Dakota - Acceleration Stumble & Codes P0201/P0300 🛠️

Thanks for the detailed history — that helps a ton. On your Dakota, a P0201 is a cylinder 1 injector circuit fault, and the flashing light with P0300 (random misfire) fits a hard misfire on one hole that’s upsetting the whole engine. Because you’ve already cleaned injectors and ruled out vacuum leaks, we need to focus on cylinder 1’s injector electrical circuit and coil/spark under heat-soak.

Quick questions before we dive in

• 🔎 When it stumbles, can you confirm if it’s worse after a short hot soak (like 5–20 minutes) versus cold? Sounds like it.
• 🔧 Are your spark plugs OE-spec copper and gapped to 0.040 in, and did you replace the plug wire/coil-on-plug boot for cylinder 1 at the same time?

What typically fails on your Dakota

• 🧰 Injector #1 circuit issue: broken wire or poor terminal tension at the injector plug. Heat soak makes it open intermittently.
• 🧰 Coil/plug/boot fault on cylinder 1: under-load misfire once hot. Even new plugs can misfire if the boot is carbon-tracked. Carbon tracking = lightning-like black line.
• 🧰 Grounds and ASD relay feed: a weak ground or feed can trigger injector circuit faults.

Targeted tests you can do now

• 🔌 Identify cylinder 1: front cylinder on the passenger side (bank 1, cylinder order front-to-back on that bank).
• 💡 Swap test: swap injector #1 with injector #3. Clear codes, drive hot.
  • If the code changes to P0203 or misfire follows cylinder 3, the injector is the issue despite cleaning.
  • If P0201 stays, the wiring/PCM driver or coil/plug is at fault.
• 🧪 Noid light test (a noid light is a small tester that shows if the injector is pulsing): unplug injector #1, plug in noid light, crank or idle.
  • Flashing = PCM is commanding the injector. Steady off = open circuit. Steady on = shorted to power.
• 📏 Injector resistance, key off: measure injector #1 across the two pins. Compare to another cylinder. All should be similar (typically ~12–16 Ω on this engine).
  • Reading “OL” or much higher = open injector coil.
• 🧵 Harness wiggle test, hot: with engine idling warm, wiggle the injector #1 pigtail and the harness back to the main loom. If idle stumbles or the noid light flickers, you’ve found an intermittent wire/connector.
• 🔍 Connector check: remove injector #1 connector, inspect for spread terminals, corrosion, or green crust. Gently tighten female terminals with a pick. Terminal tension = how snug the pin fits.
• 🧲 Coil/boot/plugs on #1: pull plug #1 and inspect for carbon tracking, oil, or cracked insulator. Check gap at 0.040 in. If you have separate coil/boot, inspect and swap it with another cylinder to see if the misfire moves.
• 🔎 Grounds: clean and retighten engine grounds on the right cylinder head and body ground near battery. A poor ground can create injector driver faults.
• 📈 Fuel pressure under load: if available, tee in a gauge. Spec is ~58 psi key-on/idle. A drop under load mostly causes P0300, but won’t set P0201; still worth confirming.

Circuit specifics for the injector

• ⚡ Power: all injectors share a 12V feed from the ASD relay (dark green/orange wire).
• 🧭 Control: the PCM grounds each injector individually. Cylinder 1 control wire is typically a unique color (varies by production), located at the injector connector opposite the DG/OR power.
• 🧪 Voltage checks, key on:
  • Backprobe injector #1: one pin should have ~12V (DG/OR). If not, ASD feed/relay/wiring issue.
  • With engine cranking/idling, the control wire should be pulsing to ground (seen with a test light to battery positive or a scope). No pulse = PCM driver/wire fault.
• 🔧 Continuity test: key off, battery disconnected. Ohm test from injector #1 control wire to PCM connector pin (refer to your under-hood diagram). You’re looking for near 0 Ω and no short to ground or battery on that wire.

Most likely fixes (in order)

• 🪛 Repair or replace the injector #1 connector/pigtail or harness section due to heat-soak open.
• 🪛 Replace a faulty injector #1 if resistance is out of spec or the swap test moves the fault.
• 🪛 Replace a coil boot/plug for cylinder 1 if you find tracking or gap issues; consider swapping coils/boots between cylinders to confirm.
• 🪛 If all wiring and injector test good but no pulse on #1 only, suspect a PCM driver fault (rare). Verify power/ground to PCM before condemning.

Safety and tips

• ⚠️ Work with the engine cool when unplugging injectors and coils. Fuel rail is under pressure.
• 🧤 Use dielectric grease on connectors when reassembling. It keeps moisture out.
• 🪙 After repairs, clear codes and perform a 10–15 minute mixed drive to confirm no misfire.

Answer those two questions and tell me what you find on the swap/noid/resistance checks. I’ll guide you to the exact fix step-by-step.