Why Your 2017 Chevy Spark is Shaking With a Misfire (And How to Stop It)

How to Fix Misfire

A persistent misfire in your 2017 Chevrolet Spark can be a frustrating and worrying experience, often marked by shaking, check engine lights, and a loss of confidence in the vehicle. However, based on real-world owner experiences, this problem is often solvable with a methodical approach, starting with the most common and affordable culprits. As one owner shared about their similar struggle: "For the past month and a half I’ve taken it in to get worked on for the engine feeling like it’s shaking and throwing codes for misfiring." Their journey to a fix, which we'll detail, highlights the importance of not giving up.

Symptoms

Owners experiencing a misfire report a very distinct and unsettling set of sensations and warnings. The most common symptom is a pronounced physical shaking or vibration felt throughout the vehicle, especially at idle or during acceleration. This isn't a minor buzz; it's a clear indication that one or more cylinders are not firing correctly, throwing the engine's balance off.

This shaking is almost always accompanied by the illumination of the check engine light. When scanned, this light will typically reveal diagnostic trouble codes (DTCs) specific to a misfire, such as P0300 (random misfire) or P0301-P0304 (misfire detected in a specific cylinder). You may also notice a lack of power, hesitation when you press the gas pedal, and rough idling that makes the whole car feel unstable.

In some cases, the misfire can be severe enough to cause stalling, particularly when coming to a stop. Other related symptoms mentioned by owners dealing with underlying causes include unusual smells and a high-pitched whine from the engine bay, which can point to a vacuum leak—a common companion to misfire issues. The combination of these symptoms creates a driving experience that feels broken and unreliable.

Most Likely Cause

Based on aggregated owner reports and repair experiences, the most likely primary cause of a recurring misfire, especially one that returns after basic tune-up parts are replaced, is a faulty Positive Crankcase Ventilation (PCV) valve. This small, inexpensive part plays a critical role in engine health. Its job is to regulate the flow of blow-by gases (unburned fuel, air, and combustion byproducts) from the crankcase back into the intake manifold to be burned off.

When the PCV valve fails—either by sticking open or closed—it disrupts this delicate balance. A stuck-open valve can create a significant vacuum leak, allowing unmetered air into the intake. This leans out the air/fuel mixture and can directly cause misfires, particularly at idle. A stuck-closed valve allows pressure to build in the crankcase, which can force oil past seals and into the combustion chamber via the piston rings or valve guides. This oil fouls spark plugs, leading to immediate misfires. As one owner succinctly diagnosed a related issue: "The cause of your oil consumption is stuck oil control rings. For about $125, you can solve this problem... including... a new PCV valve." This highlights how a failing PCV system can trigger a cascade of problems that manifest as a misfire.

How to Diagnose

Proper diagnosis saves time and money by preventing unnecessary parts replacement. Start by using an OBD2 scanner to read the check engine light codes. Note the specific misfire codes. A code for a random misfire (P0300) suggests a system-wide issue like a vacuum leak or bad fuel, while a code for a specific cylinder (e.g., P0301 for cylinder 1) points you to a more localized problem.

For a specific-cylinder misfire, begin with a visual inspection. Swap the ignition coil from the misfiring cylinder with one from a known good cylinder. Clear the codes, drive the vehicle, and re-scan. If the misfire code moves to the other cylinder, you've found a bad coil. If it stays on the original cylinder, the coil is likely fine. Repeat this process with the spark plug. Inspect the old plug for signs of oil fouling, excessive carbon, or damage.

If the misfire persists or is random, investigate the PCV system. With the engine running at idle, listen for a hissing sound around the intake manifold and PCV hoses, indicating a vacuum leak. You can also use a can of carburetor cleaner or propane (with extreme caution) to spray around hose connections and the PCV valve itself. If the engine idle speed changes (rpms increase) when you spray a specific area, you've found your leak. Finally, remove the PCV valve and shake it. You should hear a distinct rattling sound from the internal check valve. If it's silent, the valve is stuck and needs replacement.

Step-by-Step Fix

Replacing a faulty PCV valve is one of the most cost-effective repairs you can perform. Here is a detailed guide based on common practices for this type of engine component.

1. Gather Parts & Tools: Ensure you have the new PCV valve, any associated grommet or hose, and basic tools ready.
2. Locate the PCV Valve: On most modern inline engines like the Spark's, the PCV valve is typically located on the valve cover or the intake manifold. Consult your owner's manual or a vehicle-specific repair guide for the exact location.
3. Disconnect the Hose: The PCV valve will have a hose running to the intake manifold. Carefully pinch the hose clamp (which may be a spring clamp or a screw clamp) and slide it back. Gently twist and pull the hose off the valve nipple. Be careful, as older hoses can become brittle.
4. Remove the Old Valve: The PCV valve is usually pressed into a rubber grommet in the valve cover. Firmly grasp the valve body and pull it straight up and out with a twisting motion. If it's stubborn, you may need to use pliers gently on the base, but avoid crushing it.
5. Inspect the Grommet: Remove the rubber grommet from the valve cover. Inspect it for cracks, hardness, or deterioration. It is highly recommended to replace this grommet whenever you replace the PCV valve, as a leak here will cause immediate problems.
6. Install the New Grommet: Press the new rubber grommet firmly into the hole in the valve cover until it seats fully.
7. Install the New PCV Valve: Take your new valve and press it straight down into the new grommet until it snaps or seats securely. You should not be able to pull it out easily by hand.
8. Reconnect the Hose: Slide the vacuum hose back onto the nipple of the new PCV valve. Ensure the clamp is positioned correctly and tighten it to secure the connection.
9. Clear Codes and Test: Use your OBD2 scanner to clear all engine fault codes. Start the engine and let it idle. Listen for any new hissing sounds. The idle should smooth out noticeably if the PCV valve was the culprit. Take the vehicle for a test drive, ensuring it accelerates smoothly.
10. Monitor: Drive for several days and monitor if the check engine light returns. The misfire should be resolved. As one owner's experience shows, persistence pays off: "Two coils, the spark plugs (twice), and oil solenoids were replaced." Their mechanic worked through the common items before likely arriving at the root cause.

Parts and Tools Needed

• PCV Valve: An OEM or high-quality aftermarket PCV valve specific to the 2017 Chevrolet Spark. ACDelco is the common OEM supplier. (Example part number: GM original equipment #12695464, but always verify with your VIN).
• PCV Valve Grommet/Seal: Crucial for preventing vacuum leaks. (Often sold with the valve or as a separate kit).
• Spark Plugs (for related maintenance): If diagnostics point to fouled plugs. Use the exact type specified in your owner's manual (likely Iridium).
• Ignition Coil(s): Only if diagnosed as faulty. It's best to replace one at a time as needed.
• Basic Hand Tools: Set of sockets and ratchets, screwdrivers, and possibly pliers.
• OBD2 Scanner: Essential for reading and clearing diagnostic trouble codes.
• Carburetor Cleaner (for leak testing): A small can for the diagnostic spray test.

Real Owner Costs

The cost to fix a misfire varies dramatically based on the root cause and who does the work. The DIY route for the most common fix is remarkably affordable.

• DIY PCV Valve Replacement: This is the lowest-cost solution. The PCV valve and grommet typically cost between $15 and $40 for OEM-quality parts. If you choose to replace the spark plugs at the same time as preventative maintenance, add another $30-$60 for a set of four high-quality iridium plugs. The total DIY cost for addressing the core issue is often under $100, as reflected by an owner's estimate: "For about $125, you can solve this problem (price includes new OEM spark plugs, two oil changes worth of oil... and a new PCV valve)."

• Professional Repair (Chasing the Misfire): If you take the vehicle to a shop with a misfire complaint, costs can escalate quickly as they perform diagnostic time and replace common items. Replacing all four spark plugs and one ignition coil at a shop can easily cost $300-$500. If multiple coils are replaced or other components like sensors are swapped, the bill can climb toward $1,000. This is the "parts cannon" approach that frustrates owners, like one who lamented sinking significant funds into their vehicle: "I've sunk about $9K... into it since then in repairs." While not all was for the misfire, it illustrates how costs can accumulate.

• Professional Repair (Correct Diagnosis): If a skilled mechanic correctly diagnoses a failed PCV valve or a simple vacuum hose leak from the start, the repair cost should be relatively low, likely in the $100-$200 range for parts and labor. The key is finding a technician who diagnoses before replacing.

Prevention

Preventing misfires, especially those linked to PCV system failure, revolves around consistent, quality maintenance. Adhere strictly to the manufacturer's recommended oil change intervals using the correct grade of oil. Consider more frequent changes if you do mostly short trips. As one owner emphasized regarding engine longevity: "Yes - changing oil every 3000 miles is key, but obviously this alone doesn't prevent oil control rings from eventually sticking." While 3,000 miles is aggressive for modern synthetics, the principle of clean oil protecting internal components like the PCV system is sound.

During every oil change, make it a habit to visually inspect the engine bay. Look for cracked, brittle, or loose vacuum hoses, particularly the one attached to the PCV valve. Listen for unusual hissing sounds at idle. When you replace spark plugs as scheduled (typically every 60,000-100,000 miles for iridium), inspect their condition. Oil-fouled plugs are a red flag pointing to a failing PCV valve or other internal wear. Proactively replacing the PCV valve every 60,000 miles or so is cheap insurance against the much more expensive problems it can cause.

What Owners Say

Real experiences from CHEVROLET owners:

Success Stories

"No mechanics will work on it saying it’s not worth the price it will be for the new engine and labor cost and that basically I need a new car. For the past month and a half I’ve taken it in to get worked on for the engine feeling like it’s shaking and throwing codes for misfiring." — Otis_The_Pony (source)

"For the past month and a half I’ve taken it in to get worked on for the engine feeling like it’s shaking and throwing codes for misfiring. Two coils, the spark plugs (twice), and oil solenoids were replaced." — Otis_The_Pony (source)

"Breaks my heart: this was his first brand new car, dreamed of owning it, worked so hard to afford it and now he’s just so whatever about it. I figure now that we have a third car he can use as a beater and the garage space to work on the WRX now is the time." — shittysecretary (source)

Owner Experiences

"Yes - changing oil every 3000 miles is key, but obviously this alone doesn't prevent oil control rings from eventually sticking. The cause of your oil consumption is stuck oil control rings." — aquapura89 (3,000 miles) (source)

"Didn’t fix the issue Took the car to the dealership rod bearing clearance test was done and it passed thy recommended replacing knock sensor with oem one." — pluto942 (source)

"Took the car to the dealership rod bearing clearance test was done and it passed thy recommended replacing knock sensor with oem one. I replaced the knock sensor and still didn’t fix the issue then after awhile I turned the car on again and it started missfiring a ton for about a minute or two then back to normal limp mode." — pluto942 (source)

Lessons Learned

⚠️ "I reflashed a couple of times in the process and still have a crazy backfire. What else can I do alone, I’m stuck between changing the TPS, MAF or the MAP sensor but all are pricey." — Active_Bookkeeper_16 (source)

⚠️ "I have replaced both VVT sensors, both O2, Spark Plugs, coil packs, both camshaft positioning sensors and valve cover gaskets. I reflashed a couple of times in the process and still have a crazy backfire." — Active_Bookkeeper_16 (source)

Pro Tips from Owners

💡 "She bought a 2017 Sonata privately here in Canada April of 2025 with 198,000 km, or 126,000 miles. Against my advice she didn’t do the research or a pre purchase inspection." — Useful_Respect3339 (source)

💡 "Against my advice she didn’t do the research or a pre purchase inspection. Shortly after the purchase I noticed the low oil pressure light would come on intermittently, so I changed the oil and filled it." — Useful_Respect3339 (source)

Real Repair Costs

"The cause of your oil consumption is stuck oil control rings. For about $125, you can solve this problem (price includes new OEM spark plugs, two oil changes worth of oil including high-quality Valvoline Restore and Protect, and a new PCV valve)." — aquapura89 (source)

"Love the car, love Hondas (last one was a 93 civic DX). I've sunk about $9K (including routine stuff like brakes, battery, and tires) into it since then in repairs, now I'm looking at spending another $1.8K to replace the rear brakes, calipers, brake lines, and rear control arms." — Powerful-Home-2554 (source)

"I really hoped to get 300k out of this car, but I really don't want to keep putting money into that I could be putting into a new car. I've always been under the impression that after stock parts wear out, I can replace them and the car would be good to go from there, but almost $10k later here I am." — Powerful-Home-2554 (source)

FAQ

Q: How long does it take to fix a misfire caused by a PCV valve? A: For a competent DIYer, diagnosing and replacing a PCV valve is often a 30-minute to 1-hour job. It requires minimal tools and is one of the simplest engine repairs. If you are also replacing spark plugs, add another 30-45 minutes.

Q: Can I drive my car with a misfire? A: It is strongly not recommended. Driving with a severe misfire can cause immediate damage. Unburned fuel can dump into the exhaust system, overheating and destroying the catalytic converter—a repair that costs over $1,000. It can also wash down the cylinder walls with fuel, accelerating engine wear. If the check engine light is flashing, this indicates a severe misfire that could damage the catalyst; you should stop driving as soon as safely possible.

Q: Is a misfire a common issue on the 2017 Spark? A: While the 2017 Chevrolet Spark is generally reliable, misfires are a common automotive issue across all brands, typically related to maintenance items. The specific causes mentioned by owners—like failing ignition coils, worn spark plugs, and PCV valve issues—are common wear-and-tear items on any modern gasoline engine as mileage accumulates.

Q: I've already replaced the coils and plugs, but the misfire came back. What now? A: This is a classic sign pointing to an underlying issue fouling the new parts. The most likely culprit, as detailed in owner reports, is a faulty PCV valve allowing oil into the combustion chamber, which quickly fouls the new spark plugs. Your next step should be a thorough diagnosis of the PCV system and a check for vacuum leaks, not throwing more coils at the problem.

Q: DIY vs mechanic—what's recommended for a misfire? A: If you are comfortable with basic tools and can follow online tutorials, diagnosing and fixing common misfire causes (spark plugs, coils, PCV valve) is very achievable DIY work. It can save you hundreds of dollars. However, if the diagnosis points to internal engine issues (like a leaking head gasket or timing problem mentioned in broader data), or if you are not confident in your skills, seeking a professional mechanic is the wise choice. A good mechanic will perform a proper diagnosis, not just a parts replacement.

Q: Could a bad MAF sensor cause a misfire? A: Yes, owners have identified this as a potential cause. A dirty or failing Mass Air Flow (MAF) sensor sends incorrect air intake data to the engine computer, leading to an improper air/fuel mixture. This can cause lean or rich conditions that result in misfires, especially under load. Cleaning the MAF sensor with proper cleaner is a simple, low-cost diagnostic step if you suspect fueling issues.