Code E49 Air Injection System Fault
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HT4100 4.1, 4.5, 4.9 Discussion, Code E49 Air Injection System Fault in Cadillac Engine Technical Discussion; 1990 Deville 4.5 I got the check engine light twice and both times E49 reappears. I did some tests on ...
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    Cristofo's Avatar
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    Code E49 Air Injection System Fault

    1990 Deville 4.5

    I got the check engine light twice and both times E49 reappears. I did some tests on the air check valve and egr valve to try to eliminate things and here is what I found.

    Air Check Valve (car warm and idling) - When I removed the rubber hose from the end of the check valve it was making a loud "sputtering" air sound...I put my thumb over the opening to see which direction the air was flowing and there was vaccum, in towards the front of the car into the front manifold. It wasnt a constant suction, more like pulsating suction (off/on).

    EGR Valve (car warm, not running) - Pushed up on the diaphram and it seemed to take quite a bit of force to push and keep it up. It says in the manual that it will take moderate force to move the diaphram up, and Its hard for me to gauge this. I went into pepboys to see how a new egr valve felt and it was noticeably easier.

    I removed the metal air pipe (by accident) that is connected to the check valve and I cannot get the check valve to unscrew...I hope i dont need to buy a new metal tube because Im sure they're hard to get. The "bung" that is in the front manifold has a piece of the thread missing so Im not even sure the tube was tightly sealed, it came out without me unscrewing it from the manifold. Could this be the issue?

    Any advice? I did search endlessly on these topics and I cant really find what Im looking for.

    Thanks!

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    drewsdeville is offline Cadillac Owners Master
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    Re: Code E49 Air Injection System Fault

    You checked the one check valve to the manifold. Sounds like it's fine. There is also another on the line that runs from the diverter valve to the cat.

    On the diverter valve, pull the hose that leads to the manifold and the one in the back that leads to the cat. Leave the other two on. Start the engine cold. Which port is the diverter valve dumping air? Is there air coming from both ports or just one?

    Check again when engine is warm.

    That tube leaking could cause skewed O2 sensor readings, which are what the PCM uses to gauge AIR system operation.

    We had a discussion on the AIR system's operation a while back. I've written up an in depth description in this thread:
    http://www.cadillacforums.com/forums...solutions.html

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    Re: Code E49 Air Injection System Fault

    Thanks Drew, I'm going to do those tests today. My main concern is to fix the metal pipe that goes to the front manifold. I hope an autoparts place has that fitting that screws into the manifold...If I cant replace it I may temporarily plug the manifold until I can order a new one. I think my last resort will be to a local junkyard.

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    Re: Code E49 Air Injection System Fault

    I read that the thread is a 3/8" NPT but what size thread goes into the manifold itself? I need that adapter/coupling that connects the manifold to the air injection pipe.

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    Re: Code E49 Air Injection System Fault

    I bought a 3/8" plug, plugged the manifold, removed the check valve and capped the hose.

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    Re: Code E49 Air Injection System Fault

    The car runs better but after driving for 30 min the SES light came on. Code 49 again! its been raining so I didnt get to check the diverter valve operation yet. This is a pain in the ass! I'm getting ready to bring it to Cadillac and have them diagnose it.

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    Re: Code E49 Air Injection System Fault

    There should be a whole chapter in the FSM on how it works and the reason(s) it will throw code(s).

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    Re: Code E49 Air Injection System Fault

    Awesome I cant wait to get mine, wonder how long it will take me to read all those pages ha.

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    Re: Code E49 Air Injection System Fault

    Ok I checked the diverter valve at warm idle and I didn't feel any air coming out the bottom nipple that routes to the cat. I've read that you can't buy a new one so my only hope is to find one in a junkyard. If I can't find one can I plug the line going to the cat without adverse effects? Or I was thinking maybe I can route the air pump directly to the cat?

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    Re: Code E49 Air Injection System Fault

    On my 85 the plastic valve unit is actually two valves, first a bypass valve that will direct air to the intake in some limited conditions, and then the main valve that directs air to different parts of the exhaust (when the bypass valve has not been activated). There are two solenoids that control these two valves.

    From there on you have to monitor individual circuits with a test light to see if the signals from the ECM are getting to the solenoids, and then see if the valves are responding. Furthermore my 85 doesn't seem to use an E49 code so I can't track it down from that side either. My suspicion is that you need to replace the solenoids and/or the valves. You might call the dealership and ask if they have any, or if a part number is available then check http://www.vpartsinc.com/ to see if they have any, otherwise it's junkyard time. Really, read the material in the FSM and take your time, it's not terribly complicated.

    You might also be able to fake it with a resistor from Radio Shack in the plug, and then delete the whole valve assembly. FWIW, I had the pump seize and break the belt on a long road trip once, that was a magnificent pain in the butt. The whole purpose of the thing is to help burn off excess hydrocarbons by pumping oxygen into the hot exhaust. Literally, they could not pass the emissions standards, so they dump oxygen to burn the bad gasses. About the only thing you need to worry about is closing off the tubes so they don't let unmetered, unfiltered outside air into places you don't want it (close off the cat, close off the exhaust tubes, etc), and faking out your computer.

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    Re: Code E49 Air Injection System Fault

    Quote Originally Posted by ehall View Post
    On my 85 the plastic valve unit is actually two valves, first a bypass valve that will direct air to the intake in some limited conditions, and then the main valve that directs air to different parts of the exhaust (when the bypass valve has not been activated). There are two solenoids that control these two valves.

    From there on you have to monitor individual circuits with a test light to see if the signals from the ECM are getting to the solenoids, and then see if the valves are responding. Furthermore my 85 doesn't seem to use an E49 code so I can't track it down from that side either. My suspicion is that you need to replace the solenoids and/or the valves. You might call the dealership and ask if they have any, or if a part number is available then check http://www.vpartsinc.com/ to see if they have any, otherwise it's junkyard time. Really, read the material in the FSM and take your time, it's not terribly complicated.

    You might also be able to fake it with a resistor from Radio Shack in the plug, and then delete the whole valve assembly. FWIW, I had the pump seize and break the belt on a long road trip once, that was a magnificent pain in the butt. The whole purpose of the thing is to help burn off excess hydrocarbons by pumping oxygen into the hot exhaust. Literally, they could not pass the emissions standards, so they dump oxygen to burn the bad gasses. About the only thing you need to worry about is closing off the tubes so they don't let unmetered, unfiltered outside air into places you don't want it (close off the cat, close off the exhaust tubes, etc), and faking out your computer.
    I should have my FSM by mid week...it should clear up everything. In the meantime before I read your post Ive been watching and testing things based on all the info I've gathered. I monitored my results on the diverter valve and air is being forced to both the air cleaner and front exhaust manifold but not to the catalytic converter. Two test runs...first plugged front exhaust manifold, removed check valve and capped the hose coming from the diverter. Drove for about a half hr and mpgs were up around 2-3 in the city. Code and ses light came on when I was almost home. 2nd test was unplugging the hose coming from the diverter that I originally plugged so the air has a place to go. Idle and mpgs seemed to be even better. Throttle response even felt better from a standstill and no ses light yet.

    Went to home depot to get the right size plug for the cat hose. That will be my 3rd test.

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    Re: Code E49 Air Injection System Fault

    Quote Originally Posted by Cristofo View Post
    Ok I checked the diverter valve at warm idle and I didn't feel any air coming out the bottom nipple that routes to the cat. I've read that you can't buy a new one so my only hope is to find one in a junkyard. If I can't find one can I plug the line going to the cat without adverse effects? Or I was thinking maybe I can route the air pump directly to the cat?
    good, you just found the problem. When warm, the diverter valve should switch from the manifold to the cat. The fact that you don't have air coming from both means the diaphragms are probably in good shape. That means either the solenoids aren't working or there is no vacuum supply to pull the diaphragms.

    If you want the light to go out, the only way to do it is to fix the problem. There is NO way to trick the PCM. It relies on O2 sensor data (front bank) to monitor AIR system operation. The leads to the diverter valve are only two wire: one hot, one ground for solenoid control. There is no "signal" wire to modify that monitors diverter valve operation directly, nor does the PCM monitor the ground.

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    Re: Code E49 Air Injection System Fault

    Quote Originally Posted by drewsdeville View Post
    There is NO way to trick the PCM. It relies on O2 sensor data (front bank) to monitor AIR system operation. The leads to the diverter valve are only two wire: one hot, one ground for solenoid control. There is no "signal" wire to modify that monitors diverter valve operation directly, nor does the PCM monitor the ground.
    Interesting. Like I said, my 85 FSM does not list E49 and does not describe its cause or how to diagnose it (obviously). The only diagnostic it lists is to check ohms resistance on the solenoid, so my assumption was that the ECM was using the same test.

    When the air pump blew up I drove around for a while with a short bypass belt, and I don't remember either of the Service lights illuminating. Presumably this means that my exhaust is not monitored either. Good news for me if so.

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    Re: Code E49 Air Injection System Fault

    You can cap everything and remove the valve if you want. You can even take it one step further by removing the air pump pulley(three 10mm bolts), and running a belt for a '91 deville which did not have an air pump or stupid diverter valve. The '91 belt will fit perfectly and pass right by the air pump as long as the pulley is out of the way. Yay for free horsep0werz!

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    Re: Code E49 Air Injection System Fault

    ^^^ That is another option, if you can live with the light on. If you want the light out, you'll have to fix it. Completely up to you, chris.

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