2000 Chrysler Grand Voyager V6 (3.3L) with P0171 Code: Hard to Start, Rough Idle and Hesitation - How to Fix?

Check fuel pressure, EGR valve operation, oxygen sensor function, thermostat performance, spark plug condition, and exhaust leaks. Has any work been done recently? Please update your progress—good luck and stay posted! Jeff

No repairs have been performed recently. I replaced the upper intake gasket, throttle body gasket, and EGR valve gasket. The hesitation during acceleration has improved—but it's still worse when the A/C is on. I suspect the IAC valve or MAP sensor might be at fault. Any suggestions? Thanks for your input!

Was the P0171 code present before replacing the intake gasket?

Yes, the code was there before. I replaced the upper intake gasket while also fixing a cracked PCV hose. Today, I replaced the oxygen sensor after the catalytic converter. The hesitation has improved—but hard starts and rough idling persist. The scan still shows a pending P0171. Thanks for your help!

Difficulty starting and a P0171 code may indicate low fuel pressure. Have the spark plugs been replaced before? If not, that could be a contributing factor.

If it were truly low fuel pressure, I’d expect symptoms on both sides of the engine—not just one side. The last plug replacement was about 40K miles ago, so that’s not likely the root cause.

By 'both sides,' I mean both banks of the engine. A V6 only has two oxygen sensors: one before and one after the catalytic converter—bank 1 (front) and bank 2 (rear). The PCM uses this layout to generate P0171 for a lean condition in Bank 1. A three-sensor setup (one per side of the engine) is required to trigger a P0174 code. In practice, many mechanics generate P0171 when performing fuel injection cleaning—by removing the fuel pump relay while the engine runs to drain lines before testing. If the engine is hot and continues running for 30 seconds or more, this code often appears as a flag indicating low fuel pressure. To test EGR: remove it from the intake manifold, install a cardboard gasket to temporarily seal it, then reattach. If drivability improves—especially with reduced hesitation—EGR is likely the culprit. Otherwise, use a fuel pressure gauge during a road test to verify consistent pressure. Fuel pump pressure can drop as the pump heats up. Keep me posted! Jeff

Thanks for your detailed input. This evening, while driving, the vehicle began sputtering and barely reached 20 mph. I heard popping noises—almost like a backfire. The hesitation is severe when pressing the accelerator, especially in both park and drive. In response to your advice: the oxygen sensor I replaced was after the catalytic converter. Would that be considered Bank 1 Sensor 2? I checked the resistance of the sensor before the cat—it read normally, so it’s likely fine. I’m now leaning toward a failing fuel pump.

No—the oxygen sensor after the catalytic converter is Bank 1 Sensor 2. The one ahead of it would be Bank 1 Sensor 1. Ohm readings are not an accurate way to test oxygen sensors. A V6 engine only has two oxygen sensors—no third sensor unless in California emissions setups, and even then, only two are typically used. Check your fuel pressure—it’s the most likely root cause of this issue.