CO-Check & Adjustments; Enrichment Systems Information
CO-CHECK AND ADJUSTMENTSConnect the lambda sensor.
Warm up the engine to normal operating temperature. Check that ignition timing and idle speed are within specification. Adjust when necessary.
Check the "dwell" reading on the MONOTESTER. The reading should not be stable. With the correct CO setting, the reading should fluctuate around the following values:
B28F (CI) 43 degrees (41-44)
B23FT, B230FT, B230F (LH) 20-70 degrees
ADJUSTMENT
B28F (CI): A high reading indicates a lean mixture and the CO adjustment screw should be turned clockwise. A low reading indicates a rich mixture and the CO adjustment screw should be turned counter-clockwise.
B23FT, B230FT, B230F (LH): A high reading indicates a rich mixture and the CO adjustment screw should be turned counter-clockwise. A low reading indicates a lean mixture and the CO adjustment screw should be turned clockwise.
The adjustment range on LH-Engines is 15 turns on the CO adjustment screw. The range where the pointer fluctuates on LH engines is equivalent to one turn on the CO adjustment screw.
NOTE: The emission regulations in the U.S. and Canada require access to CO-adjustment be sealed. After adjustment, the CO-adjustment must be resealed.
ENRICHMENT SYSTEMS, B28F (CI)
The CI-system for B28F is equipped with inter-related enrichment systems:
^ Cold start enrichment system
^ Acceleration enrichment system
^ Full load enrichment system
These systems can also be checked with the use of the Monotester.
COLD START ENRICHMENT SYSTEM
This system is only engaged, when the coolant temperature is below +15 degrees C (+60 degrees F). This system can also be checked at temperatures above +15 degrees C (+60 degrees F) by grounding terminal 7 at Lambda control unit.
The reading when activated should be 52 - 56 degrees.
ACCELERATION ENRICHMENT SYSTEM
This function is only engaged at coolant temperatures below 53 degrees C (+127 degrees F).
This system should be checked with a cold engine, but can also be checked with the engine at normal operating temperatures.
Procedure
Connect a vacuum pump to the pressure differential switch and evacuate switch.
Release vacuum. When vacuum is released, the switch closes. The dwell meter reading should change to 70 degrees or above for a short period and then decrease.
NO READING OR INCORRECT READING
^ Connect a jumper wire between the pins in the connector, as illustrated.
If meter now reads 70 degrees or above, wiring and control unit is OK.
^ Check vacuum hoses (replace if applicable).
^ Check thermo valve.
^ Check differential switch.
FULL LOAD ENRICHMENT SYSTEM
FUNCTION CHECK
On the B28F engines, this system can be tested by "closing" the microswitch at the throttle pulley. The reading should be 54 +/- 2 degrees.
NO READING OR INCORRECT READING
^ Check wiring/connector continuity.
^ Check microswitch.
^ Check control unit.