Engine Related:
* Spark Plugs and Wires: Worn, damaged, or improperly gapped spark plugs, along with cracked or loose spark plug wires, can cause a misfire, leading to shaking. This is a common and relatively inexpensive fix.
* Ignition Coil(s): A failing ignition coil can prevent one or more cylinders from firing correctly. This will also cause a misfire and shaking.
* Distributor (if applicable): Older vehicles may have distributors. Worn or damaged distributor components (rotor, cap) can cause similar issues to bad spark plugs and wires.
* Fuel Injectors: Clogged or malfunctioning fuel injectors can lead to an uneven fuel/air mixture, causing rough idling and shaking.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the engine's timing and fuel delivery, resulting in a rough idle. These can be tricky to find.
* Engine Mounts: Worn engine mounts allow excessive engine movement, which can manifest as shaking, especially at idle. This is more likely to feel like a general vibration rather than a specific shaking related to engine misfires.
* Throttle Body: A dirty or faulty throttle body can affect the air/fuel mixture, leading to rough idle. Cleaning it is often a simple solution.
* PCV Valve: A clogged Positive Crankcase Ventilation valve can build up pressure in the crankcase, affecting engine performance and causing a rough idle.
Transmission Related (Less Likely at Idle, but possible):
* Transmission Mounts: Similar to engine mounts, worn transmission mounts can contribute to shaking, though this is more noticeable during acceleration and driving.
Other Potential Issues:
* Low Engine Oil: Low oil level can cause various engine problems, including rough idling. Check your oil level immediately.
* Balance Shaft (If Applicable): Some engines have balance shafts that help reduce vibrations. Problems with these can cause shaking, though this is less common.
Troubleshooting Steps:
1. Check Engine Oil: The simplest first step is to check your oil level. Low oil is a serious problem.
2. Check the Engine Codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the vehicle's computer. These codes can provide valuable clues.
3. Listen Carefully: Pay attention to the sound the engine is making. A ticking, clicking, or knocking sound might point to a specific component.
4. Visual Inspection: Look for any visible signs of damage or wear on engine components, such as loose wires, cracked hoses, or leaks.
5. Start with the Cheap and Easy: Begin by checking and replacing spark plugs and wires. This is often the cause and a relatively inexpensive fix. Then move on to cleaning the throttle body.
If you're not comfortable performing these checks yourself, it's best to take your van to a qualified mechanic for diagnosis and repair. Providing them with any information you gather during your troubleshooting will help them efficiently pinpoint the problem.
