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Failed Smog Test
 

Nissan Frontier Emission Monitors Not Ready After 500+ Miles of Driving

My 2006 Nissan Frontier failed the California smog test due to a not ready condition. The smog station said the liquid fuel leak monitor (EVAP) was not ready. I did replace the fuel pump last month but I have driven the truck over 500 miles since then and the monitor is still not ready.

Answer:  

Having driven your Nissan Frontier for over 500 miles should have been enough to get the emission monitors ready for the smog test. Sometimes however the driving pattern required to complete the emission monitors are not met during normal city/highway driving, and following the required and specific Nissan Frontier drive cycle/pattern is needed.

Below we indicate the drive cycle required for Nissan Frontier trucks, step-by-step. Following the drive cycle below (at least twice) should make the required emission monitors READY/COMPLETE.

Please take extra caution while performing drive cycle on public roadways. If you think you will be unable to follow the Nissan Frontier drive cycle below safely, seek the assistance of a smog check repair station or Nissan dealership. They will be able to complete the drive cycle in-house and on a dynamometer.

In regards to the EVAP Emission Monitor specifically, it is very important to ensure the drive cycle is initiated while the fuel tank is between 15% and 85% full before and during the drive cycle. The EVAP monitor can not complete with low fuel level or a full tank of gas. Part of the EVAP monitor self-test requires that the fuel tank pressure sensor measure the vacuum/pressure of the fuel tank. When the tank is full or empty, the EVAP monitor can not accurately detect vapor leaks and thus the EVAP monitor can not become ready or complete.

Nissan Frontier Drive Cycle for OBDII Monitors

Pre-Conditioning Requirements:

Ensure the MIL (malfunction indicator lamp) is not on.

Gas tank fuel level must be between 15% and 85% at all times.

Drive cycle must start while engine is cold. Best performed in the morning and after being parked overnight. The actual requirement is that the engine be between 68 and 86 degrees F prior to the start of the drive cycle.

Drive Trace:

A. Start your truck and idle engine until coolant temperature reaches 160F (until normal operating temperature is reached).

B. Using a timer, idle the engine for an additional 1 1/2 minutes.

C. Begin driving. Accelerate smoothly to 56 mph with the transmission in (D) and overdrive ON, then release gas pedal and coast for 10 seconds.

D. Accelerate to 56 mph and maintain speed for at least 10 minutes. Use smooth and quick acceleration and maintain speed as constant as possible.

E. Stop and idle your Nissan Frontier for 10 seconds.

F. Accelerate to 25 mph in 10 seconds and hold gas pedal steady for 20 seconds. Use smooth and quick acceleration and maintain speed as constant as possible.

G. Repeat steps E and F eight (8) times. Decelerate (coast down) to 15 mph and then drive for 13 minutes at speeds between 15mph and 35mph.

H. Accelerate to 53-56 mph and maintain speed for at least 6 minutes. In this step it is more important to maintain accelerator pedal position than speed. Therefore you are allowed 3 mph fluctuation in speed, but must try and keep the gas pedal steady.

- End of Drive Cycle -

If all emissions systems are functioning properly, completing the drive cycle above will set the emission monitors (also known as readiness flags) required to pass the smog check. We recommend performing the drive cycle at least twice before visiting a smog check station.



posted by SmogTips Support
 


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