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Ram 1500 (175k miles) running rough with P0300-P0308: Multiple cylinder misfires and intermittent issues

Model: Ram 1500 Fault Code: P0300 Posted: 2006-09-18 19:27

My 2000-2006 Ram 1500 with a 5.2L V8 engine has started running roughly after being smooth for years. The truck recently developed an intermittent misfire issue — the check engine light came on immediately upon restarting, and the engine ran rough even though it wasn't cold. After diagnostics, I received DTCs P0300 through P0308 indicating multiple cylinder misfires. The last tune-up was performed at 150k miles, with new spark plugs and ignition wires installed within the past six months. The truck has generally run smoothly until now. Despite replacing key components like plugs, cap, rotor, and wires, the problem persists intermittently — sometimes running rough on multiple cylinders (especially #3, #8), other times smoothing out for short periods. I'm considering a coil pack replacement as suggested by several users, especially since the 5.2L V8 engine is known to have issues with coil degradation over time due to heat exposure and aging. I plan to install a new coil on Tuesday (9/26) and will update here on results. I'm also checking fuel pressure, injector pulse signals, compression, and vacuum leaks as recommended. The previous parts used were Bosch platinum plugs and wires, with Advance Auto lifetime cap and rotor. I've since switched to Autolite plugs and Exact brand ignition wires. Any additional insights or troubleshooting steps for this specific engine and fault code pattern would be greatly appreciated.

Related fault codes
P0300P0301P0302P0304P0305P0306P0307P0308
Comments (11)
Anonymous 2006-09-19 08:52

What engine configuration do you have? If it's a 5.2L or 5.9L V8, the issue is likely related to the ignition coil pack. Over time, especially at 175k miles, coils can swell and crack due to heat exposure — even if other components like plugs, wires, cap, and rotor are in good condition. I've seen this commonly at dealerships; replacing the coil often resolves multiple cylinder misfires (P0300-P0308). Good luck — please update on results.

Anonymous 2006-09-19 21:00

Thanks for the tip! The issue is indeed intermittent — sometimes running rough across 3–4 cylinders, other times smooth. In the last half-hour today, it ran smoothly again. I hate intermittent problems, but I'm now planning to replace the coil by Tuesday (9/26). Will update once installed. Thanks again!

Anonymous 2006-09-20 06:27

What engine are you running? The 5.2L V8 is common in Ram 1500s — could be a key factor in diagnosing misfires.

Anonymous 2006-09-25 19:13

Confirmed: 5.2L small block V8. I'm expecting to install the new coil on Tuesday, 9/26. The issue remains intermittent, but I'm hopeful it will resolve after the replacement. Will update with results.

Anonymous 2006-09-26 10:58

What spark plug and ignition wire brand were used during the last tune-up?

Anonymous 2006-10-07 08:06

I have the same issue on my 1996 Ram 1500 4x4 with a 5.2L engine. The problem started after a major drive train repair — I noticed backfiring, misfires, and a check engine light. After resetting the ECU by disconnecting the negative battery cable for 60 seconds, everything seemed fine until last week when symptoms returned. Now it's worse: severe misfires, especially in overdrive, making driving unsafe. I've replaced plugs, cap, rotor, wires, and even tried a new coil. Two separate OBD2 scanners both show multipoint misfire on cylinders 3 and 8. Could this be a faulty ECU? Any advice would be much appreciated.

Anonymous 2006-10-07 08:34

Unlikely to be the ECU — start by checking injector pulse signals for cylinders 3 and 8, as they're close in firing order. Verify fuel pressure is within range. Ensure ignition wires are properly routed (especially since #3 and #8 are adjacent). Also check compression and vacuum leaks. Make sure high-quality parts were used originally — the brand of plugs and wires matters significantly. What brand did you use for wires, distributor cap, and rotor?

Anonymous 2006-10-07 09:53

Original setup: Bosch platinum plugs and wires; Advance Auto lifetime cap and rotor. I've now switched to Autolite plugs and Exact brand ignition wires. I'm going to try wrapping the wires with crinkle wrap (as recommended on Dodge's official site) and re-routing them according to proper guidelines — some say this is a fussy detail but critical for performance.

Anonymous 2006-10-08 11:14

For a 5.2L V8, consider using Champion non-platinum spark plugs — they often perform better than platinum in older engines due to reduced wear and better combustion characteristics.

Anonymous 2006-10-08 16:31

I've had issues with Champion plugs in other vehicles — the problem was eventually traced to a faulty injector. Jeff, you might want to check the everything else forum for similar cases. Thanks for the input!

Anonymous 2006-10-08 18:27

Congrats on resolving your issue! This thread is helpful for others facing similar misfire problems.