Uploaded August 2026 | Updated September 2026, 1 day ago
If your engine misfires only under load, but seems fine at idle, that’s a major clue. In this video, I explain why a car can run smoothly in the driveway but start jerking, shaking, or flashing the check engine light when you accelerate, climb a hill, or drive at highway speed. We’ll go through the most common causes, including worn spark plugs, weak ignition coils, coil boots, fuel delivery problems, clogged injectors, vacuum leaks, boost leaks, and low compression. I’ll also explain how to diagnose the problem in the right order so you don’t waste money replacing random parts.
To make diagnosis easier, I’ve prepared a list of useful tools in the description, including an OBD2 scanner with live data, spark plug socket, torque wrench, spark tester, multimeter, fuel pressure gauge, smoke machine, and compression tester.
Tools to Get the Job Done:
amzn.to/3RXKM27 - All-In-One OBD2 Scanner
amzn.to/3Q2X0Gk - Spark Plug Socket Set
amzn.to/3SqWl20 - Good Torque Wrench
amzn.to/3S8H8Ta - Feeler Gauges Set
amzn.to/43SlHID - High Performance Dielectric Grease
amzn.to/4eimYxk - Inline Spark Plug Tester
amzn.to/3PY2Mcl - Digital Multimeter Tester
amzn.to/4vOJwgG - Fuel Pressure Tester Kit
amzn.to/49UWeBZ - Automotive Smoke Machine EVAP Vacuum Leak Tester
amzn.to/4xqzGTs - Petrol Engine Cylinder Compression Tester Kit
Timecode:
00:00:00 - Short intro
00:00:51 - What does “under load” actually mean?
00:01:30 - Worn spark plugs
00:02:09 - Weak ignition coil or coil boot
00:02:50 - Fuel delivery problem
00:03:35 - Dirty or failing fuel injector
00:04:12 - Vacuum leak or intake leak
00:04:48 - Compression problem
00:05:22 - Sensor or air-fuel control problem
00:05:50 - How to diagnose a misfire under load.
00:06:56 - Tools that help diagnose and fix the issue.
Affiliate Disclosure: Some links in this description are Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you. Thanks for supporting the channel!
If your engine misfires only under load, but seems fine at idle, that’s a major clue. In this video, I explain why a car can run smoothly in the driveway but start jerking, shaking, or flashing the check engine light when you accelerate, climb a hill, or drive at highway speed. We’ll go through the most common causes, including worn spark plugs, weak ignition coils, coil boots, fuel delivery problems, clogged injectors, vacuum leaks, boost leaks, and low compression. I’ll also explain how to diagnose the problem in the right order so you don’t waste money replacing random parts.
To make diagnosis easier, I’ve prepared a list of useful tools in the description, including an OBD2 scanner with live data, spark plug socket, torque wrench, spark tester, multimeter, fuel pressure gauge, smoke machine, and compression tester.
Tools to Get the Job Done:
amzn.to/3RXKM27 - All-In-One OBD2 Scanner
amzn.to/3Q2X0Gk - Spark Plug Socket Set
amzn.to/3SqWl20 - Good Torque Wrench
amzn.to/3S8H8Ta - Feeler Gauges Set
amzn.to/43SlHID - High Performance Dielectric Grease
amzn.to/4eimYxk - Inline Spark Plug Tester
amzn.to/3PY2Mcl - Digital Multimeter Tester
amzn.to/4vOJwgG - Fuel Pressure Tester Kit
amzn.to/49UWeBZ - Automotive Smoke Machine EVAP Vacuum Leak Tester
amzn.to/4xqzGTs - Petrol Engine Cylinder Compression Tester Kit
Timecode:
00:00:00 - Short intro
00:00:51 - What does “under load” actually mean?
00:01:30 - Worn spark plugs
00:02:09 - Weak ignition coil or coil boot
00:02:50 - Fuel delivery problem
00:03:35 - Dirty or failing fuel injector
00:04:12 - Vacuum leak or intake leak
00:04:48 - Compression problem
00:05:22 - Sensor or air-fuel control problem
00:05:50 - How to diagnose a misfire under load.
00:06:56 - Tools that help diagnose and fix the issue.
Affiliate Disclosure: Some links in this description are Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you. Thanks for supporting the channel!
