Overview
Note. Do not use leaded fuel in a vehicle equipped with a catalytic converter. In a vehicle that is continually misfueled, the lead in the fuel will be deposited in the catalytic converter and completely blanket the catalyst. Lead reacts with platinum to "poison" the catalyst. Continuous use of leaded fuel can destroy the catalyst and render the catalytic converter useless. The addition of lead to the catalytic converter can also solidify the catalyst, causing excessive back pressure in the exhaust system and possibly causing engine damage.
Note. Extremely high temperatures of 1,100°C (2,012°F) or above due to misfiring or an over-rich fuel/air mixture will cause the ceramic substrate to sinter or burn, destroying the catalytic converter. Do not continue to operate the vehicle if the engine is misfiring, there is a power loss or other unusual operating conditions, such as engine overheating and backfiring.
Note. Do not use oil or grease-based lubricants on the isolators. These lubricants may cause deterioration of the rubber. This can lead to separation of the isolator from the exhaust hanger bracket during vehicle operation.
The exhaust system provides an exit for exhaust gases and reduces engine noise by passing exhaust gases through the catalytic converters and a muffler assembly. The catalytic converters also play a major role in reducing air pollutants.
The exhaust system consists of
- a one-piece catalytic converter with exhaust flexible pipe.
- a resonator.
- a muffler and tailpipe assembly with isolators.
The catalytic converter plays a major role in the emission control system. The catalytic converter operates as a gas reactor. Its catalytic function is to speed the heat-producing chemical reaction of components in the exhaust gases in order to reduce air pollutants.
The catalyst material inside the catalytic converter consists of a ceramic substrate.
The catalytic converter is designed to provide a long life. No maintenance is necessary for the catalytic converter.
Sound insulators and shields, attached to the underbody, protect the vehicle from exhaust system heat and should be inspected at regular intervals to make sure they are not dented or out of position. If a sound insulator and shield is damaged or shows evidence of deterioration, install a new insulator and shield. The sound insulators and shields for the muffler, muffler pipe, resonator and catalytic converter pipe are installed separately.
Some exhaust fasteners must be discarded and new ones installed as indicated in the procedures. Also, any damaged or heavily corroded fasteners should be discarded and new ones installed. Some exhaust fasteners are of a prevailing torque design. Use only new fasteners with the same part number as the original. Torque values must be used as specified during reassembly to make sure of correct retention of exhaust components.
Symptom Chart: Symptom Chart - Exhaust System
Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices. For information regarding Ford-specific diagnostic practices
REFER to: DIAGNOSTIC METHODS .
Verify the customer concern and then inspect the components of the exhaust system for obvious signs of damage or other mechanical concerns using the following chart.
| Mechanical |
|---|
| Exhaust pipe pinched or crushed Damaged muffler Broken or damaged exhaust hanger brackets Damaged catalytic converter Loose or damaged heat shields |
VISUAL INSPECTION CHART - MECHANICAL
Verify the exhaust system is installed correctly, with clamps correctly located and tightened to specifications. If the fault is not visually evident, determine the symptom. GO to Symptom Chart below.
| Condition | Possible Sources | Actions |
|---|---|---|
| Vehicle has low or no power - vehicle performance complaint | Exhaust pipe pinched or crushed Damaged catalytic converter Loose obstruction in exhaust | REFER to the ENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS (EXCEPT DIESEL & HYBRID) . |
| Restricted exhaust (possible frozen condensate in muffler) | CHECK drain holes for foreign material. PARK the vehicle inside to thaw. TEST the vehicle for normal operation. If the concern is still present, REFER to the ENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS (EXCEPT DIESEL & HYBRID) . | |
| Burning smell - usually occurs at idle, with possible traces of smoke | Foreign material caught in exhaust system Missing heat shields | INSPECT the exhaust system for foreign material or missing heat shields. REPAIR or INSTALL new components as necessary. |
| Odor - described as a sulfur or rotten egg smell | Catalytic converter Excessive sulfur content in fuel | At times, a slight sulfur smell is normal for catalytic converters. The cause is the sulfur content in the gasoline being used. ADVISE the customer no repair is required. |
| Rich fuel conditions Misfire conditions | REFER to the ENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS (EXCEPT DIESEL & HYBRID) . | |
| Visible rust on surface of exhaust pipes | Catalytic converter/exhaust system | Surface rust is a characteristic of materials used on exhaust systems. Exposure to heat or road salt may result in surface rust. INSPECT for perforations. If there are no perforations, the condition is normal. |
SYMPTOM CHART
Symptom Chart: Symptom Chart - NVH
Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices. For information regarding Ford-specific diagnostic practices
REFER to: DIAGNOSTIC METHODS .
| Condition | Possible Sources | Actions |
|---|---|---|
| Rattle, squeaks or buzz type noise - from the bottom of the vehicle | Loose or damaged heat shield | INSPECT the exhaust system for loose or missing heat shields or foreign material trapped between the heat shields and the exhaust system components. If any heat shields are loose, INSTALL worm gear clamp 7L5Z-5A231-AA and tighten to 7 Nm. If the heat shields are missing or a rattle, noise or buzz condition persists, INSTALL a new heat shield or component as necessary. |
| Loose or damaged exhaust isolators | VERIFY the exhaust isolators are correctly installed. INSPECT the exhaust isolators for wear or damage. INSTALL new isolators as necessary. | |
| Damaged exhaust isolator hanger bracket | INSPECT the exhaust system components for damage or broken hangers. INSTALL new components as necessary. CHECK for loose or damaged exhaust hanger brackets or fasteners. TIGHTEN the bolts to specification or INSTALL new components as necessary. | |
| Loose or damaged catalytic converter or muffler | MOVE the exhaust system to simulate the bouncing action of the vehicle, checking for exhaust-to-body contact while moving the exhaust system. Using a rubber mallet, TAP on the exhaust components to duplicate the noise concern. Lightly TAP on the muffler, then the catalytic converter. DETERMINE if there are loose or broken baffles in the muffler or a loose or broken element in the catalytic converter. REPAIR or INSTALL new components as necessary. | |
| Exhaust grounded to chassis | INSPECT for signs of exhaust components-to-body contact. REPAIR or INSTALL new components as necessary. | |
| Drone or clunk type noise - from the bottom of the vehicle | Loose or damaged exhaust isolators | INSPECT the exhaust isolators for wear or damage. INSTALL new isolators as necessary. |
| Exhaust grounded to chassis | INSPECT for signs of exhaust components-to-body contact. REPAIR or INSTALL new components as necessary. | |
| Whistles, boom, hum or ticking type noise - noise tends to change as the engine warms. The noises are often accompanied by exhaust fumes | Exhaust system leak | INSPECT the entire exhaust system for leaks. CHECK for punctures, loose or damaged clamps/fasteners, gaskets, sensors or broken welds. EXAMINE the chassis for grayish-white or black exhaust soot, which indicates exhaust leakage at that point. To magnify a small leak, have an assistant hold a shop towel over the tail pipe outlet while listening for a leak. REPAIR or INSTALL new components as necessary. |
| Catalytic converter | MOVE the exhaust system to simulate the bouncing action of the vehicle, checking for exhaust-to-body contact while moving the exhaust system. Using a rubber mallet, TAP on the exhaust components to duplicate the noise concern. Lightly TAP on the muffler and the catalytic converter. DETERMINE if there are loose or broken baffles in the muffler, or a loose or broken element in the catalytic converter. REPAIR or INSTALL new components as necessary. | |
| Exhaust muffler/resonator drain hole enlarged due to corrosion | CONFIRM the drain holes are the noise source. INSTALL new components as necessary. | |
| Hissing or rushing noise - high frequency sound and the vehicle performance is unaffected | Exhaust system Exhaust flow through pipes | CHECK the exhaust system for leaks. Using a rubber mallet, TAP on the exhaust components to duplicate the noise concern. Lightly TAP on the muffler and the catalytic converter. Determine if there are loose or broken baffles in the muffler, or a loose or broken element in the catalytic converter. REPAIR or INSTALL new components as necessary. |
| Pinging noise - occurs when exhaust system is hot, engine turned off | Catalytic converter/exhaust system | Cool down pinging is a result of the exhaust system expanding and contracting during heating and cooling. This is a normal condition. |
| Vibration - occurs at idle and at low speeds. Also accompanied by a clunk or buzz type noise | Loose or damaged exhaust isolator | INSPECT the exhaust isolators for wear or damage. INSTALL new isolators as necessary. |
| Loose or damaged exhaust isolator hanger brackets | INSPECT the exhaust isolator hanger brackets for wear or damage. INSTALL or REPAIR as necessary. | |
| Exhaust system grounded to chassis | REPAIR or INSTALL new components as necessary. | |
| Engine drumming noise - normally accompanied by vibration | Damaged or misaligned exhaust system | INSPECT the exhaust system for loose or damaged fasteners or isolators. REPAIR or INSTALL new components as necessary. |
| Sputter type noise - noise worse when cold, lessens or disappears when the vehicle is at operating temperature | Damaged or worn exhaust system | INSPECT the exhaust system for leaks or damage. REPAIR as necessary. |
| Thumping noise - from the bottom of the vehicle, worse during acceleration | Misaligned exhaust system | CHECK the exhaust system to chassis clearance. CHECK the exhaust system isolators for damage. REPAIR as necessary. |
| Engine vibration - is felt with increases and decreases in engine rpm | Strain on exhaust system isolators | REPAIR or INSTALL new components as necessary. |
| Drumming noise - occurs inside the vehicle during idle or high idle, hot or cold. Very low-frequency drumming is very rpm dependent | Refer to the Pinpoint Test | GO to Pinpoint Test A |
SYMPTOM CHART
Pinpoint Test(s)
Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices.
REFER to: DIAGNOSTIC METHODS .
Possible Sources
- Exhaust system vibration excites the body resonances inducing interior noise
- Misaligned exhaust system
- Broken, loose or damaged exhaust hanger brackets
- Exhaust system grounded to chassis
- Loose or damaged exhaust isolator
- Loose or damaged heat shields
PINPOINT TEST A: DRUMMING NOISE
Pinpoint Test A
Catalytic Converter
| Cable Ties |
SPECIAL TOOL(S) / GENERAL EQUIPMENT
Removal
Note. Removal steps in this procedure may contain installation details.
Scheme 11
Scheme 12
Scheme 13
Scheme 14
Scheme 15
Scheme 16
Scheme 17
Scheme 18
Scheme 19
- Torque : 10 Nm
- Refer to: «JACKING AND LIFTING - OVERVIEW»(/ford/focus-st/iii-2012-2015/remont/hoistjack/#jacking-lifting-except-electric) .
- Torque : 70 Nm
- General Equipment : Cable Ties
- Tighten the nuts in this sequence.
- Torque : 25 Nm Torque : 25 Nm
- Tighten the nuts in this sequence. Torque : 48 Nm Torque : 25 Nm
- Torque : 20 Nm
- NOTE: During installation, tighten the nut finger tight at this stage.
Scheme 20
Installation
- To install, reverse the removal procedure.
Note. It is necessary to cut the production exhaust system to enable the service sections to be fitted. Before cutting any part of the exhaust system, check that the position of the cut is correct in comparison to the service sections to be installed.
Note. Service section parts will use service section clamps for assembly.
Scheme 21
Scheme 22
- Refer to: «HEALTH AND SAFETY PRECAUTIONS»(/ford/focus-st/iii-2012-2015/remont/oem-general-information/#service-information-introduction-except-electric) .
- Refer to: «JACKING AND LIFTING - OVERVIEW»(/ford/focus-st/iii-2012-2015/remont/hoistjack/#jacking-lifting-except-electric) .
- NOTE: Do not forcibly bend or twist the exhaust flexible pipe. Failure to follow these instructions may cause damage to the flexible pipe.
- During installation, install 2 new catalytic converter manifold-to-muffler and tailpipe nuts and tighten in 2 stages in the sequence shown. Torque : 48 Nm
- To install, reverse the removal procedure.