Emission monitors are internal self-tests which the engine control computer (ECU) performs in order to verify specific emissions systems, such as the EGR system, EVAP system, oxygen sensors and Catalyst, are functioning properly. If any one monitor is incomplete (except for the EVAP) your Toyota 4Runner will be unable to pass the smog test. In order to make the monitors ready for the smog check you'll need to drive your 4Runner through what is referred to as a Drive Cycle.
Usually driving 200-300 miles over the course of a few days and in both city and highway traffic conditions is enough to get the drive cycle complete. Due to individual vehicle owner driving patterns however, sometimes the criteria required to get a particular monitor to initiate and/or become ready is not met. In such instances, it is required that a specific drive cycle pattern which is designed for the Toyota 4Runner 4.7 L, be followed.
The drive cycle is a bit complex. Please perform is at your own risk. If you feel you may be unable to perform the drive cycle below safely, please seek assistance from a reputable smog check repair station or Toyota dealership.
How to Perform Toyota 4Runner Drive Cycle (2RZ-FE / 3RZ-FE / 5VZ-FE)
Begin by: (Make sure you have between 1/4 and 3/4 fuel in the gas tank. The EVAP test will not run while your SUV has a full tank of gas or the gas tank is near empty). Ensure there are no pending or active trouble codes and that the check engine light is not on.
Also note, the secondary air injection monitor only runs after a cold soak procedure... best done by leaving your 4Runner parked overnight. Getting the air injection monitor to run after the engine has warmed up is not possible. If you've been trying to get the monitor ready after having already warmed up the SUV you'll need to wait until the difference between IAT (Intake Air) and ECT (Coolant Temp) is less than 13F (7C). The cold soak procedure is as follow:
1a. Start the engine and allow ECT (Coolant Temp) to reach 176F (80C) or greater. (This can be done by letting the engine idle or by driving the vehicle.)
1b. Let the vehicle cold soak for 8 hours or until the difference between IAT (Intake Air) and ECT (Coolant Temp) is less than 13F (7C).
Start the Drive Cycle Here
A. Start the engine and allow it to idle for 10 minutes or more.
B. Drive the vehicle at 43-56 mph or more for 3 to 5 minutes. Be sure to maintain engine speed between 900 and 3,200 rpm.
C. Stop the vehicle and allow the engine to idle for 3 to 5 minutes.
D. Repeat steps B and C once.
E. Drive the vehicle at 40 mph to 55 mph for 3 minutes.
F. Drive the vehicle 35 mph to 45 mph for 7 minutes.
G. Stop the vehicle and turn off the engine. Release the pressure in the fuel tank by removing and then reinstalling the fuel tank cap.
H. Start the engine and as soon as safely possible begin driving at approximately 45 mph for 5 minutes.
I. Drive the vehicle at approximately 25 mph for 15 minutes, and include a minimum of two stops for approximately 30 seconds each.
J. Stop the vehicle and allow the engine to idle for 2 minutes.
K. Drive the vehicle at 25 mph or more for at least 50 seconds. Make sure your engine speed is above 900 rpm.
L. Stop the vehicle and allow the engine to idle for 40 seconds or more.
M. Perform steps “K” and “L” ten times.
If readiness status of all monitors do not switch to “complete,” ensure preconditions are met, turn the ignition switch OFF, then repeat steps “A” through “M.” Completing the Toyota 4Runner drive cycle above should set the emission monitors required to pass the smog check.