Emissions - Conversion Specification Changes
84volvo02Subject: Product
B23F M.Y. 1984 CARS
Specification Group
Changes 25
Date: No.
May, 1984 37
THIS SERVICE BULLETIN APPLIES TO THE U.S. AND CANADIAN MARKETS
The following specification revisions have been introduced to improve emission conversion; especially during warm-up and at low engine load.
INSULATED FRONT EXHAUST PIPE
- Reduces exhaust temperature loss. Increased exhaust temperature at the catalytic converter inlet improves emission conversion efficiency.
NEW CATALYTIC CONVERTER
- The shell for the catalytic converter is made in two pieces and welded together (clam shell design). Improves durability.
NEW PRE-HEATING SHIELD
- New design, mounted on the exhaust manifold. Repositioned due to the insulated front pipe.
HEATED LAMBDA SENSOR
- Positive temperature coefficient (PTC) - heated lambda sensor.
Improved function and durability. Replacement at 30,000 miles is no longer a maintenance requirement. Mileage counter and lambda sensor indicator lamp deleted.
The above specification was introduced in production in march (week 411) with effect from the following engine .
PART NUMBERS
- manual 499944 (old P/N 499846)
- Automatic 499945 (old P/N 499847)
The lambda sensor requires a temperature of approximately 350~C (662~F) before it starts to function. A (PTC) resistor inside the sensor is used to heat the sensor. It also increases the temperature at idle and low engine load, which results in a more stable sensor output.
Resistance of the PTC-resistor:
Cold sensor, 20~C (68~F). . . . . . 3 ohm
Warm sensor, above 350~C (662~F). 13 ohm
WIRING DIAGRAM
The PTC-resistor in the lambda sensor (6) is connected to the electrical system by two wires. One to ground and one to fuel pump relay terminal 87 (voltage supply), as illustrated.