Maxima 4 (1994-1999)

Catalytic Converter — General Information, Checking Condition and Replacement (Nissan Maxima A32)

Table of contents: General information ↓ Examination ↓ Replacement of components ↓

Note. To avoid violating the warranty obligations that apply to components of exhaust gas reduction systems, check and maintain the catalytic converter in the workshop of a car service station.

General information

A catalytic converter is a component of exhaust gas toxicity reduction systems, is included in the exhaust system and serves to reduce the emission of toxic components into the atmosphere. The vehicles discussed in this Manual use two types of catalytic converters. A conventional oxidation converter reduces the content of hydrocarbons and carbon monoxide in the exhaust gases. A three-function catalytic converter additionally reduces the emission of nitrogen oxides (NOX).

Examination

1. Diagnostic equipment for checking the catalytic converter is expensive and extremely difficult to operate. If you suspect a converter failure, take the car to a service station for inspection.

2. Every time the vehicle is raised above the ground for any reason, inspect the converter for signs of mechanical damage, leaks and corrosion. Check the condition of the welds and the tightness of the flange bolts that secure the device to the exhaust system sections. A defective catalytic converter must be replaced.

3. Despite the reliability of the converter design, there is a fairly high probability of its blockage. The simplest way to check the patency of the converter is to check using a vacuum gauge:

a) Connect a vacuum gauge to the vacuum source of the intake manifold (see section General engine overhaul Chapters Engine);
b) Warm up the engine to normal operating temperature, move the selector lever to position "P" (models with AT), or put the transmission in neutral (models with manual transmission) and set the parking brake;
c) Read the vacuum gauge readings with the engine idling;
d) Open the throttle valve, increasing the engine speed to 2000 rpm;
e) Quickly release the valve and read the vacuum gauge;
f) Repeat the described test three more times, each time recording the result;
g) If the result of the fourth measurement is more than 2.5 mm Hg lower than the reading taken at idle speed, then there is a possibility that the converter or the exhaust pipe is blocked.