Hobbies Cars & Motorcycles Troubleshooting Engine Driveability Problems: Surging or Misfiring Share PINTEREST Email Print Paul Bradbury / Getty Images Cars & Motorcycles Cars How Tos Buying & Selling Basics Reviews Tools & Products Classic Cars Exotic Cars Corvettes Mustangs Tires & Wheels Motorcycles Used Cars SUVs Trucks ATVs & Off Road Public Transportation By Matthew Wright Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. our editorial process Matthew Wright Updated December 03, 2018 Whatever the cause, if your car's engine is misfiring or surging, it will prompt error codes to appear in your OBD-II Diagnostics system. These codes can cause you to fail your local vehicle inspection, or at the very least can result in that alarming orange glow to appear on your dashboard: the Check Engine Light. The good news is that, in many cases, an engine that is running poorly can be repaired for very little money. Regular Maintenance Performing maintenance tasks like replacing worn spark plugs, inspecting plug wires, or even replacing an old, partially clogged fuel filter can make a huge difference in how well your engine is running. This can also save you a bundle of money, because even an hour of diagnostic time at your local repair shop can put the smackdown on your wallet. But if you've kept up with your maintenance and your engine is still acting up, read on for possible causes and fixes. Engine Misfire While Moving First, let's pinpoint exactly what's going on. We're not talking about a knocking engine or one that idles rough or stalls. We're talking about engines that start easily and accelerate smoothly, but then, after a few minutes at a steady speed, either surge in speed or misfire, causing the car to "buck." If that's your experience, then there are a number of things you can check out first before heading to a mechanic. Diagnostics and Fixes The list of symptoms and possible causes below should help you get a better idea of what's causing your engine to act up. If you see a symptom that looks familiar, read on to find out what a possible fix can be. Nothing is set in stone, of course, but a cheap fix is always preferable to an expensive repair bill. Look over all of the symptoms and fixes to be sure you're working with the one that most closely describes your situation. If you have a carburetor (there are still a few out there), the choke may not be set properly or may not be working correctly.The fix: Check the choke plate and make sure it is opening completely.The engine may be running too hot.The fix: Check and repair the cooling system.The fuel pressure regulator may be operating at low pressure.The fix: Check fuel pressure with a fuel pressure gauge. If low, take it to a mechanic, as repairing or replacing a fuel pressure regular is generally not a DIY job. The ignition timing may be set wrong.The fix: Adjust ignition timing.There is a problem with the ignition system, causing a weak spark.The fix: If your vehicle has them, check and replace distributor cap, rotor, ignition wires, and spark plugs. Otherwise, have the coil packs looked at.There may be a fault in the computerized engine control system. Check engine control systems with a scan tool. Have a mechanic test the circuits and repair or replace components as required, since this is generally not a DIY job.The fuel filter may be partially clogged. This is an easy fix!The fix: Replace the fuel filter.Torque converter (automatic transmission only) may not be locking at the right time, or it may be slipping.The fix: Check lock up circuit or have the torque converter replaced. This is not a DIY job.There may be a vacuum leak.The fix: Check and replace vacuum lines as required.Possible internal engine problems.The fix: Check compression to determine engine condition.EGR valve may be stuck open.The fix: Replace EGR valve.Drive axles may be loose or worn.The fix: Check and replace CV/universal joints as required.The fuel injectors may be dirty.The fix: Clean or replace fuel injectors.