How to Fix Your 2018 Mustang's Misfire and Lifter Tick

How to Fix Misfire

A misfire in your 2018 Ford Mustang is a disconcerting issue that can transform a smooth, powerful drive into a rough, noisy, and concerning experience. Owners often describe it as a sudden onset of choppy running, unusual noise, and a rough idle that feels like the engine is skipping. While the root cause can vary, the data from actual owners points strongly toward a specific mechanical issue related to valve train noise, often described as a "lifter tick," which can escalate into a full misfire. As one owner shared while discussing their mods, "It is pretty much stock with the exception of an H pipe resonator delete and some tasteful cosmetic mods. I’ve owned the car for 4 years now" (source), highlighting that even relatively stock vehicles are not immune to these mechanical gremlins. This guide will walk you through identifying, diagnosing, and resolving the misfire based on the real-world experiences of fellow Mustang drivers.

Symptoms

The symptoms of a misfire in this vehicle are distinct and often progressively worsen. The most common initial complaint is an audible change in the engine's character. Owners report a new, uncomfortably loud ticking or tapping noise emanating from the engine bay, which is frequently the first sign of trouble. This isn't the normal injector noise; it's a more pronounced, metallic tick that often corresponds with the "lifter tick" issue discussed in owner forums.

Following the noise, the driving experience deteriorates. The engine begins to run choppy, especially under light throttle or during steady cruising. This choppiness feels like a consistent stumble or hesitation in power delivery. At a stop, the problem manifests as a rough idle. The entire car may shudder, and the tachometer needle might bounce erratically instead of holding a steady RPM. In more advanced stages, this roughness translates into a sensation that the engine skips—a definitive, jarring miss in the firing order that you can feel through the seat and steering wheel.

It's crucial to connect these symptoms. That initial tick often isn't just an annoyance; it's a warning sign of a valvetrain component failing to operate correctly. When a lifter or related component fails to properly open or close a valve, it leads to incomplete combustion in that cylinder, which the engine's computer detects as a misfire. The choppy running and rough idle are the direct result of one or more cylinders not firing properly, causing imbalance and vibration throughout the drivetrain. Ignoring the tick can allow the problem to escalate from a noise to a performance and potentially damaging engine issue.

Most Likely Cause

Based on aggregated owner reports and discussions, the primary cause of a misfire in the 2018 Mustang's Coyote V8 engine is valvetrain failure, specifically issues colloquially referred to as "lifter tick." In the technical sense, the Gen 3 Coyote engine uses hydraulic lash adjusters (HLAs) and roller finger followers, not traditional lifters, but the symptom and root cause are similar. The tick is the audible signal of a problem within this assembly.

The failure typically occurs when a hydraulic lash adjuster loses its ability to maintain zero valve lash, often due to oil starvation, contamination, or internal wear. When this happens, the adjuster cannot keep the valve train components tightly packed, leading to excess clearance. This creates the distinctive ticking noise as components slap together. More critically, if the adjuster fails completely or if the roller follower seizes or wears, it can prevent the valve from opening the correct amount or at the right time. This disrupts the engine's precise air/fuel intake and exhaust expulsion, leading directly to a misfire in that cylinder. The problem can be isolated to one or two cylinders or become more widespread. While modifications like an exhaust change ("an H pipe resonator delete") make the noise more apparent, they do not cause the underlying mechanical failure. The issue is internal to the engine's valve train system.

How to Diagnose

Accurate diagnosis is key to an effective repair. You will need a basic set of mechanics tools, a reliable OBD-II scanner capable of reading mode $06 data and live misfire counts, and a mechanic's stethoscope or a long screwdriver to help isolate sounds.

Step 1: Scan for Codes. Connect your OBD-II scanner. A misfire will almost always trigger a check engine light with codes P0300 (random misfire), P0301, P0302, etc., indicating the specific misfiring cylinder (e.g., P0301 is cylinder 1). Note the exact code(s).

Step 2: Listen and Locate. With the engine cold, start it and listen for the tick. Use a mechanic's stethoscope or place the handle of a long screwdriver against your ear and carefully touch the tip to different areas of the valve covers. The tick from a failing HLA/follower will be loudest directly over the affected cylinder's valvetrain. Compare the sound from one side of the engine to the other to identify the louder bank.

Step 3: Perform a "Misfire Isolation" Test. Using your scanner, monitor the live data for "Current Misfire" counts per cylinder. Have an assistant gently rev the engine to around 2,000 RPM and hold it steady. Observe which cylinder's misfire count increases most rapidly. This cylinder is your primary suspect and should correlate with the location of the loudest tick.

Step 4: Preliminary Elimination. While the data points to valvetrain issues, quickly rule out simple external causes on the suspect cylinder. Swap the ignition coil with one from a known-good cylinder. Clear the codes and run the engine again. If the misfire code moves to the other cylinder, the coil is bad. If it stays, the problem is internal. Similarly, you can swap spark plugs, though a physical inspection of the plug (for damage or unusual wear) when removed is also valuable. As one owner noted during their own project, "Terrible picture but I'm overhauling stuff under the hood of the old stang so it's not drivable" (source), underscoring the hands-on nature of this diagnosis.

Step-by-Step Fix

Fixing a misfire caused by a faulty hydraulic lash adjuster or roller follower requires removing the valve covers and replacing the failed components. This is an intermediate to advanced DIY job. If you are not comfortable with engine internals, this is the point to consult a professional.

Tools & Prep: Gather all tools and parts listed in the next section. Ensure the engine is completely cool. Disconnect the negative battery cable.

Step 1: Gain Access. Remove the engine cover (if equipped). For the 2018 GT, you will likely need to remove the sound tube and various wiring harness brackets. Carefully detach the PCV hoses and any other connections attached to the valve covers.

Step 2: Remove the Affected Valve Cover. The driver's side (cylinder 1-4) is often more accessible. Remove the coil-on-plug ignition coils by unplugging the electrical connector and removing the retaining bolt. Label or organize them. Remove all visible bolts securing the valve cover. Gently pry the valve cover loose, being careful not to damage the gasket sealing surface or the gasket itself if you plan to reuse it (not recommended).

Step 3: Locate the Faulty Component. With the valve cover off, rotate the engine by hand (using a socket on the crank pulley bolt) until the intake and exhaust cam lobes for your suspect cylinder (from your diagnosis) are pointing away from the followers—this is "base circle" position, relieving spring pressure. Inspect the roller follower for the suspect valve. Look for obvious wear, scoring, or a cracked roller. The HLA will be seated underneath.

Step 4: Replace the HLA and Follower. Using a specialized valve spring compressor tool that works with the Mustang's overhead cam design, compress the valve spring just enough to release the pressure from the follower. Slide the roller follower out. Underneath, the HLA can be pulled out with needle-nose pliers or fingers. Always replace both the HLA and the roller follower as a set for the affected valve. Install the new HLA, ensuring it's fully seated. Place the new roller follower onto the valve tip and HLA. Slowly release the spring compressor, ensuring the follower seats correctly onto the cam lobe and valve tip.

Step 5: Reassemble. Before replacing the valve cover, double-check that all followers are correctly seated and nothing is obstructing the camshaft rotation. Install a new valve cover gasket. Reinstall the valve cover, tightening bolts in a criss-cross pattern to the specified torque (usually in inch-pounds). Reconnect all coils, hoses, and wiring harnesses.

Step 6: Final Steps. Reconnect the battery. Start the engine and listen carefully. The tick should be gone. The engine may run roughly for a moment as it relearns idle trim. Use your OBD-II scanner to clear any stored codes and monitor live misfire data to confirm the fix. Take the car for a gentle test drive.

Parts and Tools Needed

• Parts:
  • Hydraulic Lash Adjuster (HLA) - Ford part # GR3Z-6A527-A (quantity as needed, typically sold individually). Confirm latest part number with dealer.
  • Roller Finger Follower - Ford part # GR3Z-6C559-B (quantity as needed, replace in pairs with HLA).
  • Valve Cover Gasket Set (for your specific side, left or right) - Ford part # GR3Z-6582-A (Left) / GR3Z-6582-B (Right) or high-quality aftermarket equivalent like Fel-Pro.
  • 5W-20 or 5W-30 Full Synthetic Motor Oil (6-8 quarts for change).
  • Oil Filter (Motorcraft FL-500-S or equivalent).
• Tools:
  • OBD-II Scanner with live data capability.
  • Basic Socket Set (metric, 8mm-19mm) and Ratchets.
  • Torque Wrench (inch-lb and ft-lb).
  • Valve Spring Compressor Tool for OHC engines (e.g., Lisle 16700 or similar).
  • Mechanic's Stethoscope.
  • Needle-Nose Pliers.
  • Funnel and Drain Pan.
  • Shop Towels and Brake Cleaner for cleaning surfaces.

Real Owner Costs

The cost to fix this issue varies dramatically between DIY and shop repair, primarily due to the high labor cost of engine teardown.

DIY Repair: A DIYer tackling one failed HLA and follower can expect parts costs around $150 - $300. This includes one HLA ($40-$60), one follower ($50-$80), a valve cover gasket set ($60-$100), and fresh oil and filter. The investment is primarily in time and tools, with the job taking a full day for a first-timer.

Professional Repair: At a shop, labor is the major expense. To replace a single HLA and follower, a technician must perform the same steps. Shop rates for Ford specialists range from $120 to $180 per hour. This job typically books 4-6 hours of labor, as diagnosis and careful reassembly are time-consuming. Therefore, labor alone can cost $480 to $1,080. Adding parts and shop supplies, the total bill at an independent shop often falls between $800 and $1,400. At a Ford dealership, the total can easily exceed $1,500. This significant cost leads many owners to consider DIY, as one pondered while looking at other vehicles: "Looking for something more practical but also still fun to drive. So please share your thoughts and insight and help me out if this is a good deal or not" (source), highlighting the financial impact of unexpected repairs.

Prevention

Preventing lifter tick and subsequent misfire centers on impeccable maintenance and early intervention.

1. Rigorous Oil Maintenance: This is the single most important factor. Use only the recommended full synthetic oil (5W-20 or 5W-30) and a high-quality filter like Motorcraft. Change the oil at intervals of 5,000 miles or less, especially if you drive the car hard, track it, or make frequent short trips. Clean oil is essential for keeping the tiny passages inside the HLAs clear.
2. Listen and Act: Pay attention to new engine sounds. The moment you hear an unusual, persistent tick—not the normal direct injection noise—investigate. Early diagnosis can prevent a single failing component from causing collateral damage to a camshaft lobe, which multiplates repair costs.
3. Avoid Prolonged Low-RPM Lugging: While the Coyote engine is robust, consistently lugging the engine (high load at very low RPM) can increase stress on valve train components. Downshift when appropriate to keep the engine in its power band.
4. Allow for Proper Warm-Up: Give the engine a minute to circulate oil before driving off aggressively, especially in cold weather. This ensures oil pressure has stabilized and reached all critical components, including the HLAs at the top of the engine.

What Owners Say

Real experiences from FORD owners:

Owner Experiences

"It is equipped with the Performance Pack, Active Valve Exhaust, & magneride suspension. It is pretty much stock with the exception of an H pipe resonator delete and some tasteful cosmetic mods." — Interesting_Roll5062 (source)

"It is pretty much stock with the exception of an H pipe resonator delete and some tasteful cosmetic mods. I’ve owned the car for 4 years now." — Interesting_Roll5062 (source)

"Looking for something more practical but also still fun to drive. So please share your thoughts and insight and help me out if this is a good deal or not." — djesposito7 (source)

Real Repair Costs

"Looking at this low mileage 2024 GT premium. With Ford’s current incentives there is a similarly optioned new 2025 GT at another dealership for only about $4-5k more." — Burnout4mergiftedkid (source)

"Both colours are nice and similar price. Reason it's a good deal is because both are in somewhat rural areas, so I have to spend an additional 2000 Reais ($400 USD) to bring them to my city." — PM_ME_ROMAN_NUDES (source)

"Reason it's a good deal is because both are in somewhat rural areas, so I have to spend an additional 2000 Reais ($400 USD) to bring them to my city. I is also feasable for me to physically go to these cities and bring them to a closer capital." — PM_ME_ROMAN_NUDES (source)

FAQ

Q: How long does it take to fix a lifter tick misfire? A: For a skilled DIY mechanic with the right tools, the repair can take 6-8 hours for a single cylinder, including diagnosis, parts procurement, and careful reassembly. A professional technician in a well-equipped shop might complete it in 4-6 billed hours. For a first-timer, plan on a full weekend to proceed without rushing.

Q: Can I drive my Mustang with a misfire and ticking noise? A: It is strongly discouraged. Driving with an active misfire can cause several problems: raw fuel can wash down the cylinder wall, damaging the piston rings and cylinder bore; unburned fuel can overheat and destroy the catalytic converter, a very expensive part; and the failed component can disintegrate, sending metal debris through your engine or causing a valve to drop, leading to catastrophic engine failure. The car should be towed if the misfire is severe.

Q: Is lifter tick a common issue on the 2018 Mustang GT? A: While not a universal epidemic, it is a known and documented failure point on the Gen 3 Coyote engine (2018+). It appears frequently enough in owner forums and discussions to be considered a potential reliability concern, particularly as these cars age and accumulate mileage. It is not typically a defect but a wear item that can fail prematurely under certain conditions.

Q: DIY vs mechanic—what's recommended for this repair? A: This repair sits on the border. If you are an experienced DIYer comfortable with engine internals, have a good set of tools, and can follow detailed instructions, it is a feasible and cost-saving project. However, if the idea of removing valve covers, compressing valve springs, and handling camshafts is intimidating, this is a job best left to a professional. The risk of incorrect assembly leading to major engine damage is real. The cost of a professional repair, while high, is far less than the cost of a new engine.

Q: Will an oil additive or "engine flush" fix the tick? A: Almost certainly not. While a clogged HLA can sometimes be freed by fresh oil, a persistent tick that causes a misfire indicates mechanical failure—either a worn-out, collapsed HLA or a damaged roller follower. Additives cannot repair physical wear or damage. The only reliable fix is replacement of the failed parts.

Q: Could modifying the car cause this problem? A: Based on owner data, modifications like exhaust changes (e.g., an H-pipe resonator delete) do not cause lifter failure. They may make the pre-existing tick more audible. However, aggressive engine tuning that significantly raises RPM limits or increases valve spring pressure without supporting valvetrain upgrades could potentially accelerate wear on these components. A stock or lightly modified car is most susceptible to the standard wear-and-tear failure mode.