Emissions Test Issue

mikez71 said:

Looking online, that code seems to mainly indicate a bad vent valve?
I believe I have seen that mentioned somewhere here as well..

Click to expand...

The "vapor canister purge valve" was swapped out for a new oem replacement and the code reoccurred three or so weeks later.
GM called it vapor canister purge valve # 12597567.

Funny thing is that they call the part in the rear under the truck a vapor canister vent valve (very similar name).
Some vendors seem to call that "solenoid".
Were you referring to the part in the rear under the truck?

EddieC said:

Any idea how many miles or amount of time is needed to get the sensors active?

Click to expand...

I am being told at least 50 miles to reset.

EddieC said:

The "vapor canister purge valve" was swapped out for a new oem replacement and the code reoccurred three or so weeks later.
GM called it vapor canister purge valve # 12597567.

Funny thing is that they call the part in the rear under the truck a vapor canister vent valve (very similar name).
Some vendors seem to call that "solenoid".
Were you referring to the part in the rear under the truck?

Click to expand...

Yep, exactly that..

I guess I would double check the wiring and hose connections..
Then maybe replace the other parts in the system. (canister, hoses if bad?)

Might check your old vent valve and make sure you can't blow through it? idk

A procedure from Range Technologies, the ones that make that AFM disabler...

Cut and pasted below.
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The GM EVAP monitor procedure is a known trouble spot for all GM vehicles (regardless of any tunes or the AFM Disabler being installed). It can take several cold soak drive cycles AND a tank of gas to set at times just due to all the complicated parameters that have to be set in order for the monitor to transition from NOT READY to READY
Below is the GM procedure:
Inspection/Maintenance (I/M) Complete System Set Procedure
Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provide an overview of each diagnostic category.

Description
The purpose of the Inspection/Maintenance (I/M) complete system set procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics and complete the drive cycles for those particular diagnostics. When all I/M monitored diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform the Inspection/Maintenance (I/M) Complete System Set Procedure if any I/M System Status indicators are set to NO.
I/M Data List
To determine if the I/M readiness diagnostic tests can be run this ignition cycle, use a scan tool to observe the I/M monitor enabled parameters in the I/M Data List.
Conditions for Meeting a Cold Start

• The ignition voltage between 11-18 volts.
• The barometric pressure (BARO) is more than 75 kPa.
• The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
• The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
• The difference between the IAT and the ECT is less than or equal to 6°C (10.8°F)
• The ambient air temperature is between 4-30°C (39-86°F).
• Fuel level is between 15-85 percent
• Without RPO LMG--The fuel alcohol content is less than 15 percent.
• With RPO LMG--The fuel alcohol content is less than 87 percent.

Circuit/System Verification
Review the Inspection/Maintenance (I/M) System Status indicators with a scan tool. All I/M System Status indicators should report YES.

Inspection/Maintenance (I/M) System Set Procedure
Important: Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, do NOT turn the engine OFF for the remaining portion of the set procedure.

1. Ensure that the vehicle meets the conditions for a cold start listed above.
   ⇒ If the evaporative emission (EVAP) I/M System Status indicator displays NO, perform the EVAP Service bay test if available.
   ⇒ If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES.
   ⇒ If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
2. Set the vehicle parking brake and ensure the vehicle is in park for automatic transmission or neutral for manual transmission.
3. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
4. Start and idle the engine for at least 2 minutes and until 65°C (149°F) is achieved.
5. Run the engine for 6.5 minutes within the following conditions:
   1. MAF parameter between 4-30 g/s
   2. Engine speed steady between 1000-3000 RPM
6. Return the engine to idle for 1 minute.
7. Apply and hold brake pedal, and shift to Drive for automatic, or apply clutch pedal for manual and operate the vehicle within the following conditions for 2 minutes:
   1. Depress the accelerator pedal until TP Sensor angle is more than 2 percent.
   2. MAF signal between 15-30 g/s
   3. RPM steady between 1200-2000 RPM
   4. Important
   : Do NOT touch the accelerator pedal during the idle period. A change in TP Sensor angle or an increase in engine speed may invalidate this portion of the test.
8. Release the accelerator pedal and shift the vehicle to Park for automatic, or Neutral and release clutch pedal for manual, and allow the engine to idle for 2 minutes.
9. Quickly depress the accelerator pedal until TP Sensor Angle is more than 8 percent and return to idle, repeat 3 times.
10. Allow engine to idle for at least 2 minutes.
11. Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
12. Continue to drive the vehicle for at least 5.5 miles between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
13. Release the accelerator pedal for at least 2 seconds. This will allow the vehicle to enter decel fuel cut-off.
14. Depress the accelerator pedal until the TP Sensor angle is increased 3-20 percent and maintain a safe speed for 1 minute.
15. Safely stop the vehicle, with the engine in drive for automatic or in neutral with the clutch pedal depressed and parking brake applied for manual, idle for 2 minutes.
16. Shift to Park for automatic and apply the parking brake, or neutral and release clutch pedal for manual.
    
    Important: Do NOT disturb the vehicle or turn ON the ignition until told to do so. Disturbing the vehicle may invalidate this portion of the test.
17. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 45 minutes.
18. Observe the Inspection/Maintenance (I/M) System Status with a scan tool. All of the I/M System Status indicators should display YES.
    ⇒ If the EVAP I/M System Status indicator displays NO turn OFF the ignition for 17 hours, ensure that the vehicle meets the conditions for a cold start, and repeat steps 12-18 six more times, or until the EVAP I/M System Status indicator transitions to YES. If the indicator continues to display NO, refer to the Inspection/Maintenance (I/M) System DTC Table to identify the DTCs that did not run. Follow the Conditions for Running the DTC in order to set the EVAP I/M System Status indicator
    ⇒ If any of the I/M System Status indicators display NO, refer to the Inspection/Maintenance (I/M) System DTC Table for the indicator which did not display YES. The I/M System DTC Table identifies the DTCs associated with each I/M System Status Indicator. Follow the Conditions for Running the DTC in order to set the associated status indicator.

generic​

Ken Mosher

EddieC said:

Back on this.
Going back, a P0449 error code occurred and was reset just before the the emission test at the start of this thread so I assume that is why the EVAP "not ready" reports came at the emissions code.

As a shot at the code, a new oem vapor canister purge valve (atop engine) was installed.
Since then, no code, and we've been driving, probably 300 miles or so in the past three weeks since the test and planning on checking the "readiness" and get retested today (neither happened) because the P0449 code returned today.

First question, would the P0449 code be delayed by the potential "not ready" status that may have just changed or would it have come back right away weeks ago after the previous reset if there was a fault?

So today after resetting the code again the truck was driven a total of 45 miles on the highway (55-60 mph) as suggested by the emissions inspector to get the EVAP sensors "ready". Unfortunately it was segmented twice by short on/off ramps to get the miles.
Got home with about 70 miles from reset and OBED EVAP seen as "not ready". Not planned, but the gas tank started out as full which is contrary to what was advised above.

Any idea how many miles or amount of time is needed to get the sensors active?

Maybe I need to chase other parts in the system while waiting it out.

Click to expand...

50 miles @55 so 25 miles highway trip and return, that should set all but evap might not set, it can take a while, usually you are allowed one "not ready" depending on your state

I don't remember what code it was exactly but one for small leak. I only got it after putting a new oem canister on mine. it would take months to set the light. turns out my new gm part was bad but just saying you are correct. I could drive a month of normal routine and never set a light because it was always unavailable. once it completed its test it set a light.

I ended up putting the old one back on for a few months to confirm it was the can and then bought a 2nd new one to fix it.

on a side note, I thought as long was everything else said passed and evap said not ready you could still pass emissions? it's the fault code set and/or the other ones not being ready that fail it. In theory you could catch it between the time everything else in ready and evap is still unavailable but not failed and pass?

Conditions for Meeting a COLD START

"The ignition voltage between 11-18 volts."
Charging system must be working normally.

"The barometric pressure (BARO) is more than 75 kPa."
No starting up in the eye of a hurricane, or in the mountains.

"start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F)"
"start-up intake air temperature (IAT) is between 4-30°C (39-86°F)"
"difference between the IAT and the ECT is less than or equal to 6°C (10.8°F)"
So if the engine is either dead cold, or fully warmed up, you are wasting your time.
Also, try popping open your hood for quicker cooldowns.

"ambient air temperature is between 4-30°C (39-86°F)"
Winter and summer won't make this any easier.

"Fuel level is between 15-85 percent"
Or, as far away from both FULL and EMPTY as reasonably possible.

"Without RPO LMG--The fuel alcohol content is less than 15 percent."
If your engine lacks have flex fuel capability, hope your gas station isn't skrewing with you.

"With RPO LMG--The fuel alcohol content is less than 87 percent."
Flex fuel capability = no worries?

Driving more than 5min at a time defeats the above.

j91z28d1 said:

I don't remember what code it was exactly but one for small leak. I only got it after putting a new oem canister on mine. it would take months to set the light. turns out my new gm part was bad but just saying you are correct. I could drive a month of normal routine and never set a light because it was always unavailable. once it completed its test it set a light.

I ended up putting the old one back on for a few months to confirm it was the can and then bought a 2nd new one to fix it.

on a side note, I thought as long was everything else said passed and evap said not ready you could still pass emissions? it's the fault code set and/or the other ones not being ready that fail it. In theory you could catch it between the time everything else in ready and evap is still unavailable but not failed and pass?

Click to expand...

"Not ready" was reported as a failure and 90 days to retest. I don't know what happens if it's not ready again.

Doubeleive said:

50 miles @55 so 25 miles highway trip and return, that should set all but evap might not set, it can take a while, usually you are allowed one "not ready" depending on your state

Click to expand...

It's hardly possible to drive 55 on highways here without getting run over.
It showed three "not readys" ; Evaporative system, oxygen sensor and oxygen sensor heated.
The code reset was related to Evap system.

Marky Dissod said:

Emissions Test Issue

Looking online, that code seems to mainly indicate a bad vent valve? I believe I have seen that mentioned somewhere here as well.. The "vapor canister purge valve" was swapped out for a new oem replacement and the code reoccurred three or so weeks later. GM called it vapor canister purge valve...

www.tahoeyukonforum.com

Conditions for Meeting a COLD START

"The ignition voltage between 11-18 volts."
Charging system must be working normally.

"The barometric pressure (BARO) is more than 75 kPa."
No starting up in the eye of a hurricane, or in the mountains.

"start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F)"
"start-up intake air temperature (IAT) is between 4-30°C (39-86°F)"
"difference between the IAT and the ECT is less than or equal to 6°C (10.8°F)"
So if the engine is either dead cold, or fully warmed up, you are wasting your time.
Also, try popping open your hood for quicker cooldowns.

"ambient air temperature is between 4-30°C (39-86°F)"
Winter and summer won't make this any easier.

"Fuel level is between 15-85 percent"
Or, as far away from both FULL and EMPTY as reasonably possible.

"Without RPO LMG--The fuel alcohol content is less than 15 percent."
If your engine lacks have flex fuel capability, hope your gas station isn't skrewing with you.

"With RPO LMG--The fuel alcohol content is less than 87 percent."
Flex fuel capability = no worries?

Driving more than 5min at a time defeats the above.

Click to expand...

Deleted comment after reading other posts.

See post #14 from @mikez71 and #17 from @Marky Dissod; for an evap system test to run, ALL of the "Conditions" listed for a cold start must be met. For example, the fuel tank cannot be full; there needs to be air in the tank for the fuel tank pressure sensor to tell if the pressure is changing. Then it's a matter of driving it with varied speeds, etc., as stated in the procedure. Sometimes not all of the procedure needs to happen for it to run the pass/fail test.

The first time it runs the evap test successfully it will either "pass" that event, or if it fails it will set a pending code which you won't see unless your scanner is capable of showing pending codes. If there's a pending code and it fails a second test it will light the money (MIL/CEL) light.