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Secondary Air: Diagnosing and Removal

This is a discussion on Secondary Air: Diagnosing and Removal within the General Help forums, part of the LSx Technical Help Section category; The secondary air system on our cars seems to be a common problem area. For those of us that have ...

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    Secondary Air: Diagnosing and Removal

    The secondary air system on our cars seems to be a common problem area. For those of us that have deleted it, the problem is no more. However, many cars have to maintain it for emissions reasons. The sole purpose of the system is to inject fresh air into the exhaust manifolds on cold start up. This is accomplished by activating an electric air pump that pulls air from the filter box and routes it through a vacuum controlled diverter valve, through a check valve on each side of the engine, and finally into the manifolds. The system only operates for 1-2 minutes after start up and serves to assist the catalytic converters into coming up to operating temperature faster.

    Here are the basic components of the system as viewed from under the hood. The check valves are circled in RED, at the rear of the FRC in BLUE are the diverter valve and vacuum solenoid, and to the right in YELLOW is the air hose from the pump.




    Removing the FRC, you can see the vacuum solenoid circled in YELLOW and the diverter valve circled in RED.




    The other primary component is the air pump. This is located in front of the left wheel and is accessed by removing the splash guard from beneath the vehicle.







    In the event the secondary air system ceases to operate correctly the SES light will be lit and a code can be retrieved with a scanner. The procedure for diagnosing the system is as follows:

    1. First thing to check is if the pump runs after cold start up. On the left side of the engine compartment (right side from the front of the vehicle), over the top of your driver side wheel well, is a hose. Disconnect the hose at the union and start your car. There should be air blowing from the hose which runs up from the front end.

    2. If there is no air blowing, you will need to check the fuse and relay to ensure that there is power to the pump. These are located in the electrical boxes on the right side of the engine compartment. The relay is in the left box and the fuse is in the right box. Both are labeled "AIR PUMP". You can also probe the connection at the pump to check for power.





    3. If power checks out, but the pump is still not pushing air, you will need to inspect the pump. It is possible that it has simply failed, a hose has become disconnected, or there may be a blockage in one of the hoses. Remember -- the pump only runs on cold start up for a short period of time.

    4. If the pump is running correctly and you have air at the driver side hose over the wheel well, then you need to check if the air is flowing to the exhaust manifolds. On each side of the engine there is a tube bolted to the manifold. This runs up to the check valve onto which is clamped a rubber hose. Disconnect each clamp and pull the hose. Again, on cold start up you should have air blowing from the hoses.

    5. If air does not blow from the hoses you need to check the solenoid and diverter valve that are located on top of the engine. The electric solenoid allows a vacuum signal to open the diverter valve such that air flows to the manifolds through the check valves. The diverter valve has three (3) hoses atatched to it, one being the hose from the pump and two going to the manifolds on each side of the engine.

    6. Begin by checking for vacuum by removing the hose at the top of the diverter valve. If there is no vacuum present, either the solenoid is bad, a fuse is blown, or the circuit is open. It is also possible that the vacuum source line may be a problem so this should also be checked. If there is vacuum then it is likely that the diverter valve has failed. It should be removed from the vehicle and inspected with a handheld vacuum pump before replacement.

    7. If all of these components are working correctly, then the most likely culprit is that the check valves or manifold tubes are bad, or simply plugged up. The check valves can be purchased from a dealership or most auto parts stores. The tubes can be cleaned of carbon buildup should this be the problem.


    REMOVAL:

    In the event you wish to remove the secondary air system in its entirety, it is quite simple to do. Please note that you will need to have your PCM re-programmed to delete the system or you will be driving around with your SES light on all the time.

    The air pump is pulled by disconnecting the electrical connector and two hoses. Access is again from beneath the vehicle. It is tight working quarters and a hose pick was quite useful for both the electrical harness and hoses.





    I found that it is easiest to simply snap off the rubber biscuits from the clips as there was not room to slide the pump off of them. I then removed the clips as well to avoid any potential for a rattle. The clips have a tower on the top side to protect the wire harness which runs directly above the pump cavity. Here is a view of the pump once it is out of the car.





    Back up top, the fuse and relay were removed from the electrical boxes.








    The hoses to and from the air pump and diverter valve can then be removed. It is advisable to use a flat blade screw driver to press out the clips on the cowl seal before you work in this area -- they are sharp and will make you bleed. Once the hoses are removed, this leaves a hole in the side of the airbox from the fresh air feed. I found a Chrysler "Master Cylinder Gasket" in the HELP! section at our local Autozone that fits the hole perfectly. It is P/N 42081 and actually does not look too bad installed in the side of the SLP lid.





    After the hoses are removed, both the solenoid and diverter valve can be unplugged and unbolted and also removed. Note that there is a 15 mm bolt on the back side of the head that has to be loosened (not removed) to pull the bracket for the diverter valve. This should then be snugged back down as it may have a ground wire attached to it as well. Access is tight, but you can get to it with a wrench.

    After the components are all removed, you should tape up any open electrical connections and also plug off the vacuum source line that attached to the solenoid. The bracket for the solenoid can also be unclipped from its holder on the intake manifold. Again, you will need to delete the secondary air system via tuning to complete the process.

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    Moderator Cutlass's Avatar
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    Great write up and pictures!! I'm add this to the tech stickies.
    One additional note. The older AIR system, like the one on my '99 is a little simpler. Just a pump, hoses, and check valves. There isn't any diverter valve or vacuum control solenoid.
    Last edited by Cutlass; 02-05-2010 at 06:36 PM.

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    I failed emissions for P0410. So I replaced the solenoid, no change. The fuse/relay was fine. I went under the car and checked the air pump and found that is was only moving a little air. So I ordered this [ame="http://www.amazon.com/gp/product/B000Q0PG5S/ref=oss_product"]http://www.amazon.com/gp/product/B000Q0PG5S/ref=oss_product[/ame] I assume the section where the hoses attach you keep and put on the new unit. Man its tough getting to the pump. Did you take the whole splash guard off? Or just work in the little section the folds down?

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    Quote Originally Posted by vassago View Post
    I failed emissions for P0410. So I replaced the solenoid, no change. The fuse/relay was fine. I went under the car and checked the air pump and found that is was only moving a little air. So I ordered this http://www.amazon.com/gp/product/B00...ef=oss_product I assume the section where the hoses attach you keep and put on the new unit. Man its tough getting to the pump. Did you take the whole splash guard off? Or just work in the little section the folds down?

    I believe I removed it completely to gain some more working space. It was not all that difficult to get out of the way if I recall. Did you check your inlet tube to make sure that there are no blockages? That would cut down on your airflow quite a bit.

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    I disconnected the inlet from the air lid and turned the car on. I could not feel any air being sucked in when I held my hand over it.

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    Quote Originally Posted by vassago View Post
    I disconnected the inlet from the air lid and turned the car on. I could not feel any air being sucked in when I held my hand over it.
    Was the pump definitely running? I think I would remove the pump from the car and run a set of jumper wires to a battery to see what it does.

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    Where would one go to get the PCM reprogrammed when the system is removed to keep the service engine soon from staying on ?

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    You could do a mail order tune from one of our site sponsors, TunedByFrost.com
    Look him up here, his screen name is Frost


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    I like those black covers!

    So, if you have no problems with the secondary air system, would you suggest leaving it in? I'm sure it cleans up the engine bay, but that isn't an issue for me, I only plan to get the rail covers and head plate from underneath the hood.

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    Quote Originally Posted by KMdef9 View Post
    So, if you have no problems with the secondary air system, would you suggest leaving it in?
    Yes. Generally people only remove it because of weight, cleaning up the engine bay, installing offroad headers, or there is a problem with it that they don't wanna fix.

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    Quote Originally Posted by Cutlass View Post
    Yes. Generally people only remove it because of weight, cleaning up the engine bay, installing offroad headers, or there is a problem with it that they don't wanna fix.
    Are there certain brands that fall into this category, or do all of them? (It'll be in the plans next year or 2)

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    Almost all brands offer both off road and emissions friendly headers, so you can still choose to keep your AIR with headers.

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    Well after about 3 hours, which is probably good for someone like me, I got the pump replaced. Once I had it out, I removed the section with the intake/output section and turned the car on, no motor spin at all. Plugged the new one in and started the car and zoom it spun right up. So I am going to disconnect the batter to reset the check engine light and see how it does.

    Thanks again for all the info in this thread. I was someone that never thought I could fix my own car, but with the help from this site, I have been able to change that.

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    Quote Originally Posted by vassago View Post
    Well after about 3 hours, which is probably good for someone like me, I got the pump replaced. Once I had it out, I removed the section with the intake/output section and turned the car on, no motor spin at all. Plugged the new one in and started the car and zoom it spun right up. So I am going to disconnect the batter to reset the check engine light and see how it does.

    Thanks again for all the info in this thread. I was someone that never thought I could fix my own car, but with the help from this site, I have been able to change that.

    Good to hear that you were able to fix it on your own. There are lots of great members on here who are always willing to share their experience.

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    where can you get a block off plate for the manifolds then??

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    thunder racing carries them but you can also trace out the flanges onto some aluminum and cut your own if you have the means to do so. Pretty easy to make them.

    part number at thunder racing: 99-86SP
    Cost $9

    Not sure if that comes in a 2 pack or not so you may want to shoot them an email. They say 2 required which looks like you'd need to order 2 but for some reason I was thinking that there were 2 in the package. Ask them to be sure. Please update the thread if you find out.
    Last edited by 0rion; 06-08-2010 at 11:50 AM.

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    My SES lite came on and I had the codes checked. Code for secondary air is what they told me. That was the only code stored and I would like to know if there is anything with the secondary air that would affect the way the engine runs. The car seems to bog down under a load at low rpm. This problem comes and goes.

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    Senior Member Too Fast's Avatar
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    Quote Originally Posted by mytuneport View Post
    My SES lite came on and I had the codes checked. Code for secondary air is what they told me. That was the only code stored and I would like to know if there is anything with the secondary air that would affect the way the engine runs. The car seems to bog down under a load at low rpm. This problem comes and goes.
    No, nothing in the AIR system would cause that. A dirty MAF jumps instantly to my mind, tho. It'd be the first thing I would do, get some MAF cleaner and spray clean that puppy. Don't physically touch the wires. And the check valves go bad in the AIR system, they can set codes. What was the actual code?

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    Quote Originally Posted by Too Fast View Post
    No, nothing in the AIR system would cause that. A dirty MAF jumps instantly to my mind, tho. It'd be the first thing I would do, get some MAF cleaner and spray clean that puppy. Don't physically touch the wires. And the check valves go bad in the AIR system, they can set codes. What was the actual code?
    not so quick if the check valve sticks open or if the pump is running all the time I'll create a huge false lean condition. PCM will dump more fuel trying to correct it and make the care too rich which will cause bogs.


    What's the code number?

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    Quote Originally Posted by 0rion View Post
    not so quick if the check valve sticks open or if the pump is running all the time I'll create a huge false lean condition. PCM will dump more fuel trying to correct it and make the care too rich which will cause bogs.


    What's the code number?
    I've never encountered either condition, that's why I said what I said. What you say is possible, but not a likely scenario. I've worked on cars since I've been 18, and have never seen a stuck on air pump. However, someone will come on here and tell me that they have LOL. You never know what happens when people do their own wiring, I've seen some real winning self wiring....

    But it would create a false lean like you say, and we both repeat, what is the actual code?

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