K 2500 Truck 4WD V6-262 4.3L (1988)
Oxygen Sensor: All Technical Service Bulletins
Exhaust - Catalytic Converter Odor/Rough Idle
GMC NUMBER: 88-T-213
GROUP: 6E - Engine Emission
DATE: September, 1989
CORPORATE NUMBER: 936517
SUBJECT:
ROUGH IDLE AND/OR CONVERTER ODOR
(SERVICE PROCEDURE - NEW PROM)
MODELS:
1988 C1, C2, K1, K2 TRUCKS WITH 4.3L ENGINE (VIN CODE Z)
Some 1988 C/K trucks equipped with 4.3L (VIN Code Z) engines may exhibit an exhaust odor often described as sulfur or rotten egg smell at idle
following sustained highway driving or trailer towing. Additionally, some trucks may exhibit rough or unstable idle quality.
These conditions may generally he addressed by relocating the oxygen sensor from the left hand exhaust manifold to the exhaust takedown (Y-pipe) and
installing the appropriate calibration PROM.
To accomplish this, it will he necessary to obtain the parts listed below:
Qty
Description
Part Number
1
Exhaust Y-pipe
15620225
1
Plug
10017198
2
Seal
15522434
1
Calibration PROM
See Application Table
Parts are currently available form GMSPO.
SERVICE PROCEDURE
1)
Disconnect the battery.
2)
Remove the exhaust Y-pipe and discard.
3)
Install new Y-pipe (P/N 15620225). It may be necessary to replace the exhaust manifold to Y-pipe seals (P/N 15522434) prior to installing the
new Y-pipe.
4)
Remove the oxygen sensor from the left side exhaust manifold and install it in the boss provided in the newly installed Y-pipe using a small
amount of anti-seize compound as described in the Service Manual. Torque the sensor to 30 ft-lb (41 N-M).