The fact that it runs fine at idle and then dies under acceleration points to a more serious issue related to fuel delivery or ignition under load. Here are some more likely culprits:
* Crankshaft Position Sensor (CKP): A failing CKP sensor prevents the engine from getting the correct timing signal, leading to stalling, especially under load.
* Throttle Position Sensor (TPS): A malfunctioning TPS gives the engine computer inaccurate information about the throttle position, causing erratic fuel delivery.
* Fuel Pump: The fuel pump might be weak or failing, unable to provide sufficient fuel under the increased demand of acceleration. This is particularly likely if it idles fine but struggles under load.
* Fuel Filter: A clogged fuel filter can restrict fuel flow, producing similar symptoms.
* Mass Airflow Sensor (MAF): A dirty or failing MAF sensor will provide incorrect air/fuel mixture information, which will lead to stalling or rough running.
* Ignition System Components: Problems with the ignition coil, spark plug wires, or spark plugs themselves could cause misfires under load, leading to stalling.
Troubleshooting Steps:
1. Check the obvious: Before diving into sensors, ensure your battery terminals are clean and tight. A bad connection can cause intermittent issues.
2. Fuel pressure test: This is crucial. A mechanic can test the fuel pressure at idle and under load to determine if the fuel pump is supplying enough fuel.
3. Inspect and test other sensors: Check the CKP and TPS sensors. A mechanic can usually test these with a scanner or multimeter.
4. Check the MAF sensor: Clean the MAF sensor carefully (with MAF sensor cleaner ONLY – do not use anything else), this is a common problem that can cause poor running conditions.
5. Ignition system check: Inspect spark plug wires, plugs, and the ignition coil for cracks, damage, or signs of wear.
6. Fuel filter replacement: It’s inexpensive and a good preventative measure.
The Downstream O2 Sensor: While you *should* eventually replace the downstream O2 sensor (especially if the code keeps returning), it's highly unlikely to be the root cause of your Jeep's current problem. Focus on the fuel delivery and ignition systems first. Ignoring a failing downstream O2 sensor long-term might impact emissions and fuel economy, but it won't directly cause your engine to die when accelerating.
It's strongly recommended to take your Jeep to a mechanic who can properly diagnose and repair the issue. Attempting to fix this without proper tools and diagnostic equipment could lead to further damage or wasted time and money.
