1. Immediate Action:
* Stop driving as much as possible: Continued driving with a misfire can severely damage the catalytic converter.
* Get it to a mechanic ASAP: This is the safest and most efficient way to diagnose and repair the problem.
2. Preliminary Checks (if you have some mechanical experience and are comfortable doing so):
* Check your gas cap: A loose or faulty gas cap can trigger a misfire code. Ensure it's properly tightened.
* Inspect the air intake system: Look for any cracks, loose connections, or blockages in the air filter, intake hoses, or mass airflow sensor (MAF) Clean the MAF sensor carefully with MAF sensor cleaner (following the instructions precisely).
* Visual inspection of ignition system: Look for obvious signs of damage to spark plug wires (cracks, fraying). Inspect the ignition coil packs for cracks or damage. A failing coil pack is a common cause of misfires in this generation of Trailblazers.
3. Diagnostic Trouble Codes (DTCs):
* Obtain DTCs: The flashing check engine light means there's a misfire detected. You need the specific codes to pinpoint the problem. You can:
* Use an OBD-II scanner: These are relatively inexpensive and available at most auto parts stores. The scanner will provide the numerical codes.
* Visit a mechanic: They have professional scanners and can quickly read the codes.
Common Causes Based on Symptoms:
The combination of rough running, sputtering, and a flashing CEL strongly suggests a misfire in one or more cylinders. Possible causes include:
* Spark Plugs: Worn, fouled, or damaged spark plugs are a frequent culprit.
* Ignition Coils: These can fail, causing misfires in the cylinder(s) they serve. They are particularly vulnerable on the Trailblazer.
* Worn or damaged spark plug wires: Cracks or damage in the wires can prevent proper spark delivery.
* Fuel Injectors: A clogged or faulty fuel injector can prevent sufficient fuel delivery to a cylinder.
* Crankshaft Position Sensor (CKP): A failing CKP sensor can disrupt ignition timing.
* Mass Airflow Sensor (MAF): A faulty MAF sensor can lead to a lean or rich fuel mixture.
* Camshaft Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP can cause misfire problems.
Important Note: A flashing CEL generally signifies a more severe problem needing immediate attention compared to a steady CEL. Attempting to diagnose and repair this issue yourself without experience can be dangerous. A professional mechanic can use the DTCs along with other diagnostic tools to quickly identify and fix the underlying cause.
