[Brandon Meats]

Have had a nuisance problem with P0410 in my Deville. Replaced the original air pump with a New Delco one with the updated style intake hose. Lasted a couple months then the code came back. Warrantied the pump with Rock Auto and replaced a second time. When I removed the original and first replacement pumps, I noticed a decent amount of water in the filler tube and cover for the pump. Decided to mess with it again today and took the pump cover off again, no surprise it had water in it. This time I did something different though by starting the car with the actual pump motor and I take hole exposed. I didn't hear the vacuum sound like I used to and heard more of what sounded like an exhaust leak plus I actually saw and smelled exhaust fumes coming out of the pump. The water that dripped on my shirt had a slightly oily and exhausty smell to it. Once the car went through its warmup cycle, the pump stopped and the noise went away. Not knowing much about how this system works, I'm going to assume that something is not working properly and allowing exhaust to come back into the fresh air intake which may be bringing exhaust condensation along with it and over time filling the intake tract making it appear as though it's ingesting water. My assumption is that it possibly has a bad diverter valve or valves. Does anyone know how to diagnose the valves as possibly being bad? Figure I should fix that problem before tossing another $200 pump in the car so it doesn't fail again. I only get the one P0410 code and no others under the PCM heading on the in dash diagnostics. Thanks guys, look forward to your help.

 

[MoistCabbage]

Yeah, one or more of the check valves are probably bad. The first check would be to inspect all of the vacuum lines involved. Remove the engine cover and start at the check valves. Work back from there.

If the lines are fine, apply vacuum to the check valves and see if it holds.

 

[Brandon Meats]

Took a quick look at it today. I removed the engine cover and started checking what I know how to check. Pulled the vacuum line off of each of the valves and applied manual vacuum to each valve and both held vacuum. I started the engine and during the initial warmup when the pump would run I checked the vacuum at the line that attaches to each of the valves and noticed no vacuum. Went upstream to where the lines attach to the orange colored electric vacuum switch and noticed no vacuum at the switch. Next I pulled the vacuum line off that goes from the switch to the throttle body where it gets its source of vacuum and there was vacuum on that side of the switch. I don't know if the vacuum is supposed to be applied during that initial startup or after that cycle. I shut the engine off, waited a little bit and started the engine again checking vacuum on the side of the switch that goes to either valve. I found no vacuum from initial startup for about 1-1.5 minutes. I may assume that the switch may be bad? Seems like a place to start because it's inexpensive to replace that component and either way I feel the pump may need to be replaced again because I can not get it to turn on with the scan tool like I could before. Like I said in the first post I probably emptied a pint of water out of the pump last night. Could replace the switch and see if that changes the vacuum during startup so I may be able to eliminate that before another pump replacement. Any thoughts on how to check the other components without the air pump functioning? Just to reiterate, upon initial startup last night I heard and saw exhaust coming out of the bottom of the air pump with the lower cover removed for about that first 30 seconds, then it stopped.

 

[Submariner409]

AIR can be a bear to troubleshoot because it does not run on every startup - and it sometimes runs longer than other times, and those times are dictated by time since last start and outside temperature.

If you saw engine exhaust coming out of the AIR pump cover, you have one or both check valve problems OR the system was functioning to allow air FROM the pump TO the manifolds - but no pump = no air. The pump itself is a blower - air/gas can easily flow through it either way when it's not running.

Lotsa water = bad blower.

 

[MoistCabbage]

Yeah, if there's no vacuum, and the exhaust is back flowing through the AIR system hoses, one or both of the check valves are stuck open.

 

[Brandon Meats]

This probably also explains why I smell exhaust inside the cabin from time to time. It pumps it back through the system and out of the intake tube behind the airbox, and most likely right into my partially open window. Had it on the hoist at my buddy's shop and could not find one exhaust leak in the system. Probably also explains why when I get on it hard entering a highway I smell sulfur inside, it's pumping back through that air pump and into the window as well. The strong sulfur smell is probably another issue in itself, but one thing at at time. Lol.

 

[MoistCabbage]

The sulfur smell is very likely normal. That exhaust flow is coming from before the converter, it should stink :yup: .

 

[Brandon Meats]

Just an update, I know it's been a bit but thought I'd check in. Had a coil pack go out so I changed both of them along with the boots and plugs. Rear check valve had to come off for the job so I replaced that with a new Delco unit and gasket. The new one came with the pipe, bracket and vacuum switch so all is new. Fired the car up and could hear the exhaust coming out of the air pump intake yet. I ordered the front check valve as well so that when I replace the air pump all should be good. The one thing I'm wondering is that if I fire the car up I hear the exhaust, if I unhook the vacuum line from either diverter valve, independently or simultaneously, the exhaust sound goes away. Does that pump just force that much air that it overpowers the exhaust backflow, or is there another possible culprit here?

 

[Submariner409]

The pump starts and then the check valves open depending on ambient temperature, coolant temperature, and time since last start. The centrifugal pump puts out enough pressure to push fresh air into the exhaust manifolds at idle or low - low load engine speeds - extremely low exhaust system backpressure. The pump normally only runs for a few seconds.

No pump run, check valves open (commanded open by the system) and you get exhaust out the pump intake. Much of this backflow and the entire system - gas and air piping - burns out and clogs up. Mucho dinero to fix then.