Why Is My Car Misfiring After an Oil Change? [Answered]

When we talk about our vehicles, there’s nothing more unsettling than noticing a problem right after a routine maintenance procedure. One of these issues is experiencing a car misfire right after an oil change. You might think there’s a direct connection between the oil change and the misfire, but the reality is more complicated than that.

Misfiring after an oil change is rare. A misfire is typically associated with problems in the vehicle’s fuel, air intake, or ignition systems rather than the oil system. However, there are rare instances when an oil change may cause a misfire. For example, if the oil cap is loose, a sensor isn’t properly replaced or filled with low-viscosity oil.

Well, there’s more to it, and this article highlights how a car misfiring after an oil change is related to it.

What Is an Engine Misfire?

You can think of your car engine as an orchestra. In an orchestra, every instrument must play at the right time to create beautiful music. If one instrument plays out of turn, it disrupts the harmony. A misfire in an engine is similar to this scenario.

In a car engine, several components (spark plugs, pistons, crankshaft, valves) must work together synchronously to create the ‘music’ of smooth, efficient combustion. When everything works as it should, fuel and air mix in just the right proportions, spark plugs ignite the mixture at the perfect moment, and power is produced.

But if any of these components are out of sync – like an instrument playing out of tune or at the wrong time – it leads to a misfire. That’s when an engine cylinder fails to fire correctly or doesn’t fire at all. The result can feel like a stumble or a stutter in your car’s performance.

Why a Car Misfires After an Oil Change

As mentioned, car misfires usually don’t occur due to an oil change. However, there are a few instances where this can happen as detailed below.

Loose drain plug

Picture this, you just had an oil change, and somewhere down the line, the drain plug wasn’t tightened correctly or the washer wasn’t replaced. Even as a slow drip, it might not seem much, but you could lose a fair bit of oil over time. Being a hard worker, the engine doesn’t particularly enjoy running without enough oil.

That oil is what keeps everything moving smoothly and prevents overheating. When the oil level drops, you might notice your engine feeling like it’s jerking, followed by a lack of power. This is often your first clue that a misfire is happening.

sump plug washer causing an oil leak

Oil cap missing

Just as the sump plug keeps the oil from leaking out of the bottom of the engine, the oil cap keeps the oil from being thrown from the top. Now this is a bit drastic, but if all the oil is forced out of the engine, and with the oil cap missing, it won’t take very long; the engine will overheat and begin to misfire. The only reason the oil cap would be missing is if whoever just changed the il forgot to put it back on or left it loose and it fell off.

Disconnected sensor

Now, imagine if, during the oil change, a sensor, for example, the Mass Air Flow (MAF) sensor, was removed, usually to access the oil filter, and it wasn’t put back correctly. 

The MAF sensor measures the amount of air that enters the engine. It communicates this information to the engine control unit (ECU), ensuring the perfect fuel-air blend for combustion. But if the MAF isn’t doing its job right because it’s not been plugged back in, the mixture will be off, leading to a misfire.

Low viscosity oil                                                                           

This is a direct scenario where the oil can be the culprit. Many modern engines have Variable Valve Timing (VVT) or variation of it. This system relies on oil pressure to adjust when the intake and exhaust valves open and close.

Now, if you use oil that’s too thin or ‘low viscosity,’ your VVT might not get the pressure it needs. This can cause the ECU to cut power to the engine to protect itself, which can make your engine stumble and potentially cause a misfire.

So, sticking with the manufacturer’s recommended oil is always good idea. You can also try using an additive like Seafoam before changing the oil. It helps loosen deposits and prepares your engine for the new oil, ruling out any other oil pressure-related problems.

If Its Not Oil Related What Else Can Causes a Car to Misfire

An engine misfire typically feels like a strong hiccup, causing decreased performance and your ability to drive the car properly. But the primary question is, what causes this frustrating hiccup if it’s unrelated to an oil change? First, regardless of which item below causes the problem, the engine management light will eliminate to notify you of an issue; the correct cause can then be diagnosed by using an OBDII diagnostic tool. 

Faulty spark plugs

The spark plug’s job is to ignite the fuel-air mixture in the engine cylinders, and when they are not performing, you will face a problem. If spark plugs are old, worn out, or damaged, they may not provide the necessary spark at the right time, causing a misfire.

Ignition system problems

If it’s not the spark plugs, it might be something else in the ignition system. This includes components like the ignition coil pack or distributor. Their malfunction could disrupt the timing or strength of the spark needed to ignite the fuel.

Fuel delivery issues

Your engine needs the right amount of fuel at the right time. If there is a problem with the fuel injectors, fuel pump, or even the fuel filter (which might be clogged, reducing fuel flow), this engine might not get the fuel it needs. This will consequently result in a misfire.

Air intake problems

Issues with the air intake system, like vacuum leaks or a clogged air filter, can mess up the fuel-to-air ratio. If too much or too little air is mixed with the fuel, it can cause a misfire.

Mechanical engine issues

Sometimes the problem is more mechanical. This could include low compression due to worn piston rings, valve issues, or even timing problems with the engine timing belts or chains.

How to Fix a Car That Misfires After an Oil Change?

If your car misfires after the recent oil change, the first thing you need to do is, stay calm. Then, follow this course of action to solve this issue:

  1. Check the oil plug – Start by checking underneath your car for any signs of an oil leak. If you see any oil spots, that’s your first clue. Then, take a look at the drain plug itself. It should be securely tightened – but be careful not to overtighten, as that can cause other issues. It’s also wise to check the condition of the sump plug washer; they should be replaced when an oil change is carried out and can often be blamed for an oil leak.
  2. Inspect the filters – Filters keep all the nasties out and make sure only clean fuel, air, and oil enter the engine. But they can get clogged over time, affecting the overall performance of your vehicle. Checking all three is always a good idea if your car is misfiring. Are they dirty or clogged? If yes, replace them immediately; the oil filter should has just been changed, so if it’s dirty, it’s probably a wise decision to turn the car back and question why; however, if you changed the oil yourself, you should’ve changed the oil filter at the same time. 
  3. Look for any loose components – During an oil change, most components that may have been removed will be to access the oil filter, so that’s an excellent place to start. Check whether any electrical plugs are loose or if components haven’t been reconnected. 
  4. Check Diagnostic Trouble Codes – The car’s computer system keeps track of what’s happening inside and will flag any issues it is experiencing. These are recorded as diagnostic trouble codes (DTCs). If your car is misfiring, use an OBD2 scanner to check for DTCs. 
  5. Get the car inspected – If you need clarification on where the problem lies or what the codes suggest, it might be time to call in the pros. Schedule a full car inspection with a trusted mechanic. Equally, if you didn’t perform the oil change, it will be worth returning to the mechanic for them to inspect the problem. 

Final Thoughts

As we wrap up, it is clear that maintaining a vehicle is a bit like solving a complex puzzle. While oil changes are a routine part of car maintenance, they can occasionally lead to unexpected outcomes like engine misfires.

So, when faced with a situation like ‘engine misfire following an oil change,’ approach the issue systematically. Checking the oil plug, inspecting filters, scan for diagnostic trouble codes, or resorting to a full car inspection all play a part in getting to the root cause of the problem.

My name is Tom although my friends call me Tommy. Messing around with cars and bikes has always been a hobby of mine even from a young age. So I made it my day job 17 years ago. I am a fully qualified mechanic as you would expect. I've worked in all different areas of the motor trade, valeting, panel beating, engine repairs, I'm sure you get the idea. I enjoy sharing my wealth of knowledge and experience with others, which is the reason I spend a lot of time here writing for this website.

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