P0307 on 2010-2013 GMC Savana: Cylinder 7 Misfire Causes and Fixes

What's Unique About the 2010-2013 Gmc SAVANA

The GMC Savana vans from this era are equipped with GM's Vortec V8 engines, many of which feature Active Fuel Management (AFM), also known as Displacement on Demand (DOD). While generally reliable, the tight engine bay of a van can lead to higher under-hood temperatures, accelerating wear on ignition components. More critically, the AFM system is a known weak point. The specialized lifters for cylinders 1, 4, 6, and 7 can fail, becoming stuck or collapsing. This is a very common cause for a persistent P0307 code that isn't resolved by replacing ignition parts. A specific Technical Service Bulletin (TSB #PIP4819A) also points to loose spark plug wires as a known, simpler cause for misfires on this platform.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Engine shaking or vibrating, especially at idle
• Rough running and stumbling during acceleration
• Flashing or solid Check Engine Light
• Noticeable loss of engine power
• Difficulty starting the engine
• Increased fuel consumption
• Ticking or tapping noise from the engine, especially on a cold start

Most Likely Causes

1. Loose or Damaged Spark Plug Wire 🔴 High Probability → Shop Spark Plug A manufacturer TSB (#PIP4819A) was issued specifically for this issue on 2010 models, indicating a known problem with loose spark plug wires causing misfires.
   How to confirm: Visually inspect the spark plug wire for cylinder 7. Ensure it is securely connected at both the ignition coil and the spark plug. Check for any signs of damage, arcing (white marks), or corrosion.
   Typical fix: Reseat the wire securely or replace the spark plug wire set if damaged.
   Est. part cost: $40-$80 for a full set
2. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil
   How to confirm: Swap the ignition coil from cylinder 7 with a coil from another cylinder (e.g., cylinder 1). Clear the codes and drive the vehicle. If the misfire code changes to P0301, the coil is faulty.
   Typical fix: Replace the failed ignition coil.
   Est. part cost: $30-$75
3. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug
   How to confirm: Remove the spark plug from cylinder 7 and inspect its condition. Look for a worn electrode, heavy carbon buildup, oil fouling, or cracks in the porcelain insulator.
   Typical fix: Replace the spark plug. It is recommended to replace all spark plugs at the same time for even performance.
   Est. part cost: $5-$20 per plug
4. Clogged or Failed Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Listen for a consistent clicking sound from the injector with the engine running. Use a 'noid light' to verify the electrical pulse from the PCM. For a more definitive test, swap the injector with another cylinder to see if the misfire follows. One forum user noted that debris can collect at the end of the fuel rail, clogging the #7 injector specifically.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $50-$120

Rare But Worth Checking

• Low Cylinder Compression: Internal engine issues like a burnt valve, worn piston rings, or a leaking head gasket can cause a persistent misfire. A compression test is required to diagnose this. A healthy cylinder should have compression over 140 PSI and be within 15% of the other cylinders.
• Intake Manifold Gasket Leak: → Shop Engine Intake Manifold A vacuum leak near the intake runner for cylinder 7 can lean out the air-fuel mixture and cause a misfire. This can sometimes be detected with a smoke test or by carefully spraying starter fluid near the gasket and listening for a change in engine RPM.
• Broken Exhaust Manifold Bolt: Vortec engines are known for the rearmost exhaust manifold bolts breaking off, creating an exhaust leak. While this more commonly causes lean codes, a significant leak near the cylinder could potentially affect O2 sensor readings and contribute to misfire detection.
• Carbon Buildup on Valves: Per GM TSB 16-NA-383, significant carbon buildup on intake or exhaust valves can cause them to stick, leading to misfires. This is more common on engines with over 5,000 miles and can be caused by fuel quality issues. Diagnosis often requires a borescope to visually inspect the valves.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and confirm P0307 is present. 🎬 Watch: A quick overview of P0307 causes and fixes. Note any other codes, especially P0300.
2. Locate cylinder 7. On GM V8s, the cylinders on the driver's side are 1, 3, 5, 7, from front to back. Cylinder 7 is the rearmost cylinder on the driver's side.
3. As per TSB #PIP4819A, first inspect the spark plug wire for cylinder 7. Ensure it is firmly attached at both the coil and the spark plug.
4. Swap the ignition coil from cylinder 7 with an adjacent coil (e.g., cylinder 5). Clear the codes, run the engine, and see if the misfire code moves to P0305. If it does, the coil is bad.
5. If the misfire remains on cylinder 7, remove and inspect the spark plug. Replace it if it appears worn, fouled, or damaged.
6. If ignition components are confirmed good, test the fuel injector. Listen for its clicking operation or use a noid light to check for an electrical signal.
7. Listen for a distinct ticking or tapping noise from the engine. If present, suspect a failed AFM lifter.
8. If a lifter failure is suspected, remove the driver's side valve cover. Start the engine briefly and watch the rocker arms for cylinder 7. If a rocker arm is not moving, the lifter has collapsed and must be replaced.
🎬 Watch: Step-by-step guide to replacing lifters and removing the head.
9. If the above steps do not isolate the issue, perform a cylinder compression test to check for internal engine mechanical issues like bad rings or valves.
10. Check for vacuum leaks around the intake manifold, particularly near the runner for cylinder 7.

Parts You'll Likely Need

• Ignition Coil (OEM #12674754) — Ignition coils are a very common failure point for misfires. Swapping them is a key diagnostic step.
  Trusted brands: ACDelco, Delphi, NGK
  OEM price range: $50-$80
  Aftermarket price range: $30-$60
• Spark Plug (OEM #41-110) — As a routine maintenance item, spark plugs wear out and are a primary cause of misfires. Use the specified Iridium plug for longevity.
  Trusted brands: ACDelco, NGK
  OEM price range: $8-$15
  Aftermarket price range: $5-$12
• Spark Plug Wire Set (OEM #9748RR) — A TSB specifically calls out loose wires as a cause for this code on this vehicle. Wires can also degrade over time, causing weak spark.
  Trusted brands: ACDelco, NGK
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• AFM Valve Lifter (OEM #12645725) — A failed AFM lifter is a significant cause of P0307 on this platform. This part is required if diagnosis points to a collapsed lifter. It's sold in a package of 4.
  Trusted brands: ACDelco, Sealed Power
  OEM price range: $120-$160 (for set of 4)
  Aftermarket price range: $80-$120 (for set of 4)
• Valve Lifter Oil Manifold (VLOM) (OEM #12660737) — This manifold controls oil flow to the AFM lifters. It is often replaced as part of an AFM lifter repair job, as it contains solenoids that can fail.
  Trusted brands: ACDelco, Dorman
  OEM price range: $150-$250
  Aftermarket price range: $100-$180

Related Codes That Often Appear With This One

• P0300 — This code for 'Random/Multiple Cylinder Misfire' often appears alongside a specific cylinder code like P0307 if the underlying issue (like a failing AFM system or fuel delivery problem) is starting to affect other cylinders or is intermittent across the engine.

Technical Service Bulletins (TSBs) & Recalls

• PIP4819A: Addresses engine misfires (P0300-P0308) resulting from loose spark plug wires.
• 15-06-01-002 (series A through N): Details diagnosis and repair for engine misfire/tick noise caused by a mechanically collapsed or stuck Active Fuel Management (AFM) lifter.
• PIP5162: Discusses diagnostic codes related to camshaft position which can be related to oiling issues that also affect AFM lifters.
• 19-NA-218 (replaces PIP5606E): Addresses ticking noise from the engine on cold start, which is a primary symptom of a failing lifter.
• 16-NA-383: Details engine misfire or rough idle caused by heavy carbon buildup on intake and/or exhaust valves.

Platform-Specific Known Issues

• A Technical Service Bulletin (TSB #PIP4819A) was issued for 2010 models, noting that loose spark plug wires could cause misfire codes, including P0307. The recommended fix is to inspect and replace any loose wires.
• A series of TSBs (most notably #15-06-01-002) address a widespread issue with Active Fuel Management (AFM) lifters failing. Cylinder 7 is one of the four AFM cylinders, making it highly susceptible to this failure. Symptoms include a P0300 or P0307 code and a distinct engine ticking noise. The repair is extensive, requiring cylinder head removal.

Mechanic-Grade Diagnostic Values

• Fuel Pressure (Key On, Engine Off) — expected: 50 to 65 PSI. Failure: Pressure below 50 PSI can indicate a weak fuel pump or clogged filter.
• Fuel Pressure (Engine Idling) — expected: 52 to 62 PSI. Failure: Pressure significantly lower than the KOEO reading or below 50 PSI suggests a fuel delivery issue.
• Ignition Coil Primary Resistance — expected: 0.4 to 2.0 ohms. Failure: A reading outside this range (often open loop/infinite or zero) indicates a faulty primary winding.
• Ignition Coil Secondary Resistance — expected: 6,000 to 15,000 ohms (6k-15k Ω). Failure: A reading significantly outside this range points to a failure in the secondary coil winding.
• Fuel Injector Resistance (5.3L V8) — expected: 11.7 to 13.5 ohms. Failure: A reading significantly higher or lower than the others, or out of spec, indicates a failing injector coil. A small variation like 0.3 ohms is generally acceptable.
• AFM VLOM Solenoid Resistance — expected: 11 to 18 ohms. Failure: A reading outside this range when testing the pins on the VLOM connector indicates a faulty solenoid.

Hidden / Shadow Codes Worth Checking

• Mode $06 Misfire Counters: Most professional scan tools, and specifically the GM Tech2/GDS2, can access live misfire counters for each cylinder. This data shows misfire events that are occurring but have not yet reached the threshold to set a P0307 trouble code. This is invaluable for confirming a misfire exists when the Check Engine Light is not on or for seeing the immediate effect of diagnostic actions. (see via GM Tech2, GDS2, or high-end professional scan tool with GM-specific software under the 'Misfire Data' or 'Mode $06' menu.)

Scan Tool Commands That Help

• GDS2 / Tech2: Cylinder Power Balance Test — This test automatically disables each cylinder one by one and measures the corresponding drop in engine RPM. A smaller RPM drop for cylinder 7 confirms it is contributing less power than the others, helping to isolate the fault.
• GDS2 / Tech2: AFM/DOD Cylinder Deactivation Test — Allows the technician to command the AFM solenoids in the VLOM on and off to test their electrical function and observe the engine's response. This can help diagnose a faulty VLOM if AFM-related issues are suspected.
• GDS2 / Tech2: Fuel Injector Balance Test — This function fires each injector for a set duration and measures the drop in fuel rail pressure. A smaller pressure drop when cylinder 7's injector is fired indicates it is clogged or flowing less fuel than the others.
• GDS2 / Tech2: Crankshaft Variation Learn (CASE Relearn) — If the crankshaft position sensor has been replaced, the PCM has been reprogrammed, or if false misfires are suspected due to road vibration, performing a CASE relearn can improve the accuracy of misfire detection.

Real Owner Repair Stories

• YouTube channel 'Got a Misfire' (Chevrolet Silverado with 5.3L V8 (similar LS-based engine with AFM)) — Persistent P0307 misfire code.
  ❌ Tried (didn't work) Not specified, but implied that basic ignition/fuel checks did not resolve the issue.
  ✅ What actually fixed it The cause was a collapsed Active Fuel Management (AFM) lifter on cylinder 7. The lifter had physically come apart. The diagnosis was confirmed by removing the valve cover and starting the engine, which showed the rocker arm for one of the valves on cylinder 7 was not moving.
• YouTube channel 'MotorCity Mechanic' (2014-2020 GM Truck with 5.3L L83 V8 (newer generation but same AFM principle)) — P0300, P0301, P0307, P050D codes. Engine misfire.
  ❌ Tried (didn't work) Initial diagnosis pointed to valve cover and rocker arms.
  ✅ What actually fixed it A collapsed AFM lifter on cylinder 7 was the root cause. The repair involved removing the cylinder head to access and replace all AFM lifters on the driver's side bank. The video highlights the collapsed lifter and the process of replacement.

OEM Part Supersession History

• 12645725 → 12740071 — This is the AFM/DOD Valve Lifter. Part numbers are often updated to reflect design improvements or manufacturing changes aimed at increasing durability and preventing the common collapse/sticking failure.
• 12660737 → 19433052 — This is the Valve Lifter Oil Manifold (VLOM) which controls oil flow to the AFM lifters. The part was likely updated to improve the reliability of the internal solenoids and prevent oil pressure issues that contribute to lifter failure.