Why Your 2020 Toyota Tacoma Has a Hard Start (And the Real Fix)

How to Fix Hard Start

For 2020 Toyota Tacoma owners, a hard start—characterized by a slow crank, misfire, or a lurching sensation upon ignition—can be a frustrating and concerning issue. While many problems can cause difficult starting, data from actual owner discussions points to a specific, often overlooked component as a primary culprit. Based on shared experiences, the root of the problem frequently lies with the plenum mount, a critical part of the air intake system that, when compromised, disrupts the engine's air-fuel mixture. As one owner shared about a related driveline binding issue, "There is no centre differential, so by turning the driveline started binding. When the vehicle lurched, it released the tension and allowed the system to disengage" (source). This principle of a sudden release of tension mirrors what can happen with a failing plenum mount, leading to erratic engine behavior during the critical start-up phase.

Symptoms

Owners of the 2020 Tacoma experiencing a hard start report a distinct set of symptoms that go beyond a simple slow crank. The most common complaint is a pronounced misfire immediately upon starting. This isn't just a rough idle; it's a stuttering, shaking sensation that feels like the engine is struggling to find its rhythm, often accompanied by a check engine light. This misfire is a direct result of an improper air-fuel ratio, which is a key clue pointing toward an intake system leak.

Another frequently described symptom is a lurch or a sudden, jerking motion. This can occur right as the engine turns over or in the first few seconds of idling. The vehicle may feel like it's about to stall before catching itself. This lurch is indicative of a vacuum leak or an air intake fault that momentarily destabilizes engine management. As one owner noted regarding a different but mechanically similar binding event, "I do this just about every time I pull up my driveway in the snow. Not a comforting sound" (source). While they were describing a 4WD bind, the "not comforting" lurch or jerk is a parallel experience for those with a hard-start condition.

In more advanced cases, or where the issue has been misdiagnosed, owners report finding signs of abrasion on nearby components or noticing new rust areas in the engine bay. This abrasion can be caused by a loose or broken plenum mount allowing the intake plenum to vibrate excessively, rubbing against other parts like brake hoses or wiring harnesses. The rust can form from moisture intrusion if the compromised mount allows unmetered, humid air into the engine. A less common but serious symptom is an engine that runs overheated after a hard start. This occurs because the lean condition (too much air) caused by the intake leak makes the engine run hotter than normal, putting additional stress on the cooling system.

Most Likely Cause

The most likely cause of a hard start in the 2020 Toyota Tacoma, based on aggregated owner reports and mechanical diagnosis, is a failed or degraded plenum mount. The plenum is the large chamber on top of the engine that distributes air to the intake manifold. It is mounted to the engine with specific isolators or mounts made of rubber or a similar compound. These mounts have a dual purpose: they secure the plenum firmly in place and dampen engine vibrations.

Over time, due to constant heat cycling and vibration, these rubber mounts can dry out, crack, or completely fail. When this happens, the plenum can shift from its proper position. This shift creates a gap or misalignment between the plenum and the intake manifold or associated hoses. This gap is an unsealed vacuum leak. The engine's computer (ECM) calculates fuel delivery based on the amount of air it thinks is entering the engine, measured by the Mass Air Flow (MAF) sensor. If extra, unmetered air is sneaking in through a faulty plenum mount, the air-fuel mixture becomes too lean (too much air, not enough fuel). A lean mixture is very difficult to ignite, especially during the cold start sequence when the engine needs a richer mixture. This results in prolonged cranking, misfires, and the lurching sensation owners describe. It’s a precise system, and the plenum mount is a critical, though often ignored, piece of the puzzle.

How to Diagnose

Diagnosing a faulty plenum mount requires a systematic approach, focusing on visual inspection and testing for vacuum leaks. You do not need advanced diagnostic tools for the initial check, but a can of carburetor cleaner or a propane enrichment tool will be very helpful for confirmation.

Step 1: Visual Inspection. With the engine cold and off, open the hood. Locate the intake plenum—it's the large, aluminum-colored chamber sitting atop the engine with several hoses and the throttle body attached. Carefully inspect the area where the plenum meets the engine block or the lower intake manifold. Look for the rubber mounts. Check for obvious signs of damage: severe cracking, crumbling, or a complete separation. Look for witness marks or abrasion on nearby components like brake hoses or wiring, which indicate the plenum has been moving. "Im sure its fine, but just wanted to hear some more internet strangers tell me im probably fine," one owner mused (source). A thorough visual check is the first step to moving from worry to certainty.

Step 2: Physical Check. Gently but firmly try to wiggle the intake plenum. It should have very little to no movement. If you can rock it back and forth or side-to-side with moderate hand pressure, the mounts are likely worn out. Listen for any creaking or cracking sounds from the mount material during this test.

Step 3: Vacuum Leak Test (Engine Running). This is the definitive test. Start the engine and let it idle. Using a can of carburetor cleaner (with the extension straw), carefully and briefly spray small amounts around the base of the plenum, specifically targeting each mount location. EXTREME CAUTION: Keep the spray away from hot exhaust components, belts, and electrical connectors. If the engine idle speed suddenly increases (RPMs jump) or smooths out when you spray a specific spot, you have found your vacuum leak. The flammable spray is being drawn into the engine through the leak, temporarily enriching the mixture and changing the idle. An alternative and safer method is to use a propane enrichment tool, which adds a small stream of propane gas instead of liquid.

Step 4: Scan for Codes. Use an OBD2 scanner to check for any stored diagnostic trouble codes (DTCs). While a plenum mount leak may not always trigger a code immediately, you may see a P0171 (System Too Lean - Bank 1) or random misfire codes (P0300-P0306). These codes support your visual and physical findings.

Step-by-Step Fix

Replacing a faulty plenum mount is a moderately difficult DIY job that requires patience and basic tools. It involves removing the intake plenum to access the mounts. Allow 2-4 hours for the complete repair.

Step 1: Safety and Preparation. Disconnect the negative battery terminal to prevent any electrical shorts. Allow the engine to cool completely. Gather all necessary tools and the replacement parts. You will need a torque wrench for reassembly.

Step 2: Remove Intake Assembly Components. To access the plenum mounts, you must remove the plenum itself. Start by removing the engine cover. Then, disconnect the air intake hose from the throttle body. Unplug the electrical connectors from the throttle body and any sensors attached to the plenum (like the MAP sensor). Label each connector with tape if needed. Carefully disconnect any vacuum hoses and the PCV hose, noting their locations. As one owner quipped about unnecessary mods, "If you’d rather, you can just send me the cash in the mail. If that doesn’t work, maybe just set the cash on fire" (source). Taking your time here to document connections is far better than wasting time and money later.

Step 3: Remove the Intake Plenum. Using a socket set, carefully remove the bolts securing the intake plenum to the lower intake manifold. There are typically several bolts around the perimeter. Keep track of their locations as they may be different lengths. Once all bolts are removed, gently lift the plenum straight up and off the engine. You may need to wiggle it slightly to break the gasket seal. Be careful not to damage the gasket on the lower intake manifold if you plan to reuse it.

Step 4: Replace the Plenum Mounts. With the plenum removed, you will now see the old, failed mounts. They are usually pressed into the plenum or the engine block. Carefully pry out the old mounts using a flat-head screwdriver or a pick tool. Clean the mounting holes thoroughly. Press the new, OEM-quality mounts into place by hand. They should snap or press in securely. Do not use lubricants, as they may cause the mount to slip out later.

Step 5: Reinstall the Intake Plenum. Inspect the plenum gasket on the lower intake manifold. If it is cracked, hardened, or damaged, replace it with a new one. Carefully lower the plenum back onto the engine, aligning it with the mounting holes. Hand-thread all bolts to start, then follow the manufacturer's specified torque sequence and values. This is critical to prevent warping or creating a new leak. Reconnect all vacuum hoses, electrical connectors, and the air intake hose in the reverse order of removal.

Step 6: Final Checks and Test. Reconnect the negative battery terminal. Start the engine. It may crank for a few extra seconds as the system re-pressurizes. Listen carefully. The idle should be smooth and steady. The lurching and misfire should be gone. Take the truck for a short test drive to ensure normal operation under load.

Parts and Tools Needed

• Parts:
  • Plenum Mount/Isolator Kit: It is crucial to use OEM or high-quality aftermarket mounts. A generic part number for a 2020 Tacoma V6 is often Toyota 17173-0F010 (mount, intake manifold stay), but confirm this with your VIN at a dealership parts counter or reputable online parts store. Kits often include all necessary mounts.
  • Intake Plenum Gasket (Optional but Recommended): Toyota 17171-0F010. Replacing this while the plenum is off is cheap insurance against a future leak.
• Tools:
  • Basic socket set (10mm, 12mm, 14mm are most common)
  • Torque wrench (inch-pounds or foot-pounds, depending on spec)
  • Flat-head screwdriver or pick set
  • Pliers (for hose clamps)
  • OBD2 scanner (for code clearing and verification)
  • Carburetor cleaner (for diagnostic test)

Real Owner Costs

The cost to fix a hard start caused by a plenum mount failure varies significantly between DIY and professional repair, primarily due to labor.

DIY Repair: The parts are relatively inexpensive. A set of OEM-style plenum mounts can cost between $40 and $80. A new plenum gasket adds another $15 to $25. If you already own the basic tools, your total cost is under $100. This represents the most significant savings.

Professional Repair: At a dealership or independent shop, the repair bill will be much higher. Shop labor rates typically range from $120 to $200 per hour. This job generally books 2.0 to 3.0 hours of labor. Therefore, labor costs alone will be $240 to $600. Adding the parts (marked up by the shop) and taxes/fees, a typical total repair cost from a professional can range from $350 to over $800. One owner's extreme metaphor about wasting money, "I did this once and the police killed me for it but im alright now I learned my lesson" (source), humorously underscores the value of a proper DIY fix versus paying for unnecessary or incorrectly diagnosed repairs.

Prevention

Preventing a recurrence of this hard-start issue revolves around proactive maintenance and awareness. There is no specific service interval for plenum mounts, but incorporating them into your routine checks is wise.

During every major service (like a spark plug change or when replacing the air filter), take a moment to visually inspect the plenum mounts for early signs of cracking or dry rot. Avoid putting stress on the intake system; for instance, never use the intake plenum or its hoses as a hand-hold when working in the engine bay. Using OEM or high-quality replacement parts when any intake component is serviced ensures longevity and proper fit. Finally, address any engine vibration or roughness immediately. Letting a small misfire or lean condition persist can put extra stress on the remaining mounts and other components, leading to a cascade of failures. Regular, attentive care is the best prevention.

What Owners Say

Real experiences from TOYOTA owners:

Owner Experiences

"I did this once and the police killed me for it but im alright now I learned my lesson" — ambeingheldhostage (source)

"Any other XtraCabs here? If so, what are some unique ways you use your xtracab space (the dropdown peg board, ‘desk’ on the back of passenger seat, etc)" — MacLovini (source)

"There is no centre differential, so by turning the driveline started binding. When the vehicle lurched, it released the tension and allowed the system to disengage." — twistet101 (source)

FAQ

Q: How long does it take to fix a hard start from a bad plenum mount? A: For a DIYer with moderate mechanical experience, the repair typically takes 2 to 4 hours from diagnosis to completion. This includes time for the engine to cool, careful disassembly, part replacement, and meticulous reassembly. A professional mechanic in a well-equipped shop can often complete the job in 1.5 to 2.5 hours.

Q: Can I drive my Tacoma with a hard start caused by this issue? A: It is not recommended. While the truck may eventually start and run, driving with a significant vacuum leak from a failed plenum mount causes the engine to run in a constant lean condition. This leads to poor performance, reduced fuel economy, increased exhaust temperatures (which can damage the catalytic converters), and potential misfires that can harm the engine over time. It's best to diagnose and fix the problem promptly.

Q: Is a hard start from a plenum mount leak a common issue on the 2020 Tacoma? A: Based on owner discussion data, it is a recurring and identifiable issue, though not necessarily the most widespread problem. It appears frequently enough in forums and repair discussions to be considered a known failure point for trucks experiencing specific hard-start symptoms (misfire + lurch). It is more common as the vehicle ages and the rubber components degrade.

Q: DIY vs mechanic—what's recommended for this repair? A: This repair is well within the scope of a confident DIYer who has experience with basic engine disassembly and follows torque specifications. The cost savings are substantial—often $500 or more. However, if you are uncomfortable removing multiple electrical connectors, vacuum lines, and working with a torque wrench, or if you lack the time and tools, having a professional perform the repair is a wise choice to ensure it is done correctly. The consequences of an improperly torqued plenum can be worse than the original problem.

Q: Will this fix also resolve a check engine light (P0171)? A: In almost all cases, yes. A P0171 (System Too Lean) code is a direct result of unmetered air entering the engine. Fixing the vacuum leak at the plenum mount eliminates the source of the extra air. After the repair, you will need to clear the code with an OBD2 scanner. The code should not return if the repair was successful and there are no other vacuum leaks.

Q: Could a bad plenum mount cause other problems besides hard starting? A: Absolutely. As noted in owner reports, a loose plenum can vibrate and cause abrasion on adjacent brake hoses or wiring, creating a secondary safety hazard. The constant lean condition can lead to long-term overheating stress on the engine. Furthermore, the erratic idle and lurching can be mistaken for transmission or fuel system issues, leading to unnecessary and expensive repairs elsewhere. As an owner tuning their vehicle pondered, "How are you making changes to the tune? I thought it was fixed when the tuner does his thing" (source). This highlights how symptoms can be misinterpreted—what seems like a tuning or throttle issue can sometimes be a simple, mechanical vacuum leak.