Safari Van M V6-262 4.3L VIN Z TBI (1990)
Figure No. 1
Disconnect canister purge line at the canister, see Figure 1.
Apply parking brake.
Place automatic transmission equipped vehicles in PARK and manual transmission equipped vehicles in NELTTRAL.
Start engine and warm up so that coolant temperature is at least 85 degrees C.
Make sure air conditioning system is OFF.
Make sure vehicle is in CLOSED LOOP mode.
Raise engine speed to 2600 rpm and maintain speed.
Monitor BLOCK LEARN (BLM) values and CLOSED LOOP Status at 2600 RPM - wait at least 30 seconds for BLM values to stabilize.
If BLM value at 2600 RPM is less than 115, the timing chain sprockets are misaligned. Realign timing chain sprockets following REPAIR
PROCEDURE section of this bulletin.
If 2600 RPM BLM value is 115 or greater, let engine idle - automatic transmission equipped vehicles in DRIVE and manual transmission
equipped vehicles in NEUTRAL.
Make sure system is still in CLOSED LOOP before continuing, if not, retum to Step #7 and rerun testing sequence.
Monitor BLM values and CLOSED LOOP status at IDLE - wait at least 30 seconds for BLM value to stabilize.
If system switches to OPEN LOOP too soon, rewarm oxygen sensor by shifting transmission to NEUTRAL or PARK and raise engine speed to
1500 RPM until system switches to CLOSED LOOP status.