The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2016 Chrysler 300C - Engine Misfire and Rough Idle after Cold Start

0

Mike T. · rep 0 · May 25, 4:21 AM · 1 replies · solved · Question

Vehicle: 2016 Chrysler 300C HEMI

My 2016 Chrysler 300C (5.7L HEMI) has developed a really annoying issue. After a cold start, especially in the morning, the engine idles very rough, almost like it's sputtering. The check engine light comes on and flashes sometimes, then stays solid. When I checked the codes, I'm getting P0301 and P0300, indicating a misfire in cylinder 1 and random/multiple misfires.

Once the engine warms up, the rough idle smooths out a bit, but I can still feel a slight vibration. Acceleration also feels a little sluggish. I've tried replacing the spark plugs and ignition coil for cylinder 1, but the problem persists. Could it be something else like an injector or even a lifter issue? Any thoughts on what to check next?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:21 AM

0

ClearTheCode admin answer:

Experiencing misfires and a rough idle on your 2016 Chrysler 300C, especially with P0301 and P0300 codes, points to a specific problem area. While you've already addressed spark plugs and the coil on cylinder 1, the issue can stem from several other engine components. The flashing check engine light indicates a severe misfire that could damage the catalytic converter, so it's important to address this promptly.

Here are the common causes and diagnostic steps:

  1. Fuel Delivery:
    • Clogged Fuel Injector: A dirty or failing fuel injector for cylinder 1 could be delivering an insufficient or incorrect spray pattern, leading to a misfire. You could try a fuel system cleaner, but testing the injector's flow and pattern is more definitive.
    • Low Fuel Pressure: A failing fuel pump or clogged fuel filter could lead to overall low fuel pressure, causing multiple cylinder misfires (P0300).
  2. Air/Vacuum Leaks: Unmetered air entering the engine can lean out the air-fuel mixture, causing misfires. Check for vacuum leaks around the intake manifold, PCV valve, and vacuum lines, especially when the engine is cold.
  3. Compression Issues:
    • Valve Train Problems: The 5.7L HEMI engines, particularly those with the Multi-Displacement System (MDS), can be prone to lifter or camshaft lobe wear. A failing lifter can cause a valve to not open or close correctly, leading to a loss of compression and misfire. This often presents itself more noticeably when cold.
    • Head Gasket/Valve Issues: Less common, but a failing head gasket or burnt valve could also cause low compression in a cylinder.
  4. Sensor Malfunctions: A faulty oxygen sensor, MAF sensor, or even a coolant temperature sensor could send incorrect data to the PCM, leading to an improperly calculated air-fuel mixture and subsequent misfires.

When to See a Shop: Since you've already replaced basic ignition components, it's time for a professional diagnosis. A mechanic can perform a compression test, leak-down test, fuel pressure test, and visually inspect for vacuum leaks. They can also use specialized diagnostic equipment to monitor fuel injector pulse widths and live data from various sensors. If lifter or camshaft issues are suspected, further internal engine inspection may be required.

Menu

Help & account