Evap Failing to get I/M Readiness-No codes

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I just want to get my 06 9-7x 5.3L to pass the e-test, which is just a check for no codes and I/M readiness. All systems have to run through the required cycles and have passed. My evap is failing to complete. I'm not getting any DTC codes, no MIL, just keep getting "Incomplete" for the evap system in Torque. I've been driving the truck a few days from 3/4 tank to almost empty and still not getting it. The gas cap is a new ACDelco.

Checking the test results, the ones for evap just say "Test either not run or failed to complete" and is just in black. All others were either green (pass) or red (failed).

I fixed a few other issues like a bad MAF and post cat O2 sensor but did nothing to the evap system except the cap (it was broken). Is it possible that the PCM got a tune and those codes/tests turned off? The guy I bought it from seemed to be an enthusiast since the truck is lifted and it had a K&N filter (now a Green filter). Tranny also seems to shift pretty firm. He also owned a turboed Vette.

Any ideas?
 

IllogicTC

Member
Dec 30, 2013
3,452
No codes, but indeterminate results... how many miles have been logged since the last DTC clearing? EVAP usually wants to take a while.

The only other big thing in the air is, assuming no codes show up, if the PCM is not deciding to run the EVAP purging.

I'll post this information here just to have it here.



EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM DESCRIPTION

EVAP SYSTEM OPERATION
The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP canister vent solenoid valve to atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP canister purge solenoid valve ON, open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP canister vent solenoid valve OFF, open, fresh air will be drawn through the solenoid valve and vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP canister purge solenoid valve into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.

Large Leak Test
This tests for large leaks and blockages in the evaporative emission (EVAP) system. The control module will command the EVAP canister vent solenoid valve ON, closed, and command the EVAP canister purge solenoid valve ON, open, with the engine running, allowing engine vacuum into the EVAP system. The control module monitors the fuel tank pressure (FTP) sensor voltage to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge solenoid valve OFF, closed, sealing the system and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay rate is more than a calibrated level on 2 consecutive tests, a DTC P0455 will set.

Small Leak Test
If the large leak test passes, the control module will test for small leaks by continuing to monitor the fuel tank pressure (FTP) sensor for a change in voltage over a period of time. If the decay rate is more than a calibrated value, the control module will rerun the test. If the test fails again, a DTC P0442 will set.

Canister Vent Restriction Test
If the evaporative emission (EVAP) vent system is restricted, fuel vapors will not be properly purged from the EVAP canister. The control module tests this by commanding the EVAP canister purge solenoid valve ON, open; and commanding the EVAP canister vent solenoid valve OFF, open; and monitoring the fuel tank pressure (FTP) sensor for an increase in vacuum. If vacuum increases more than a calibrated value, DTC P0446 will set.

EVAP Purge Solenoid Valve Leak Test
If the evaporative emission (EVAP) canister purge solenoid valve does not seal properly, fuel vapors could enter the engine at an undesired time, causing driveability concerns. The control module tests for this by commanding the EVAP canister purge solenoid valve OFF, closed; and EVAP canister vent solenoid valve ON, closed; sealing the system, and monitoring the fuel tank pressure (FTP) for an increase in vacuum. If the control module detects that EVAP system vacuum increases above a calibrated value, DTC P0496 will set.

CHECK GAS CAP MESSAGE
The powertrain control module (PCM) sends a class 2 message to the driver information center (DIC) illuminating the Check Gas Cap message when any of the following occur:
A malfunction in the evaporative emission (EVAP) system and a large leak test fails
A malfunction in the EVAP system and a small leak test fails
EVAP SYSTEM COMPONENTS
The evaporative emission (EVAP) system consists of the following components:

EVAP Canister
The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.

EVAP Canister Purge Solenoid Valve
The EVAP canister purge solenoid valve controls the flow of vapors from the EVAP system to the intake manifold. This normally closed solenoid is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The solenoid will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.

EVAP Canister Vent Solenoid Valve
The EVAP canister vent solenoid valve controls fresh airflow into the EVAP canister. The valve is normally open. The control module will command the solenoid closed during some EVAP tests, allowing the system to be tested for leaks.

Fuel Tank Pressure Sensor
The fuel tank pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts . As FTP increases, FTP sensor voltage decreases, high pressure equal low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum equal high voltage.

EVAP Service Port
The EVAP service port is located in the EVAP purge pipe between the EVAP canister purge solenoid valve and the EVAP canister. The service port is identified by a green-colored cap.

Code:
Conditions needed to run vacuum EVAP tests


Fuel heated begins to produce pressure. A rise in temperature occurs as the fuel pump gives off heat. Ambient temperature is also a concern. The GM and Ford systems do not use a fuel temperature sensor. Instead, they check intake air temperature (IAT) and compare it with engine coolant temperature (ECT) reading. If they are near each other, the vehicle has not been running. Engineers assume the vehicle has unheated fuel, when meeting these conditions.


Before the tests run, the PCM also checks the vehicle speed and engine load. The tests require the engine to be running, at an idle, with near a zero load. This means there will be a steady vacuum, and fuel will not be sloshing in the tank. Ambient temperature is also considered and must be above 40 degrees Fahrenheit. A high limit, of 100 degrees Fahrenheit, is set for most models. A few vehicles have the upper limit at 86 degrees Fahrenheit. If the temperature is outside these ranges, the tests will not execute.


Other factors include barometric pressure and fuel level. The fuel level must be between 15% (1/4 tank) and 85% (3/4 tank) and steady. If the fuel level is changing, as with sloshing, the tests will not run. The PCM must also be clear of diagnostic trouble codes, to enable the EVAP testing. Because of these specific requirements, the vehicle may not test the EVAP system on every drive-cycle. This can cause the check engine light to turn off temporarily, although a code is still present in history.
The second piece of text mentions ambient temperature must be above 40 fahrenheit. Considering your location, this may be an issue. Parked outside or garage queen?
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
It's parked outside and been below freezing lately. It's been about 200km since the last code clearing after replacing the O2 sensor. Some good info you posted. Even if I were to find a heated garage to run it in and it eventually passes, will it keep that pass until I drive it to a test facility?

What a PITA this test is! The engineers that thought of this test were obviously not from Detroit.
 

Knucklehead

Member
Jul 23, 2014
55
We own 7 GM trucks and SUVs. The longest one to set my evap IM was about 2 months. That was driving a about 5-8 miles daily. The quickest was a day of driving around town.

I'm in the same boat as you right now. I'm waiting on my evap IM to set on my 03 sierra so I can smog it. I already ran 3/4 tank to empty and filled back up. Hopefully it come soon.
 

IllogicTC

Member
Dec 30, 2013
3,452
I think it should hold that pass until a DTC is cleared, the battery is disconnected, or an EVAP-related DTC sets.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I'll put it in the garage at work, let it sit a few hours and them let it idle until warm. This better work because I am on my second temporary 10 day permit and they don't allow more after that. And I can't get a conditional pass because I need a full pass to get it registered.
 

IllogicTC

Member
Dec 30, 2013
3,452
Mooseman said:
I'll put it in the garage at work, let it sit a few hours and them let it idle until warm. This better work because I am on my second temporary 10 day permit and they don't allow more after that. And I can't get a conditional pass because I need a full pass to get it registered.
I am surprised that the guy checking the readiness indicators didn't mention that there may be a reason there are no fault codes but yet your EVAP isn't testing.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I haven't taken it in yet. I hate having anything fail and pay for a retest. I doubt the kid at Mr. Lube doing the testing even knows what an evap is. All they do is plug in the computer, check for codes and the I/M readiness. That's it. Computer spits out a certificate and it's recorded back at the MTO.

Used to be a full tailpipe test under load until they changed it to this last year. They weren't getting enough fails.
 

IllogicTC

Member
Dec 30, 2013
3,452
Mooseman said:
They weren't getting enough fails.
Maybe. They hire some statisticians who say, "1 in x should fail." Well, if everyone in the area is keeping their stuff maintained decently, it'll fall below that number-crunched quota and it'll be believed that it's because they're not testing the right way rather than just a positive reaction and reduction in failed systems in response to the law currently in place.

It'd be like posting police in an area in response to crime rate, and when crime rate goes down, they swap methods and do "stop and frisk" because there SHOULD have been X-amount of crime, dangit!
 
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Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
Anyway, I'll be taking it in the garage tonight at work. I'll be so paranoid that I won't even climb into the truck so that the fuel won't move in the tank. I need this to work! :hissyfit:

Wish me luck!
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
Well shit, it didn't work. Idled it for over an hour in the warm garage. I'll try and drive it today as it is just above 40f. Working again tonight so I'll try another strategy by letting it sit all night in the garage, starting it in the morning, idling it for a few minutes and then drive it out normally, trying to simulate a normal drive.
 

Knucklehead

Member
Jul 23, 2014
55
GM has a fill/empty cycle. First is 3/4 tank then on form there. I'm not sure if it's the same for TB as it is for fullsizes.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
Well, I had a partial success today. Some of the tests completed successfully but still no readiness. Like you said, it probably has to go through a few more cycles (started at just under 85% tank) but I am losing my window of mild weather. Temps are dropping tonight so I'll park in the garage again tonight. This afternoon I started the truck, let it warm up and then drove it highway and city for an hour.

It has to complete by the end of this week when my temporary permit expires. What pisses me off is that it takes just a 20 minute drive for my son's POS 01 Honda Prelude to go into full readiness :hissyfit:
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
Just an update. Looks like I worried about it for nothing. Taled to the tech doing the test and he says as long as there is only one test that is not ready, it will pass, and it did. All is well.

BTW, the evap is still not ready.
 
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IllogicTC

Member
Dec 30, 2013
3,452
Mooseman said:
Just an update. Looks like I worried about it for nothing. Taled to the tech doing the test and he says as long as there is only one test that is not ready, it will pass, and it did. All is well.

BTW, the evap is still not ready.
Now that's the kind of information that's important to have. :rotfl:
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I went with what was on the MOT Drive Clean website said, which was BS. It said that if you fail a readiness test, you only get a conditional pass for a year and that you can't have that for an ownership transfer, must have a full pass. Neither was true.
 

Knucklehead

Member
Jul 23, 2014
55
Mooseman said:
Just an update. Looks like I worried about it for nothing. Taled to the tech doing the test and he says as long as there is only one test that is not ready, it will pass, and it did. All is well.

BTW, the evap is still not ready.
What state is this in?? I heard the same thing for California and also heard it has to fully link up completely. I'm going to call around tomorrow gotta get my smog for my pink slip.
 

C-ya

Member
Aug 24, 2012
1,098
Knucklehead said:
What state is this in?? I heard the same thing for California and also heard it has to fully link up completely. I'm going to call around tomorrow gotta get my smog for my pink slip.

Knucklehead, you must be on a device other than a computer and using Tapatalk or the like. Mooseman is from Canada, eh.
 
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Knucklehead

Member
Jul 23, 2014
55
yes. I'm using my tapatalk from my phone. Haha.

And just a heads ups. For the OP.

I have been waiting on my evap I'm to set. It has been about 1.5 months since I started to wait for it.

I swapped my gas cap with one from my other Chevys. It set with in 5 miles of driving it that morning. I Went strait to the smog shop and got my smog cert.

Try putting a new gas cap on it OP.
 
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Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I did, as per my first post. Brand new ACDelco. Anyway, it's irrelevant now.
 
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j-bone

Member
May 5, 2014
83
Dragging up an old thread here , i'm in the same boat as moosman test is due the end of the week. Been over a month since it failed due to the battery being disconnected ! drove it on the highway many times have had fair weather for 3 of the 4 weeks any tricks !
no stored codes either !
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
I have another thread on the same issue. Because of the O2 sensor not going to ready, I had to force the evap to complete by using my Tech 2. I guess in your area you need all tests ready? If so, you might have to do the same thing. Or search the net for "GM readiness test drive procedure" which should bring up the drive cycle to get it it pass. Or you might have to take it to a shop or dealer to force it with the Tech 2.
 

j-bone

Member
May 5, 2014
83
All other tests are complete if that's what you mean by 02 sensor being ready ?
I do have access to a pretty powerful snap on scan tool I should see if that will force the test procedure.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
It might. Hopefully it does. Makes the process much easier.
 

j-bone

Member
May 5, 2014
83
Bringing this back from the dead ....
does anyone know where / how to force readiness with the tech 2?
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
IIRC, in special functions, bay tests.
 

mrrsm

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@j-bone... Any chance you could do a "How-To Article" write up for the Tech 2 Section that covers all aspects of the Problems & Diagnosis and Testing Procedures with Tech2 "Step By Step" Screen Images for the GMT360s ?
 

j-bone

Member
May 5, 2014
83
I'm adding some follow up information to those who find this thread for help .
first off those who have a tech 2 close please see the following post before starting the test https://gmtnation.com/forums/threads/fix-tech-2-reboots-if-engine-started.16563/#post-583460
second the test needs to do done when the engine is cold , but I found out the hard way letting the car sit over night or 24 hours will cause the pcm and other modules to go into sleep mode and just turning the key on will not wake them up I sat for 15 minuets waiting for the tech 2 to prompt the next step before aborting the test.
so start the engine and let it run for 10-15 seconds then shut off and start the test as normal , it didn't seem to be a problem . also as noted make sure you have 1/4-3/4 of gas .

The evap test its self passed for me but the driving portion failed , I drove the 9 miles before the time ran out so i'm a little confused and have to try another day , any input as to why this failed would be helpful.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,262
Ottawa, ON
And it MUST be above freezing temperatures.

Possibly you didn't keep it at the speed you were supposed to? I had to drive it steady at highway speed for a portion of the test. The Tech 2 should prompt you.
 

j-bone

Member
May 5, 2014
83
Hmmm I may have skimmed the prompt screen and missed that but I was on the highway for most of the test .
I’ll report back when I try the test again .
The first part of the test was in park and keep between 1800-2200 rpm which passed .
 

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