High-Probability Causes:
* Throttle Position Sensor (TPS): A faulty TPS provides inaccurate information to the engine control unit (ECU), leading to poor idle and erratic fuel delivery. This is a very common cause of the symptoms you describe. Testing involves checking the sensor's voltage output with a multimeter while manipulating the throttle.
* Mass Airflow Sensor (MAF): The MAF measures the amount of air entering the engine. A dirty or malfunctioning MAF sensor provides incorrect information to the ECU, resulting in a rich or lean fuel mixture, causing rough idling and hesitation. Cleaning it (carefully, with MAF sensor cleaner) is often the first step, but replacement may be necessary.
* Fuel Injectors: Clogged or faulty fuel injectors can lead to an uneven fuel spray, causing rough idling and poor performance. They might need cleaning or replacement. A fuel injector cleaner additive in the fuel tank might be a temporary fix if they are only slightly clogged.
* Fuel Pump: A weak fuel pump may not provide sufficient fuel pressure under load (when accelerating), causing the engine to stumble or stall. Fuel pressure testing is necessary to confirm this.
* Ignition System: Problems with the ignition coil, spark plug wires, distributor cap, or rotor (if equipped) can lead to misfires, resulting in rough idling and poor performance. Inspect these components for wear, cracks, or corrosion. Spark plug condition is crucial.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the proper functioning of various engine components, leading to rough idling and poor performance. Inspect all vacuum hoses for cracks or disconnections.
* Computer/ECU issues: While less common, a malfunctioning ECU can cause a variety of driveability problems. This is typically diagnosed through professional testing.
Troubleshooting Steps (in order of easiest/cheapest to most involved):
1. Check Engine Light (CEL): Does the CEL illuminate? If so, have the codes read using an OBD-II scanner (although 1994 might be OBD-I, requiring a different scanner). The codes can pinpoint the problem.
2. Visual Inspection: Examine all vacuum hoses, spark plug wires, distributor cap (if applicable), rotor, and ignition coil for any visible damage.
3. Clean the MAF Sensor: Use a specialized MAF sensor cleaner (NOT regular carb cleaner) to gently clean the sensor element. Let it dry completely before reinstalling.
4. Check and replace the air filter: A clogged filter restricts airflow, causing similar symptoms.
5. Check Spark Plugs and Wires: Inspect the spark plugs for wear, fouling, or damage. Replace them if necessary. Similarly, inspect the spark plug wires for cracks or damage.
6. Fuel pressure test: If you suspect a fuel pump issue, a fuel pressure test is essential. This requires a fuel pressure gauge.
7. Throttle Body Cleaning: A dirty throttle body can impede airflow and contribute to rough idling. Clean it thoroughly using throttle body cleaner. (Disconnect the battery negative terminal first!)
Important Notes:
* Safety First: Work in a well-ventilated area when dealing with fuel and automotive chemicals.
* Professional Help: If you're not comfortable performing these checks yourself, take your vehicle to a qualified mechanic. Improper diagnosis can lead to further damage.
* Year-Specific Issues: 1994 Fleetwood Broughams are older vehicles and might have specific issues related to their age and components. Consulting a repair manual specific to your year and model is highly recommended.
By systematically investigating these areas, you'll increase your chances of identifying the root cause of your Fleetwood's problems. Remember to document your findings as you go.
