Engine ignition system V6 volume of 3.5 liters installed on a crossover Nissan Murano generation Z51, requires regular maintenance to maintain dynamics and efficiency. Many owners are faced with the need to replace system elements due to increased mileage, which inevitably leads to worse sparking and unstable engine operation.
The procedure for replacing spark plugs on this model has its own design features related to the tight layout of the engine compartment and access to the rear row of cylinders. Ignoring maintenance regulations can lead to failure of expensive ignition coils or even damage to the spark plugs themselves during dismantling.
In this article we will analyze in detail all stages of work, from selecting suitable components to the final check of the engine. You'll learn what tools you'll need, how to avoid common mistakes, and why it's important to follow the specified tightening torques.
Maintenance schedule and signs of wear
Manufacturer Nissan recommends scheduled replacement of spark plugs every 100,000 kilometers when using original iridium elements. However, real operating conditions, such as frequent city trips, traffic jams and the use of low-quality fuel, can reduce this interval to 60,000 - 80,000 kilometers.
The need for replacement can be determined by indirect signs that manifest themselves in changes in the behavior of the car. If you notice increased fuel consumption, floating idle speed or difficulty starting the engine, you should check the condition of the spark plugs immediately.
Symptoms indicating problems in the ignition system:
- 🔥 Unstable engine operation at idle, noticeable vibration
- ⛽ Significant increase in fuel consumption with the same driving style
- ⚡ Loss of power, especially noticeable during sudden acceleration or going uphill
- 🚨 Indicator lights up
Check Enginewith error codes for misfires
It is important to note that failure of one cylinder can cause the catalytic converter to overheat, resulting in very expensive repairs. Ignoring misfire errors on a V6 engine can lead to failure of the catalyst and lambda probes within several thousand kilometers.
⚠️ Attention: Do not delay replacing the spark plugs if the car starts to misfire. Long-term operation on three cylinders can lead to burnout of piston rings and burnout of valves due to unburned fuel.
Selection of components: original or analogues
For engine VQ35DE or upgraded versions installed on Murano Z51, it is critical to use plugs with the correct thermal characteristics and gap. The most common and reliable option is the original iridium spark plugs Nissan with article number 22401-ED00A (or similar, depending on the year of manufacture).
If you're considering alternative options, check out brands like NGK or Denso. These companies are often suppliers of original components for the conveyor, so their products fully meet the requirements of engineers Nissan.
Key parameters when choosing:
- 💎 Iridium sputtering - ensures long service life and stable spark
- 📏 Electrode gap - must strictly correspond to the factory 1.1 mm
- 🔧 Threaded part - the thread length should not exceed the standard one so as not to touch the valves
Avoid buying cheap nickel-plated analogues, as they are designed for a shorter life and may not provide the required sparking under load. Saving on spark plugs often results in the need for more frequent replacement and risk for the ignition coils.
- Nissan (Original)
- NGK
- Denso
- I don’t know/Haven’t changed it yet
Tools and workplace preparation
To do the job well, you will need a specialized set of tools, since a standard garage kit may not be suitable due to close access to the rear spark plugs. Be sure to have a spark plug wrench with an extension and a universal joint.
List of required equipment:
- 🛠️ 16 mm spark plug wrench (preferably with a magnetic holder or rubber band)
- 🔗 Cardan extension (flexible shaft) for access to the rear spark plugs
- 💨 Compressed air in a can or compressor for cleaning wells
- 🧽 Rags and graphite thread lubricant (do not use copper paste)
Before starting work, the car must be driven into a pit or overpass to provide easy access to the bottom and engine protection. If this is not possible, it will be enough to raise the front part on jacks, but working in tight spaces will be more difficult.
☑️ Preparing to replace spark plugs
Step-by-step instructions for dismantling and installation
First you need to remove the plastic decorative engine cover. To do this, carefully unclip the latches and lift it up, disconnecting the crankcase ventilation hose. After removing the casing, you will see the ignition coils arranged in two rows.
The process of dismantling the coils is as follows:
- ⚡ Disconnect the electrical connector by pressing the lock on the side
- 🔩 Unscrew the coil mounting bolt (usually 10 mm or 8 mm)
- 🧲 Gently pull the coil up to remove it from the well
Now you can move on to unscrewing the spark plugs. Use a spark plug wrench with an extension to reach the rear row of cylinders. Turn the key counterclockwise using moderate force. If the spark plug is tightly tightened, do not jerk so as not to strip the threads in the cylinder head.
Before installing new spark plugs be sure to blow out the spark plug wells with compressed air so that fine dust and dirt do not get inside the cylinder during dismantling. This is a critical step that is often ignored by inexperienced technicians, resulting in cylinder scuffing.
Install new spark plugs manually until they stop, so as not to distort the threads. Only then can you use the tightening wrench. Tightening torque for engine spark plugs VQ35 is strictly 13 Nm (about 1.3 kgf m).
⚠️ Attention: If you do not have a torque wrench, tighten the spark plug after manual installation by 1/4 - 1/2 turn, but no more. Over-tightening may cause the ceramic insulator to deform and spark to ground.
What to do if the spark plug won't come out?
If the candle sticks, do not use excessive force immediately. Treat the joint with a penetrating lubricant (such as WD-40 or Liquid Wrench) and let it sit for 10-15 minutes. Try tightening the spark plug slightly and then unscrewing it. If the thread breaks, the cylinder head will need to be repaired or a repair insert installed.
Coil check and diagnostics
When replacing spark plugs, be sure to inspect the condition of the ignition coils. On Murano Z51 they often fail along with the spark plugs, since old spark plugs create an increased load on the spark system. Check them for cracks, signs of breakdown or carbon deposits.
Symptoms of a faulty coil:
- 💥 Traces of black soot or burning on the rubber tip
- 🌫️ Microcracks on the plastic body of the reel
- 📉 Errors for a specific cylinder in the diagnostic scanner
If you see even the slightest sign of breakdown, it is highly recommended to replace the coil. The cost of a new coil is not comparable to the cost of a new catalyst, which can be damaged by unburnt fuel when operating at skips.
When removing the coils, try not to pull on the wire, but rather on the plastic housing of the connector. Sudden jerks can damage the contacts inside the connector or break the wire inside the insulation.
Comparative table of candle characteristics
For clarity, we present a comparison of the main characteristics of spark plugs suitable for the 3.5L V6 engine. This table will help you choose the best option based on your priorities and budget.
| Candlestick pattern | Electrode type | Resource (km) | Tightening torque (Nm) |
|---|---|---|---|
| Nissan 22401-ED00A | Iridium | 100 000+ | 13 |
| NGK ILZKR7B-11 | Iridium | 90 000 | 13 |
| Denso PK20PR-P11 | Platinum | 80 000 | 13 |
| Bosch FR7NPP332S | Platinum | 70 000 | 13 |
The use of iridium spark plugs ensures stable engine operation throughout the entire regulatory period, reducing the risk of misfire and increased exhaust toxicity.
Final assembly and check
After installing all the spark plugs and coils, you need to return the decorative engine casing and connect the connectors. Make sure that the latches click into place and that the coil bolts are tightened securely.
Before starting the engine, check that there are no unnecessary tools or rags left in the engine compartment. Connect the battery and start the engine. It should work smoothly, without vibrations or extraneous noise.
If after replacement you hear a clicking sound or vibration, immediately turn off the engine and check the tightness of the spark plugs. Incorrect installation may result in gases leaking from the combustion chamber, which will destroy the spark plug sealing ring.
Frequently Asked Questions
Is it possible to change spark plugs without removing the intake manifold?
Yes, on the VQ35DE (Z51) engine you can change the spark plugs without removing the intake manifold. Access to the front spark plugs is free, to the rear spark plugs - through an extension and cardan. However, for convenience and better access to the rear spark plugs, some craftsmen recommend removing the air filter pipe and decorative plastic.
Do I need to change ignition coils when replacing spark plugs?
If the coils are in perfect condition, there is no need to change them. But if the mileage exceeds 100,000 km and they have never been changed, preventive replacement of the rear coils (the most loaded) is recommended, since old spark plugs could “kill” them.
What happens if you do not observe the tightening torque of the spark plugs?
An undercompressed spark plug will cause overheating and gas leakage, which can destroy the spark plug and the cylinder head. An overtightened spark plug can cause deformation of the ceramic insulator, which will lead to a short circuit and failure of the ignition coil.
How to understand that candles are on Nissan Murano is it time to change?
Main symptoms: difficult starting, engine tripping, increased fuel consumption and misfire errors (P0300-P0306). It is also worth focusing on the mileage - 100,000 km for iridium spark plugs.