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Old 01-04-2018, 01:48 PM
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Default GM EVAP Service Bay Test

I had to fool with a Chevy van the other day. It needed a bunch of work, but also had a bad purge valve. In order to get it through NC State Inspection, I needed to get the Monitors to run. I ran the Service Bay Test to do it.
I recorded the data while I did it. I figured I'd post the data to show how this test runs.
Remember that this Test takes place after the key is turned off. It requires 10 minutes and 5 miles of driving to warm the fuel tank up. Then it needs to sit and cool off, so vacuum can develop.
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Old 01-04-2018, 07:18 PM
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Cool.

Is this now an option to see the data and log it during the testing process?
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Old 01-04-2018, 07:28 PM
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Cool.

Is this now an option to see the data and log it during the testing process?
You know, I don't know if that's available or not. That's not how this was recorded anyway. Once you get past the high idle portion of the Service Bay Test and start the driving portion, the car is done looking for commands from the scanner. You can back out of the test and watch live data. That's what I did here because I wanted to watch all the monitors run.

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Old 01-04-2018, 07:31 PM
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Originally Posted by Joe Rappa View Post
You know, I don't know if that's available or not. That's not how this was recorded anyway. Once you get past the high idle portion of the Service Bay Test and start the driving portion, the car is done looking for commands from the scanner. You can back out of the test and watch live data. That's what I did here because I wanted to watch all the monitors run.

Joe
I was not aware of this. It would be nice to be able to see that info during the testing process so you can see if it's hitting the correct marks.
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Old 01-04-2018, 07:42 PM
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Quote:
I had to fool with a Chevy van the other day. It needed a bunch of work, but also had a bad purge valve. In order to get it through NC State Inspection, I needed to get the Monitors to run. I ran the Service Bay Test to do it.
I recorded the data while I did it. I figured I'd post the data to show how this test runs.
Remember that this Test takes place after the key is turned off. It requires 10 minutes and 5 miles of driving to warm the fuel tank up. Then it needs to sit and cool off, so vacuum can develop.
So after evap system repairs you only need to drive or run a vehicle for 10-15 minutes and then running the GM Evap service bay test for 35 minutes KOEO will also complete that stubborn EVAP monitor as well as giving you a general pass -fail for the service bay test result? Did you have to hook up a battery maintainer so them damn rotten GM DRLs don't drain the battery? The present temperature here in Illinois is around 0 degrees, so I don't think the gas tank temperature would increase enough to run the test
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Old 01-04-2018, 08:18 PM
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Originally Posted by Witsend View Post
So after evap system repairs you only need to drive or run a vehicle for 10-15 minutes and then running the GM Evap service bay test for 35 minutes KOEO will also complete that stubborn EVAP monitor as well as giving you a general pass -fail for the service bay test result? Did you have to hook up a battery maintainer so them damn rotten GM DRLs don't drain the battery? The present temperature here in Illinois is around 0 degrees, so I don't think the gas tank temperature would increase enough to run the test
Actually the Test runs after you shut the car off. The whole test runs like this:
Make sure the EVAP Monitor is not completed.
In the Functional Test Menu on a GM vehicle, select EVAP Service Bay Test.
The scanner requests you hold the vehicle at high idle. It actually gives you a min/max, but you can ignore that. It just needs to be high idle. Hold it there for 10 minutes, or until the scanner shows that portion of the test is complete.
Now, if the car is older than around 2006, that is the limit of the test, and the scanner will tell you if it passes or fails.
If the car is newer, and uses EONV (Engine Off Natural Vacuum) to test the car, it will tell you to drop it in gear and go for a ride. You may have to drive 10 minutes and 10 miles to warm up the tank.
Then the scanner will tell you to shut the car off. You don't need to do it immediately, so drive back to the shop and shut it off. This is the portion of the test that is recorded above.
Here's how you know of it is in EONV System. Answer is found in the Mode 6 section of your service info.
This car also specs that it has to be over 32F for the test to run.
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Old 01-05-2018, 07:13 AM
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Thanks Joe for the good description of how the service bay test works , but my question remains...Will running the GM Evap Service Bay test besides a pass fail result for this test run, also complete the Evap Monitor so you can just run The Turd over to the test lane sooner than a couple days later.
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Old 01-05-2018, 07:23 AM
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To answer your question Wit, yes it will. Even the older test where you didn't have to drive the vehicle would set the Readiness Monitor. Several other makes also allow you to do this.
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Old 01-05-2018, 08:31 AM
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Once the key off portion of the test runs, does the scanner **** out and show NO DATA....
We have no way of knowing exactly WHEN it will complete and satisfy itself
This necessitates saving a movie every one or two minutes to see what it was satisfied with before it shuts down
In other words, does it STILL DUMP THE SAVED DATA FROM THE BUFFER-??
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Old 01-05-2018, 02:24 PM
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thanks for posting this joe ,it always helps seeing screen shots. does the pcm look for the 10 minute and 5 miles time to confirm the tank is warmed up? being a diesel guy I'm not sure if there's a fuel temp sensor.
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