Owners Nissan Murano Z50 (2003–2007) are often faced with the need to know the exact numbering of engine cylinders - be it replacing spark plugs or diagnosing misfires (P0300-P0306) or cylinder head repair. Errors in determining the order of the cylinders can lead to serious consequences: from incorrect installation of high-voltage wires to damage to the ignition coils. In this article we will analyze official numbering scheme for engines VQ35DE (3.5 l) and VQ25DE (2.5 l), as well as nuances that are not indicated in the manuals.

Feature Murano Z50 — transverse engine arrangement, which confuses many car owners when searching for the 1st cylinder. Unlike classical diagrams (where the numbering comes from the crankshaft pulley), here you need to focus on timing side and flywheel position. We will look in detail at how to find the first cylinder without dismantling parts, using visual marks and diagnostic equipment.

Official cylinder numbering scheme for VQ35DE/VQ25DE

Series engines VQ, installed on Murano Z50, have standard for Nissan cylinder numbering, but adjusted for transverse arrangement. Basic rules:

  • 🔢 1st cylinder always on the side passenger side (on the right, if you look in the direction of travel).
  • 🔄 Numbering is in progress from right to left per row: 1–3–5 (front row), 2–4–6 (back row).
  • 🔧 Cylinder markings are applied to the cylinder head cover (can be hidden under the intake manifold).
  • ⚡ In the control unit (ECU) the cylinders are numbered similarly, which is important for diagnosing type errors P0301 (missing in cylinder 1).

For clarity, here is a layout diagram:

Row Cylinder 1 Cylinder 2 Cylinder 3
Front (cabin side) 1 3 5
Rear (radiator side) 2 4 6

Important! On Murano Z50 with VQ25DE (2.5 l) the numbering order is identical, but the 6th cylinder is missing. Instead, in place of the 5th cylinder is located balance shaft, which is often confusing when replacing spark plugs.

📊 What engine is installed in your Murano Z50?
  • VQ35DE (3.5 l)
  • VQ25DE (2.5 l)
  • Other
  • I don't know

How to visually identify the 1st cylinder without disassembling

If you do not have a diagram under the hood, you can find the 1st cylinder using the following criteria:

  1. Through high voltage wires: the shortest wire goes to the 1st cylinder (located closer to the passenger compartment).
  2. By ignition coils: on VQ35DE the coil of the 1st cylinder is located right (if you look at the engine from the radiator side) and is marked CYL 1 on the body.
  3. By timing belt: 1st cylinder is on the side tension roller (closer to the generator).

For an accurate check, use diagnostic scanner (For example, Launch X431 or ELM327): in parameters Misfire Counts cylinders are displayed in official order. If the scanner shows gaps in CYL 4, this means the 4th cylinder in our diagram (back row, second from left).

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When replacing spark plugs, always take photographs of the location of the high-voltage wires before dismantling. This will help avoid confusion when reassembling, especially if the wires are not labeled.

Common mistakes when working with cylinders

Incorrect cylinder numbering leads to serious problems. Here are typical mistakes and their consequences:

  • ⚡ Mixed up high voltage wires: leads to P0300 (random omissions) and vibrations at idle. The engine may stall, and the scanner will show errors in all cylinders.
  • 🔧 Incorrect replacement of spark plugs: if you put spark plugs with the wrong heat rating into “foreign” cylinders, this will cause detonation and damage to the pistons.
  • 🛠️ Errors during cylinder head repair: incorrect installation of hydraulic compensators or valves on the cylinders leads to P0011/P0021 (valve timing errors).
⚠️ Attention! On Murano Z50 with VQ35DE ignition coils not interchangeable in rows! The front row coils (1–3–5) have a different part number than the rear row (2–4–6). Installing a “foreign” coil will lead to misfires.

To avoid mistakes, always check with electrical circuit (found in the service documentation Nissan under the code EWD). For example, for 2005 Murano Z50 the scheme is relevant EWD-M51.

Cylinder numbering for error diagnosis

When reading type errors P030X (where X - cylinder number) it is important to understand that ECU uses the same numbering as on the engine. For example:

  • P0301 - gaps in 1st cylinder (front row, far right).
  • P0304 - gaps in 4th cylinder (back row, second from left).
  • P0306 - gaps in 6th cylinder (only for VQ35DE).

If the scanner shows P0300 (random omissions), check:

Correct connection of high-voltage wires|

Condition of spark plugs (gap, carbon deposits, cracks)|

Ignition coil resistance (normal: 0.5–1.0 Ohm)|

Compression in cylinders (dispersion no more than 1 bar) |

Crankshaft position sensor wiring integrity (CKP)

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On Murano Z50 common reason P0300 — wear of contacts in coil connectors. Oxidation or poor contact results in an intermittent signal that ECU perceives as misfires in all cylinders.

What should I do if the scanner shows errors in all cylinders?

This may indicate:

1. Malfunction ignition module (on VQ35DE it is located under the coils).

2. Problems with ECU power supply (check fuse IGN in the block under the hood).

3. Damage wiring harness from the coils to the ECU (often rubs against the intake manifold).

In this case, a check with an oscilloscope or replacement of the module assembly is required (part number: 22448-AL50A for Murano Z50 2003–2005).

Numbering features on models with AWD

On all-wheel drive versions Murano Z50 (All-Mode 4WD) the order of the cylinders is not different, but there are nuances:

  • 🔗 Additional crankshaft position sensor (CKP2) is installed to synchronize with the transfer case. Its malfunction can simulate misfires in the 2nd and 5th cylinders.
  • 🛠️ Narrow access to the rear row of cylinders due to the rear wheel drive cardan. To replace the spark plugs you will need to remove intake manifold or use flexible extension for the key.

On AWD versions the problem is also more common with overheating of the 3rd cylinder (front row, middle). This is due to the peculiarities of the cooling system when all-wheel drive is activated. Signs of overheating:

  • 🔥 Darkening of the candle (white or gray soot).
  • 📉 Compression drop (below 10 bar).
  • 🚨 Error P0303 during long off-road driving.
⚠️ Attention! If on Murano Z50 AWD After replacing the spark plugs, misfires appeared in the 3rd cylinder, check thermostat (article 21200-4M000). Its jamming in the closed position leads to local overheating of the middle cylinder.

Practical application: replacing spark plugs and coils

Let's look at step-by-step instructions for replacing spark plugs, taking into account the numbering of the cylinders. You will need:

  • 🔧 Candle key with extension cord (length at least 20 cm).
  • 🧲 Magnetic grip for extracting candles from deep wells.
  • 🔌 Dielectric grease for coil contacts.

Procedure:

  1. Disable negative battery terminal (required to avoid damage ECU).
  2. Remove decorative engine cover (attached with 4 latches).
  3. Disconnect the coil connectors starting at 1st cylinder (mark them with a marker!).
  4. Unscrew the bolts securing the coils (tightening torque for reassembly: 10 Nm).
  5. Remove the spools and blow out the wells with compressed air (dirt getting into the cylinder = scuffing!).
  6. Unscrew the spark plugs starting from 6th cylinder (this is more convenient due to limited space).

Critical! On Murano Z50 The rear row spark plugs (2-4-6) have a different tightening torque - 20 Nm instead of 25 Nm for the front row. Exceeding the torque leads to damage to the threads in the aluminum cylinder head.

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When replacing ignition coils, always use original parts (part number: 22448-4M000 for rows 1–3–5, 22448-4M001 for 2–4–6). Analogs (for example, Denso or NGK) may not match the length of the spark gap, which will cause gaps.

FAQ: Frequently asked questions about cylinder numbering

❓ Why are the coil numbers out of order on my Murano Z50?

On some versions (e.g. for the US market), the coils are labeled by production order rather than by cylinder. Focus on connector position: for the coil of the 1st cylinder the connector is directed towards the passenger compartment, for the 6th cylinder - towards the radiator.

❓ Is it possible to swap coils between rows?

No! The front and rear row coils have different spark tip length. Installing a coil from the back row to the front will result in P0300 and vibrations.

❓ How to check compression if there is no access to the 4th cylinder?

Use flexible extension for compression gauge or remove intake manifold. An alternative is diagnostics by Relative Compression scanner (for example, in Launch X431 there is this test).

❓ Why did code P0302 appear after replacing the spark plugs?

Most likely, the high-voltage wires between the 2nd and 4th cylinders are mixed up. Check also insulation integrity wires - on Murano Z50 they often rub against the air conditioner bracket.

❓ Where can I find the official numbering scheme for my VIN?

Download Service Manual for your VIN on the website Nissan TechInfo (section Engine Mechanical → Cylinder Numbering). For Murano Z50 manuals with code are relevant M51 (2003–2004) or M52 (2005–2007).