Engine misfiring? Get your car inspected at your home or office.

Our certified mechanics come to you · Backed by our 12-month, 12,000-mile warranty · Get a fair and transparent estimate upfront

GET A QUOTE Backed by 12-month, 12,000-mile guarantee
Red-stars EXCELLENT RATING ON

Engine is misfiring Inspection Service

When an engines misfires, it’s usually readily apparent to the driver from the stuttering and jerking produced by the engine when one or more cylinders fails to fire properly, either because of ignition- or fuel-related issues. It is accompanied by a loss of power in direct proportion to the severity of the misfire.

It can be tricky for to track down the problem if the misfire only occurs under certain circumstances, for example, under load. Not all misfires occur across the operating spectrum.

For older vehicles:

On older, carbureted vehicles, the culprit will almost certainly be in the ignition system as older vehicles lack many of the sophisticated sensors that can cause a misfire. A vacuum leak or a faulty fuel pump can also cause this symptom as well. The first thing the mechanic will do is determine which cylinder or cylinders is misfiring, and the spark plug color is probably the best way to tell. The guilty plug will most likely be grayer than the others, which should tend toward brown coloring. If needed, the spark plug can be replaced.

The next step would be checking the wiring to that plug for cracks and deterioration, and replace as necessary.

For most modern vehicles:

In modern cars, misfiring will invariably be accompanied by a Check Engine light. In fact, checking for efficient combustion was the primary reason the U.S. government introduced the rules for OBD-II (on-board diagnostics, second generation). It was part of the push toward cleaner exhaust emissions.

A code reader will tell you which cylinder is to blame, but it may not say whether it is a problem relating to the injector serving that cylinder or the systems delivering the ignition spark. As with older vehicles, a look at the wires and spark plugs is a good idea. Checking them in the dark will sometimes reveal errant spark tracking, as will spraying them with a fine water mist.

One way mechanics check which spark plug is failing to hold its own is by running the engine at an idle speed high enough to produce the misfire, then removing leads from the coilpack (the unit that looks like the distributor we are used to seeing in older vehicles ) one by one. Most removals will cause a profound change in idling performance, but a defective wire will not. That will suggest that it’s either the spark plug or the coil serving that cylinder at fault. If a new spark plug at that cylinder does not remove the stumble, the mechanic may need to replace the coil pack or the wires as a set.

If it isn’t an ignition issue, then the injectors will need to be checked. A mechanic uses a multimeter to check the resistance value at each injector. It may be a bit difficult to reach them, sometimes requiring the removal of an engine cover and the intake manifold. The mechanic disconnects the injector, then touches the multimeter probes to the two connector prongs to read the value, in Ohms. If any of the injectors read outside of the specified values, they will need to be replaced.

Along the same lines, a fuel pump starting to go bad can also cause misfires or similar issues and can be diagnosed with a fuel pressure check of the entire system with the appropriate equipment. This should only be done by a qualified mechanic as the fuel system is highly pressurized and of course, fuel is flammable.

Common reasons for this to happen:

  • Faulty spark plugs or wires
  • Faulty ignition coil
  • Broken piston rings
  • Burnt or bent valves
  • Broken valve springs
  • Camshaft worn out
  • Fuel injector is not working

What to expect:

A top-rated mobile mechanic will come to your home or office to determine the source and cause of the misfiring engine, and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.

How important is this service?

A misfiring engine is accompanied by a loss of power, which makes this issue a critical one to correct promptly. Book a mechanic to perform a thorough inspection as soon as possible.

Fast and easy Engine is misfiring Inspection service at your home or office.

GET A QUOTE FOR YOUR CAR
Backed by 12-month, 12,000-mile guarantee

Recent Engine is misfiring Inspection reviews

Excellent Rating


YourMechanic Engine is misfiring Inspection Service

Average Rating

4.5/5

Number of Reviews

117

Rating Summary
105
7
2
1
2
105
7
2
1
2

Brikk

14 years of experience
146 reviews
Brikk
14 years of experience
Brikks was excellent. On time, really helpful and did a great job helping me work out the problems. Will definitely use him again
2004 JAGUAR S-TYPE - ENGINE IS MISFIRING - CHARLOTTE, NORTH CAROLINA

James

26 years of experience
151 reviews
James
26 years of experience
James arrived a little earlier than our scheduled appointment, so we had some time to chat and go into detail about the car's history and so he could provide a more thorough diagnosis of my car. James was very polite, friendly, and a great conversationalist during the appointment. Related to the actual appointment, James was very thorough in his diagnosis of my car and even helped me understand a bit more about my car and what it needed so I could take that information and learn from it. During his report, he determined what was wrong with my car (a bad injector) and even went beyond to determine things that could come up as potential issues and how to remedy them. Overall, the experience was very positive and I'm glad that I went ahead and setup an appointment for James to diagnose my car. If I had someone that needed a mechanic or someone to diagnose their car, James would likely be the first person that came to mind.
1996 NISSAN 240SX - ENGINE IS MISFIRING - CASSELBERRY, FLORIDA

Patrick

29 years of experience
712 reviews
Patrick
29 years of experience
Patrick is reliable and very knowledgeable. I would always recommend Patrick to anyone considering work on their car
2006 MITSUBISHI RAIDER - ENGINE IS MISFIRING INSPECTION - AUSTIN, TEXAS

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com