Exhaust system <em>Nissan Sunny FB15</em>: device, diagnostics and do-it-yourself repair

Exhaust system Nissan Sunny FB15 (1990–1995) is one of the most vulnerable components of a car, especially after 20+ years of operation. Corrosion, burnt-out corrugations and mufflers, as well as problems with the catalyst become a headache for owners. But do not rush to change the entire system: in 80% of cases, local repairs or replacement of individual elements are sufficient.

In this article we will analyze FB15 exhaust system design, typical malfunctions (with photos and signs), and we will also give step-by-step repair instructions — from replacing gaskets to welding the muffler. We will pay special attention unique feature of FB15: two exhaust system options (for markets with hard and soft eco-standards), which are often confused when purchasing spare parts.

Exhaust system design Nissan Sunny FB15: circuit and components

Exhaust system Sunny FB15 consists of 5 main elements connected by flanges and clamps. The design depends on the year of manufacture and the market:

• 🔥 Exhaust manifold — cast iron (less often steel), attached to the cylinder head with 4 bolts. On models for Japan and Europe it was often installed catalytic converter right in the collector.
• 🌀 Reception pipe (downpipe) — connects the collector to the resonator. For US and Canadian versions, this is located here. second catalyst (EPA standard).
• 🔊 Front resonator (pre-muffler) — dampens high-frequency vibrations. Often burns out due to condensation.
• 🚗 Corrugation (vibration compensator) — present only on versions with automatic transmission. On the “mechanics” it is not present, which simplifies the design.
• 🔇 Main muffler — the largest element, mounted on rubber hangers. Inside there are perforated pipes and sound-absorbing material.

Feature of FB15 - two types of systems:

1. For strict eco-standards (Japan, Europe, USA): two catalysts (in the manifold + in the exhaust pipe), oxygen sensor (λ probe) after the first catalyst.
2. For soft standards (Middle East, Africa, CIS): one catalyst or its complete absence, no second oxygen sensor.

When purchasing spare parts, be sure to check VIN code or check the catalog numbers. For example, the muffler from the Japanese version (18010-4M000) is not suitable for the model without a catalyst (18010-4M010).

Typical malfunctions: signs and causes

Average exhaust system life FB15 - 150–200 thousand km, but in Russian conditions it is reduced to 100 thousand km due to:

• ☠️ Corrosion — welds, flanges and hanger mounting points rust.
• 🔥 Burnout — the thin metal of the resonator and muffler is destroyed by high temperatures.
• 💥 Mechanical damage - impacts on uneven surfaces, breakage of suspensions.
• 🚨 Clogged catalyst - leads to loss of power and error P0420 (low catalyst efficiency).

How to recognize the problem:

Symptom	Probable Cause	What to do
Loud roar when accelerating	Burnt out resonator or muffler	Visual inspection, replacement or welding
Rattling under the bottom	The muffler hanger has come off or the bracket has cracked	Replace suspension rubber bands (18085-4M000)
Black smoke from the exhaust	Rich mixture (faulty injectors, mass air flow sensor) or clogged catalyst	Engine diagnostics, back pressure check
Error P0420 on the dashboard	The catalyst or oxygen sensor has failed	Checking with a scanner, replacing the catalyst or replacing the λ-probe

⚠️ Attention: If, after replacing the catalyst with a flame arrester, the Check Engine, will require ECU firmware or installation decoys (emulator of the second oxygen sensor). On FB15 with GA16DE this can be solved programmatically, but SR20DE - hardware only.

Exhaust system diagnostics: step-by-step instructions

Start the check with a visual inspection on a lift or inspection pit. You will need:

• 🔦 Flashlight (preferably LED).
• 🔧 14 mm wrench for checking fasteners.
• 📏 Ruler or caliper for measuring backlash.
• 🎤 Stethoscope (or long screwdriver) to listen for leaks.

Check the integrity of the welds on the manifold and exhaust pipe|

Inspect the corrugation (if any) for cracks and tears|

Listen to the system for leaks (characteristic hissing)|

Check the play of the muffler hangers (tolerance - no more than 5 mm)|

Measure the back pressure in the system (the norm is up to 0.3 kg/cm² at idle) -->

Pay special attention to:

1. Connection of the manifold to the cylinder head - the gasket often leaks here (11056-4M000). Symptom: black traces of carbon deposits around the flange.
2. Corrugation (on automatic transmission) - if it is torn, vibrations will be transmitted to the body. Replacement only with the original (18065-4M000) or a high-quality analogue Walker.
3. Catalyst - tap it with the wooden handle of a hammer. A dull sound means the cells are melting.

To check back pressure:

1. Disconnect the first λ probe (before the catalyst).
2. Insert a pressure gauge with an adapter into the hole.
3. Start the engine. Pressure higher 0.5 kg/cm² at 3000 rpm - a sign of a clogged catalyst.

How to check a catalyst without a pressure gauge?

Remove the front λ probe and start the engine. If the exhaust sound becomes noticeably louder and the speed rises to 1500–2000 (without pressing the gas), the catalyst is clogged. This method only works on FB15 with a working ignition system!

Repair vs replacement: which is more profitable for Sunny FB15?

The cost of a new exhaust system for FB15 is from 25 to 60 thousand rubles (depending on the configuration). But in most cases you can get by partial renovation:

• 🔧 Manifold gasket — replacement will cost 500–800 rubles. (on your own) or 1.5–2 thousand rubles. in the service.
• 🛠️ Burnt out resonator — welding a new insert costs 2–3 thousand rubles, replacing with a new one costs 5–7 thousand rubles.
• 🔥 Corrugation — replacement only complete with exhaust pipe (from 4 thousand rubles), since it is not dismountable.
• 🚫 Catalyst — removal and installation of a flame arrester will cost 3–5 thousand rubles. (plus ECU firmware).

When replacement is inevitable:

• Corrosion destroyed more than 30% of the pipe area.
• Cracks in the manifold or exhaust pipe (welding here is unreliable due to high temperatures).
• Failure of flange connections (for example, the mounting ear broke off).

⚠️ Attention: On FB15 with engine SR20DE It is strictly not recommended to remove the catalyst without reflashing the ECU. This leads to over-enrichment of the mixture and rapid failure of the second λ-probe (after 1–2 thousand km).

Selection of spare parts: original vs analogues

Original parts from Nissan for FB15 have not been produced for a long time, but there are high-quality analogues:

Detail	Original number	Recommended analogue	Note
Rear muffler	18010-4M000	Walker 20936 or Bosal 234-103	Suitable for versions with catalytic converter
Front resonator	18020-4M000	Magnetti Marelli 120754010001	Metal thickness 1.5 mm (versus 1.2 mm for cheap analogues)
Corrugation (vibration compensator)	18065-4M000	HJS 11.01.00.0410	Only for versions with automatic transmission
Manifold gasket	11056-4M000	Elring 443.530 or Reinz 71-40133-00	Changes every time the manifold is removed

When choosing analogues, pay attention to:

• 📏 Metal thickness — optimally 1.5–2 mm. Cheap mufflers (0.8–1 mm) burn out within 10–15 thousand km.
• 🔩 Fastenings - FB15 uses flanges for M8 bolts, not M10, as on newer models.
• 🔊 Sound — a high-quality muffler should not be “thumpy” at idle. Normal: uniform noise without wheezing.

Where to buy:

• 🛒 For original parts: Nissan Classic Parts (Europe), Ammco (Japan).
• 🌍 For analogues: Exist.ru, Autodoc, Emex. Beware of counterfeit brands Walker And Bosal — check for holograms.
• 🔧 For welding: buy pipes from stainless steel AISI 409 (marking on the surface).

Step-by-step replacement of muffler and resonator

To work you will need:

• 🔧 Set of heads (10, 12, 14 mm).
• 🔨 A grinder or a hacksaw for metal (if the rusty bolts cannot be unscrewed).
• 🔥 Gas burner (for heating stuck nuts).
• 🧲 Magnetic holder (so as not to lose the nuts at the bottom).
• 🛠️ New pendants (18085-4M000) and gaskets.

Procedure:

1. Jack up the rear of the car and secure it on supports.
2. Remove the heat shield (4 x 10mm bolts) under the bottom.
3. Spray all flange joints with WD-40 and let sit for 15-20 minutes.
4. Unscrew the clamp between the resonator and the muffler (12 mm wrench).
5. Remove the rubber hangers while supporting the muffler (it's heavy!).
6. Install the new muffler in reverse order. Important: do not tighten the clamps all the way - leave a gap of 1-2 mm for thermal expansion.

Tips:

• 🔥 If the bolts are stuck, heat them with a burner and unscrew them while it’s hot.
• 🔧 When installing a new resonator, lubricate the flanges copper grease - this will make future replacement easier.
• 🔊 After replacement, check the system for leaks: start the engine and walk your hand along the seams (it should pull air inward, not blow outward).

⚠️ Attention: On FB15 with SR20DE after replacing the exhaust system it may be necessary throttle adaptation. To do this:

1. Reset the battery terminal for 10 minutes.
2. Start the engine and let it idle for 5 minutes.
3. Rev up to 3000 rpm 2-3 times.

If the speed fluctuates, reset the adaptations via Consult-II or similar scanner.

Removing the catalyst: pros, cons and consequences

Many FB15 owners decide to remove the catalyst due to its high cost (15–25 thousand rubles) or clogged conditions. But this solution has serious consequences:

• ✅ Pros:
• 💨 The passage of exhaust gases improves (an increase of 5–7 hp).
• 💰 Savings on replacement (a flame arrester costs 1.5–2 thousand rubles).
• 🔧 The design is simplified (fewer elements for rust).
• ❌ Cons:
• 🚨 Lights up Check Engine (requires snag or firmware).
• 🌍 Exhaust toxicity increases (you will not pass eco-standards when tested).
• 🔊 The noise increases (the flame arrester does not dampen the sound as effectively).

How to remove a catalyst right:

1. Cut off the catalyst body with a grinder (leaving the flanges).
2. Remove the internal honeycomb and install a flame arrester (eg MG-Race or Fox).
3. Weld the body using argon welding (regular welding will quickly burn out).
4. Install λ-probe blende (mechanical or electronic) or reflash the ECU.

For engines GA16DE And SR20DE different deceptions will do:

• 🔧 Mechanical — welded into the pipe in front of the second λ-probe. It costs 500–800 rubles, but requires precise installation (the distance to the sensor is 15–20 cm).
• 💻 Electronic — emulates the signal of a working catalyst. Price: 1.5–2.5 thousand rubles. (for example, Catalyst Emulator Universal).

What happens if you simply knock out the catalyst without installing a flame arrester?

Without a flame arrester, the flow of gases will hit directly into the resonator, which will lead to its rapid burnout (after 5-10 thousand km). In addition, a sharp metallic sound will appear during acceleration, and a hum will be heard in the cabin. On SR20DE this may also cause an error P0300 (misfire) due to back pressure failure.

FAQ: Frequently asked questions about the exhaust system Nissan Sunny FB15

Is it possible to drive with a burnt out muffler?

Short-term - yes, but it is fraught with:

• Exhaust gases entering the cabin (risk of CO poisoning).
• Overheating of the trunk floor (if the rear part of the muffler is burnt out).
• A fine for exceeding noise standards (from 500 rubles).

If the hole is small (up to 5 mm), it can be temporarily sealed heat-resistant sealant (For example, Abro ES-332) or fiberglass bandage.

Which muffler is better - stainless steel or aluminized steel?

Comparison:

Parameter	Stainless steel	Aluminized steel
Service life	8–10 years	3–5 years
Price	30–50% more expensive	Budget option
Noise	Slightly quieter (better dampens vibrations)	Chattering may occur over time

For FB15 the optimal option is: stainless steel for the resonator + aluminized steel for the muffler. This will balance price and durability.

Why did a whistle appear after replacing the exhaust system?

Reasons:

1. Leaky connections — check the clamps and gaskets. It often whistles through a leaky exhaust pipe flange.
2. Bad welding - if the muffler was welded semi-automatically, microcracks could remain.
3. Catalyst clogged — the whistle appears due to gas turbulence in front of the obstacle.

Solution: Treat the seams sealant for exhaust systems (For example, Permatex 81180) and check the back pressure.

Which λ probe is suitable for FB15 with catalyst removed?

Suitable for deception:

• Bosch 0 258 006 537 — universal sensor for mechanical blende.
• NGK 91890 — original analogue, works with electronic emulators.

Important: the sensor must be broadband (4 wires), not two-pin. After installing the cheat, reset the errors via ELM327 or similar adapter.

Can I install an exhaust system from another Nissan model?

Yes, but with reservations:

• Nissan Pulsar N14 (1991–1995) — full compatibility in fastenings and diameters.
• Nissan Almera N15 (1995–2000) — only the rear muffler is suitable, but the suspensions will need modification.
• Nissan Primera P10 — not suitable, despite the similar engine (SR20DE), since the pipe configuration is different.

Check before purchasing pipe length and flange location. For example, at Pulsar N14 The exhaust pipe is 5 cm shorter, so it may not fit with the FB15 manifold.