Spark plugs for Nissan Sunny FB15: how to choose and replace correctly

Nissan Sunny FB15 (1990–1994) - the legendary Japanese sedan, which is still in use on the roads of the CIS. His engine GA15DE (1.5 l, 90–102 hp) is sensitive to the quality of spark plugs: incorrect selection or wear of parts leads to tripping, increased fuel consumption and even detonation. In this article we will look at which candles are suitable for FB15 according to original catalogues, how to check, change them and what mistakes owners make during maintenance.

Motor Feature GA15DE — high compression ratio (9.5:1) and distributed injection system. This places stringent demands on heat number candles: too “hot” ones will provoke glow ignition, and “cold” ones will quickly become covered with soot. The manufacturer recommends adhering to the standard NGK BCP6ES or its analogues, but there are also more modern options on the market with iridium electrodes.

Original spark plugs and their analogues for Nissan Sunny FB15

In the manual for Sunny FB15 There are two main recommendations:

• 🔧 NGK BCP6ES (article 22401-4M000) - standard nickel spark plugs with a copper core. Resource: 20–30 thousand km.
• 🔥 Denso W16EP-U (article K16PR-U11) - an alternative from another Japanese manufacturer, interchangeable with NGK.

However, these models are outdated and are often counterfeited today. More reliable analogues with improved characteristics:

• ⚡ NGK BCP6E (without the letter S) - a simplified version without a resistor, suitable for older ignition systems.
• 💎 Denso IK16 — iridium spark plugs with a service life of up to 60 thousand km, but require checking the gap (optimally 0.8–0.9 mm).
• 🔄 Bosch WR7DC - a German analogue, often found in stores, but the quality varies depending on the batch.

Important: spark plugs with platinum or multi-electrode tips (for example, NGK G-Power) are not recommended for GA15DE - they can cause misfires due to the design of the coil.

How to check the condition of spark plugs on FB15

Diagnostics of spark plugs is the first step in case of unstable engine operation. On Sunny FB15 They are easy to remove, but before doing so, it is worth assessing the external signs of a malfunction:

• ⚠️ Triple at idle or under load.
• 🔥 Increased fuel consumption (more than 9 l/100 km in the city).
• 🚗 Dips during acceleration, especially at the “bottoms”.
• 🔊 Popping sounds in the exhaust system - a sign of misfire.

For visual inspection:

1. Remove the high voltage wires (hold the cap, not the wire!).
2. Unscrew the spark plugs with a spark plug wrench 21 mm.
3. Rate the color of the electrodes:
   • 🟤 Light brown - the norm.
   • ⚫ Black soot - rich mixture or oil in the combustion chamber.
   • ⚪ White coating - lean mixture or overheating.
   • 🟠 Red plaque - low-quality fuel with additives.

What to do if the candle is “wet”?

A wet plug (with gasoline or oil) indicates problems with the ignition system or compression. If it is gasoline, check the coil and high-voltage wires. If there is oil, wear on the valve stem seals or rings. In both cases, diagnosis is required.

Critical point: on the FB15, the sealing ring of the spark plug well (part number 11085-4M000) often wears out. If it is not replaced, moisture or dirt will enter the well, which will lead to a breakdown of the high-voltage wire.

Step-by-step replacement of spark plugs on Nissan Sunny FB15

Replacing spark plugs with GA15DE takes 30–40 minutes. You will need:

• 🔧 Candle key on 21 mm with extension cord.
• 🧲 Magnet or tweezers for removing candles.
• 🧴 Dielectric grease (optional, for caps).
• 📏 Feeler gauge for checking the gap (if you use non-original spark plugs).

Algorithm of actions:

1. Disconnect the negative terminal of the battery (required!).
2. Remove the decorative engine cover (4 plastic clips).
3. Disconnect the high-voltage wires from the spark plugs, remembering their location (or marking them with a marker).
4. Unscrew the spark plugs counterclockwise. If they do not give in, do not apply force, but treat the threads with WD-40 and wait 10 minutes.
5. Clean the wells from dirt (you can use compressed air).
6. Install new spark plugs by screwing them in manually until it stops, then tighten with the wrench 20–25 Nm.
7. Connect the wires in reverse order.

⚠️ Attention: Never use spark plugs with damaged threads or cracks on the insulator - this will lead to breakdown and failure of the ignition coil. On the FB15, the coil is expensive (from 8 thousand rubles), and its replacement requires disassembling half of the engine compartment.

Typical mistakes when replacing spark plugs on FB15

Even experienced owners Sunny make mistakes that are costly later. Let's look at the top 5 misses:

1. Re-upholstery of candles. Thread in aluminum block head GA15DE breaks easily. Maximum effort - 25 Nm (or 3/4 turn after “by hand”).
2. Using copper candles. They quickly oxidize and “stick” to the thread. Only nickel plated spark plugs are suitable for FB15.
3. Ignoring O-rings. They need to be changed every 2 spark plug changes (or at the first sign of an oil leak).
4. Confusion with high-voltage wires. On GA15DE The order of the cylinders is 1-3-4-2 (when viewed from the radiator). If you mix it up, the engine will stall.
5. Saving on clearance. Even if the package says “the gap is set,” check it with a feeler gauge. Optimal for FB15 0.8–0.9 mm.

Another common problem is buying fake candles. Up to 40% of counterfeit products on the market NGK And Denso. How to distinguish the original:

• 🏷️ The packaging must have a hologram and a barcode, which can be checked on the manufacturer’s website.
• 🔍 On original candles NGK The logo is laser engraved rather than painted.
• 📦 The kit includes a protective cap for the thread (counterfeits often do not have it).

Comparison of spark plugs for Nissan Sunny FB15: characteristics table

To make your choice easier, we have collected the key parameters of popular models:

Model	Manufacturer	Heat number	Gap (mm)	Electrode material	Resource (thousand km)	Notes
BCP6ES	NGK	6	0.8–0.9	Nickel	20–30	Original, resistor
W16EP-U	Denso	16	0.8	Nickel	25–35	Analogue NGK BCP6ES
IK16	Denso	16	0.8	Iridium	50–60	Requires clearance check
WR7DC	Bosch	7	0.9	Nickel	20–25	Often counterfeited
FR7DCU	Bosch	7	0.9	Platinum	40–50	Not recommended for GA15DE

Please note: heat number 6 (NGK) corresponds to 16 (Denso) - these are different notation systems. Don't be confused!

When to change spark plugs: regulations and signs of wear

The manufacturer recommends replacement every 30 thousand km, but in practice the period depends on the operating conditions:

• 🏙️ City mode (frequent traffic jams, short trips) - every 20–25 thousand km.
• 🛣️ Route (uniform loads) - up to 40 thousand km.
• ⛽ Gas equipment — every 15–20 thousand km (gas destroys electrodes faster).

Signs that it's time to change spark plugs regardless of mileage:

• 🔥 The engine starts only after 2-3 attempts.
• 📉 Loss of power (the car “does not pull” on climbs).
• 💨 Smoke from the exhaust pipe (black or gray).
• 🔊 Extraneous sounds in the area of the ignition coil (crackling, hissing).

⚠️ Attention: On FB15 with a mileage of more than 150 thousand km, wear of spark plugs can mask other problems: malfunction of the lambda probe, air leaks or camshaft wear. If symptoms remain after replacing the spark plugs, a comprehensive diagnosis is required.

Frequently asked questions about spark plugs for Nissan Sunny FB15

Is it possible to install iridium spark plugs on GA15DE?

Yes, but with reservations. Iridium spark plugs (eg Denso IK16) are suitable for FB15 if:

• The engine is in good condition (no oil burn, normal compression).
• You check the gap (optimally 0.8 mm).
• Use high-quality fuel (not lower than AI-95).

On a worn engine, iridium spark plugs can cause misfires due to a weak spark.

What happens if you don't change spark plugs on time?

The consequences range from unpleasant to critical:

• 🔥 Detonation - explosive combustion of fuel, which destroys pistons and rings.
• 🛢️ Increased oil consumption — due to incomplete combustion of fuel, the oil scraper rings become coked.
• 🔌 Ignition coil breakdown - if the spark plug “breaks through”, the high voltage damages the coil winding.
• 🚗 Engine failure - in advanced cases, major repairs are required.

What should be the spark plug gap for FB15?

Optimal clearance - 0.8–0.9 mm. If less, the spark will be weak; if more, misfires will occur. Check the gap flat probe, not with a coin or a screwdriver!

For gas equipment, the gap can be reduced to 0.7 mm, since gas requires a more “powerful” spark.

Can old candles be cleaned and reused?

Theoretically yes, but in practice it is inappropriate. Even after cleaning:

• The electrodes become thinner, which impairs sparking.
• Carbon deposits may remain in the pores of the insulator, which will lead to breakdown.
• The resistor (if there is one) loses its properties.

The exception is a temporary measure in the field (for example, if the candle is filled with gasoline). To clean, use sandblaster or ultrasound, but not sandpaper!

Why does the engine run worse after replacing spark plugs?

There are several reasons:

1. Incorrect clearance (too large or small).
2. The high-voltage wires are mixed up (check the connection order).
3. Defective candles (especially if you bought cheap analogues).
4. Problems with the ignition coil or distributor (on the FB15 the Hall sensor often fails).

First check the gap and order of the wires. If it doesn’t help, return the old spark plugs and compare engine performance.