Vehicle will not run Evap Monitor

[TexasWhiskey]

2007 Silverado 4.8L Crew Cab (New Body) had a P0455 code AND gas pump was shutting off. Seemed like opposing issues. 18 year old Silverado so just decided to shotgun it since I only had 2 days left in Sept to get my inspection.

Replaced Purge Valve, Replaced Vent Valve, Replaced Charcoal Canister, Replaced gas cap. Engaged vent valve to close it, smoke tested system from the schrader valve port near the purge valve. Smoke test perfect, no leaks, and when I removed gas cap smoke boiled out.

Cleared code.

Ok here is issue. I have been driving for 5 days now (city, highway, multiple cold cycles, idling, ALL) for about 150 miles. Fuel tank is between 1/4 and 3/4 tank. I have 5 of 6 Evap Ready but the Evap Monitor will not show Ready. It shows Not Ready or INC on 2 different readers. The P0455 code is fixed as it has not returned.

How can I get the ECU to run the test? I spoke to mechanic and he immediately expressed his frustration with not having that command.

What else is needed to have all the requirements to run the Evap test?

 

[Fless]

See the link below from @mikez71 for the requirements. Specifically note that it will only run on a cold start, and the difference between the IAT and the ECT is less than or equal to 10.8°F.

Emissions Test Issue

I recently had an error code related to small evap leak and circuit failure. I cleaned the gas tank filler neck and cleared codes about a week ago. No codes have returned. I went in for the biannual emissions test today (plug in test) and it failed because it noted three "not ready" notations...

www.tahoeyukonforum.com

 

[j91z28d1]

good thing is you don't need that pass to pass most emission testing if it's the only one that says unavailable. fail is different thou.

mine can take a month to pass of normal driving. I replaced the charcoal canister as a precaution and didn't realize it was split at the seam out of the box. it took over a month to even set a fault code. so long the warranty was past and I had to buy a 2nd new one haha.

 

[Doubeleive]

2007 Silverado 4.8L Crew Cab (New Body) had a P0455 code AND gas pump was shutting off. Seemed like opposing issues. 18 year old Silverado so just decided to shotgun it since I only had 2 days left in Sept to get my inspection.

Replaced Purge Valve, Replaced Vent Valve, Replaced Charcoal Canister, Replaced gas cap. Engaged vent valve to close it, smoke tested system from the schrader valve port near the purge valve. Smoke test perfect, no leaks, and when I removed gas cap smoke boiled out.

Cleared code.

Ok here is issue. I have been driving for 5 days now (city, highway, multiple cold cycles, idling, ALL) for about 150 miles. Fuel tank is between 1/4 and 3/4 tank. I have 5 of 6 Evap Ready but the Evap Monitor will not show Ready. It shows Not Ready or INC on 2 different readers. The P0455 code is fixed as it has not returned.

How can I get the ECU to run the test? I spoke to mechanic and he immediately expressed his frustration with not having that command.

What else is needed to have all the requirements to run the Evap test?

you can check local ordinance and see if you can pass with one sensor not set, a lot of places allow for it.

 

[MWD_CTSV]

The readiness code for EVAP and others is not just a single test. In many cases it will only run a certain test under certain conditions. In other cases, it is always 'testing' but only certain testing counts towards completeness for the monitor. One of the worst things about some of the readiness monitors (especially EVAP), is that they can take many drive cycles to officially complete. I'm pretty sure most states will allow one emissions readiness test to be incomplete as long as there are no codes.

The TECHII should show actual drive cycle count, so you can know if your last drive counted. In many cases for GM, what you think as a cold start is not really a cold start. It can require no engine run within 6 hours, as well as engine and air intake to match closely. So sitting in the hot sun could allow for the underhood air temp to register much higher than the coolant temp. It can be very painful, but if it is only EVAP that is incomplete and you aren't in CA or NY, I think you will pass if everything else is good. I once drove 150 miles across multiple days trying to match all the conditions for running the tests in the same drive, and it wasn't until the end of the 5th official drive cycle that it finally marked complete. I have also seen EVAP take over 10 drive cycles (GM), for no real reason that I can tell.