I recently noticed my truck has a slight misfire when accelerating heavily onto the expressway and it idles rough. It doesn’t sound too bad, but the truck shakes a little at idle. Above idle and below high RPM, it runs strong and smooth, making it hard to replicate the issue, and it doesn’t misfire long enough to throw a code. It starts fine but cranks a second or two longer than it used to before starting. Fuel mileage hasn’t changed much.
The truck has 180k miles, with no issues until now. I’ve done regular fluid changes and mostly highway miles, with no other repairs needed. The plugs were last changed around 150k miles.
There are no engine lights, but my scanner picked up a P0316 code. I use 2-3 full tanks of fuel a week, so I don’t think it’s bad fuel. This issue has probably been getting worse over the past few weeks.
Where should I start with troubleshooting? Some parts that might cause a P0316 code, like coils, EGR, and crank position sensor, are also parts that should be replaced as part of regular maintenance. I don’t want to just replace parts randomly, but if they need replacing anyway, it can’t hurt.
P0316 indicates that your car’s computer has detected an engine misfire. Although a faulty or dirty spark plug can cause this misfire and trigger the code, replacing the spark plugs is typically the first step to address it. However, if you also notice metal in the cylinder and knocking sounds along with the misfire code, it suggests a more serious issue that changing the spark plugs alone won’t resolve.
The P0316 code indicates a misfire during the initial startup phase. While it’s tempting to replace parts that might be due for service, a more systematic approach is recommended.
Potential Causes for P0316:
Spark Plugs and Ignition Coils: Common culprits for misfires. Given the mileage, these parts might be due for replacement.
Fuel Injectors: Worn or clogged injectors can contribute to misfires, especially during startup.
Crankshaft Position Sensor (CKP) or Camshaft Position Sensor (CMP): These sensors are crucial for engine timing and can cause misfires if faulty.
Compression Issues: Low compression in a cylinder can lead to misfires, especially during startup.
Vacuum Leaks: Small vacuum leaks can affect engine performance and contribute to misfires.
Troubleshooting Steps:
Inspect Spark Plugs and Ignition Coils: While they might be due for replacement, inspect them for wear or damage.
Check for Vacuum Leaks: Visually inspect hoses and connections for any cracks or loose fittings.
Perform a Compression Test: This will help determine if there are any compression issues in the cylinders.
Check Fuel Pressure: Ensure the fuel pump is delivering adequate pressure.
Inspect Fuel Injectors: Look for signs of wear or clogging.
Verify Crankshaft and Camshaft Sensor Operation: These sensors are crucial for engine timing.
General Maintenance:
Given the age of your truck, it’s likely that some components are nearing the end of their service life. Replacing spark plugs, ignition coils, and the air filter is generally recommended around 100,000 miles.