I have a 99 Blazer with 4.3 4x4, and it has had a "small EVAP leak" for several years. When it comes time for the inspection, i fill-up and clear the codes.
Im attempting to get all of the monitors to a ready status. The process of getting all the monitors to ready, is getting hung up?

I looked at the live data on the scanner, and it reads "error" for the second air? Im guessing there is a problem there, and the PCM is just not proceeding ?
I have done some checking, and the air pump is running at startup as it should. I replaced the vac hose to the valve just after the pump. I can see no hoses melted, and the 10a fuse next to the 30a maxi looks good.
Not sure where to go from here, and any assistance would be appreciated.
Thanks,
JW

 

I have since opened the hose at the tee. I had exhaust from the drivers side, and pulled the check valve. The check valve was not sealing completely. I changed the valve with a new one, but it hasn't changed the"error" value on the scan tool under second air? Any suggestions?

 

Some of the monitors, especially EVAP & secondary air, can take a while to run and complete their tests if the General Motors Driving Cycle is not perfectly duplicated. During the driving cycle, the PCM is "looking" for a certain set of events to happen in a certain order. Many of the steps have several different basic requirements such as: (among others) The EVAP monitor will only run if/when fuel level is between 15% & 85%. If it doesn't meet that, it skips the test. Each step must be duplicated exactly as written, or the test(s) will not run and complete. Performing it correctly forces each monitor to run and complete its test. If a monitor does not complete during the cycle, the PCM will continue to "watch" for the necessary events to happen to run the test again. If the driver does not duplicate the requirements, the test will abort and the PCM starts over "looking" for the requirements to be duplicated. Sounds complex because it is. In a nutshell, that's how it works, and why some monitors can take a while to complete. As for the "error", it might be a software glitch in the scan tool. It's rare, but it does happen from time to time.

 

Than you for your reply, and insight. I have erased the codes, and will start over.
I will keep you posted.
Again, thanks.

 

I drove many, many miles, but could not re-set the last four monitors from "inc". I finally got fed up and took the car to be diagnosed at a shop. I was told the problem was, the air pump was running, but not flowing enough air into the system.
I installed the new pump (no codes present) and 4 monitors "incomplete" and then started the car.
I first noted the new pump being more audible. The old one was almost silent, unless you put your ear next to it.
Next thing i noted, was the length of time that the new pump runs, was longer at start up.
I also see changes in the data on the live screen relating to fuel trim, and o2. It looks to relate to the pumps operation. I was not watching for this with the old one.
The "error" value is still present for second air. I'm driving the car, but not seeing any change. no additional monitors are setting. I still have the 4 remaining.
Starting to feel like a little ball, in tall grass here.

 

Shouldn't need to drive that far. A driving cycle can be completed in ~15 minutes. If all monitors haven't completed, the specified drive pattern has not been duplicated. At least one, possibly more, of the steps have not been duplicated.

 

try tightening the gas cap .could be that simple. I had the same problem a while ago and for the life of me could not figure out what it was. finally I said to myself start at the beginning. check one thing at a time and low and behold...ta daa....gas cap was loose..problem solved ...no more evap code.

 

Been driving everyday withe the new air pump, but it will not reset the last four monitors to "ok" status on scanner. I really only need two more to go to "ok" to pass.
Do the O2 sensors have something to do with second air?
They seem to pass, and read "ok" not sure what else to do

 

The PCM uses oxygen sensor data when the secondary air monitor runs. If an oxygen sensor fails, the secondary air monitor will not complete its test.

Are there any current or pending DTC's in memory? Is the check engine light on? If the answer to either one of these is "yes", the problem must be repaired first. If not, you haven't duplicated the driving cycle correctly.

 

I have no codes pending or set, and the check engine light is not on.
Should I just put new O2 sensors in?