already at the front of the engine with the timing cover off, replace the timing chain, tensioners, and guides. GM trucks with 80K+ miles frequently have stretched chains. Replacing now costs ~$80 in parts and zero additional labor. Skipping it and having the chain fail later means doing the entire job again. Recommended: Melling or COMP Cams timing set for your application.
• Camshaft thrust plate: Replace with a new one — they wear and are cheap insurance.
• Valley gasket set: For the new valley cover and intake manifold reseating.
• Intake manifold gaskets: Must come off to access the valley. Replace the gaskets — reusing them risks intake leaks.
• Fresh engine oil + filter: Full oil change after reassembly is mandatory. Use a quality 5W-30 (Mobil 1 or Dexos-approved full synthetic) and a new AC Delco filter.

Optional but Recommended

• New pushrods: If you’re changing cam lift significantly (more than ~0.050″ difference), you may need longer pushrods. Measure with a pushrod length checker or use a Smith Bros. custom-length set if doing a performance cam.
• Cylinder head gaskets: If the truck has over 150K miles or any history of overheating, resurface and re-gasket the heads while they’re accessible. Marginal cost in labor at this stage vs. a standalone head gasket job later.
• Oil pump and pickup tube: A worn oil pump is one of the contributing factors to AFM lifter failure. Melling M295 is a direct replacement. Add $60 in parts while the pan is accessible.

Tools Required

• Engine hoist or support (to drop the front crossmember or support the engine for timing cover removal — depends on your workspace)
• Cam bearing installation tool (for reinstalling the new cam bearing if you’re replacing it — most deletes reuse the existing cam bearings unless damaged)
• Cam phaser holding tool (GMT900/K2XX only — required to hold the cam phasers in position while torquing the phaser bolts)
• Torque wrench (cam phaser bolt: 18 lb-ft + 135° on Gen IV/EcoTec3)
• Lifter removal tool or small magnetic pickup — lifters can stick in their bores
• Assembly lube (mandatory for cam lobes and lifter faces — COMP Cams Ultra-Lube or similar zinc-based assembly lube)
• Degree wheel (if degreeing the cam for a performance grind)

Step-by-Step AFM Delete Process

Step 1: Drain Oil, Disconnect Battery

Drain the engine oil completely. Disconnect the negative battery terminal. Remove the air intake assembly for access.

Step 2: Remove Intake Manifold

Disconnect all vacuum lines, fuel injector harnesses, throttle body wiring, and coolant lines at the throttle body. Remove the 10 intake manifold bolts (8mm) in reverse of torque sequence. Lift the intake off. Plug all open ports immediately with clean shop rags — debris in the intake ports is a major risk here.

Step 3: Remove Valley Cover

Remove the AFM solenoid connectors and the AFM solenoids (4 total). Remove the valley cover bolts. Lift off the valley cover. Discard — it will be replaced with the delete plate.

Step 4: Remove Pushrods and Lifters

Remove all 16 rocker arms (10mm bolt each). Remove all 16 pushrods — keep them in order in a cardboard rack if you intend to reuse them. Remove all 16 lifters using a lifter removal tool. If lifters are stuck (common with collapsed AFM lifters), use a slide hammer or pick. Discard all 16 lifters — do not reuse any.

Step 5: Remove Timing Cover and Timing Components

Remove the serpentine belt, harmonic balancer (harmonic balancer puller required), and the timing cover (multiple bolts of varying lengths — document which length goes where). Remove the timing chain, tensioner, and guides. Discard and replace with new kit.

Step 6: Remove and Replace the Camshaft

Remove the camshaft thrust plate bolt (one center bolt on Gen IV). Carefully pull the camshaft straight out — rotate slightly if it hangs on a lobe but do not force. Inspect cam bearings in the block for wear or scoring. If bearings are good, leave them. If scored, press them out and install new ones before the new cam goes in.

Coat every lobe of the new camshaft with assembly lube before installation. Slide the new cam in carefully — same procedure as removal. Install new thrust plate and torque the bolt to spec (18 lb-ft on Gen IV).

Step 7: Install New Timing Chain

Install new timing chain, tensioner, and guides per the timing set instructions. Verify correct cam-to-crank timing marks alignment. If doing a performance cam, degree the cam per the cam card specifications before final assembly.

Step 8: Install New Lifters

Coat each new lifter face with assembly lube. Install all 16 non-AFM lifters in their original bores (if reusing pushrods, reinstall in their original positions). Install pushrods — verify they’re seated in the lifter cup and rocker arm seat before torquing rockers. Torque rocker arms to spec (22 lb-ft on most Gen IV applications).

Step 9: Install AFM Delete Valley Cover

Install the new AFM delete valley cover (Dorman 615-906 or equivalent) with new gasket. Torque bolts to spec in sequence. Do not install the AFM solenoids — the delete plate has no ports for them.

Step 10: Reinstall Intake Manifold and Timing Cover

Reinstall timing cover with new gasket and RTV where specified. Reinstall harmonic balancer (installation tool required — do not hammer it on). Reinstall intake manifold with new gaskets — torque bolts in sequence to 89 in-lb (7.4 lb-ft). Reconnect all vacuum lines, injector harnesses, and throttle body connections.

Step 11: Fill Oil, Pre-lube, Start

Fill with fresh 5W-30 full synthetic (5 quarts minimum — confirm capacity for your application). Before starting, cycle the ignition to “on” (no crank) for 5 seconds, then off, then on again — do this 5–6 times to pre-pressurize the oil system and get oil to the new lifters before the first fire. This step is critical for new lifter break-in. Then crank and start. Idle at 2,000 RPM for 20 minutes on initial break-in of a new cam. Do not let it drop to idle — the cam break-in requires RPM above idle for proper lobe surface hardening.

The Tune — Non-Negotiable

You cannot do an AFM delete without a tune. The ECM still has AFM logic programmed — it will attempt to activate AFM solenoids that no longer exist, throw codes (P3401, P3425, etc.), and run the engine on incorrect fuel tables. A tune must: disable AFM in the ECM, update VVT parameters if the cam profile changed, and adjust fuel/ignition tables for the new cam if applicable.

Tune options:

• Diablosport inTune i3 / Trinity T2: Handheld tuner with preloaded AFM disable tune for most GMT900/K2XX 5.3s. Easiest DIY option — plug in, load tune, done. Typically $150–$300 for the device. Not as precise as a custom tune but eliminates AFM codes and enables a no-AFM drive experience.
• HP Tuners with custom tuner: Best result. A custom tune from a known GM tuner (many on the FullSizeChevy forum) dials in fuel trims, VVT, and transmission shift points alongside the AFM delete. Cost: $200–$400 for the tune file. Requires HP Tuners MPVI2 interface (~$300) or the tuner can flash it remotely if you have a compatible interface.
• EFILive: Same tier as HP Tuners — preferred by some tuners. Same cost range.

What to Expect After the Delete

• Fuel economy: Unchanged to marginally worse — AFM was only saving 1–2 MPG at best, and a properly tuned AFM delete often matches or beats the AFM fuel economy because the ECM isn’t switching in and out of deactivation mode.
• Engine sound: The V8 sounds like a V8 all the time now. No more 4-cylinder drone at cruise.
• Reliability: The four highest-risk failure points in the engine are gone. This is the most impactful reliability mod you can do on a Gen IV 5.3.
• Idle quality: With a stock-power cam, idle is unchanged. With a performance cam, expect a rougher, lumpier idle depending on cam specs.

Worth measuring instead of arguing about: log a few tanks before the job and a few after in the Fuel Mileage Calculator so you have your own before-and-after numbers rather than somebody else’s.

Discuss Your AFM Delete on the FSC Forum

Done an AFM delete? Currently planning one? Hit a snag mid-job? Post your engine, mileage, parts choices, and what you found in the FSC GMT900 / K2XX community threads. Members share real-world lifter failure photos, tune file recommendations, and shop labor quotes from across North America.

👉 Join the AFM delete discussion on the FSC Forum

Related Guides

• AFM/DOD Lifter Failure — Diagnosis Guide (is it failed? start here first)
• 5.3 Ticking Noise Diagnosis
• GMT900 Complete Owner’s Guide
• K2XX Silverado Complete Guide
• LS Swap Guide (if the engine is too far gone to save)

Learn more about which Chevy truck years are most reliable overall: Most Reliable Chevy Truck — Year by Year Guide.

For the GMT900-specific failure guide: GMT900 AFM lifter failure — full guide.

See also

Diagnosing the tick first? Start with the complete guide: AFM / DoD in Chevy & GMC Trucks.