Weird parts Questions

Ok guys I have the following questions of what these parts are and what they do.


1- Looks like a round pump mounted on the driver side fender well, down low, has brake lines coming in and out of it. Is this the ABS pump?

2- On the front of the engine on the exhaust side, looks like a EGR valve or something and has a hose coming out of it and runs down below into the RF bumper well area. ?? EGR? Where does the hose run to? Very interested in what this is.

EDIT: Looks like items #2 is the air pump system. Guessing the air pump itself is down in the bumper wheel well area and the hose come up to a check valve of some sorts. What a crock. Please tell me you can disconnect the air pump and put a block-off plate on manifold? Not to mention the 10' of vacuum hose running to the damn thing.

1. I suspect you're correct. The diagram suggests it mounts to the left side of the compartment.

2. Sounds like the secondary air pump connection.

Buy the Bentley E39 service manual.

^ I have the manual. It rocks. but sifting through some stuff is more "social" on here. I really hope I can delete the seondary air pump system w/out getting a check engine light of some sorts.

You can not delete the secondary air system. Some will say there is a "Sim" made for this purpose. You will be far better off to give in and keep it functional. it isn't that expensive. Most all cars (Audis, VWs, M-B, etc.) have a version of the secondary air system just for emission purposes. See what is wrong with yours before you give-up. The pierburg pump can be for an Audi and is about $107 on Amazon or nearly $300 for a BMW plus $100 valve. Want to delete it? Go for it. Read up on "SAP delete"

^mine is fine. I just hate un-needed crap under the hood. Less parts is better. But you're right... if it's not a easy thing, i'm working... leave it.

The e39 SAP delete appears to be an urban legend. Some claim to have had success with the e46 but I have yet to find an e39 that has sucessfuly completed this action. As PM, clean or replace the SAP check valve every 100K. The SAP check valve opens to allow air to be injected into the exhaust stream. Because it is part of the exhaust stream, it gets carbon deposits that can impair opening or closure. If it fails to close, hot exhaust will enter the air pump, where the moisture will condense and kill the pump. This can get expensive. My previous e39 went through 3 air pumps in 75K. My current one is still on the original at 108K. Go figure...

I believe the point of the sap is too help the cats heatup faster resulting in better emissions witt the engine still cold as well as prolonging the life of the cats. Raw fuel is the enemy of your cats. Running rich will destroy them as well as running lean. Rich will clog them, lean will cook them.
Sap delete may equal premature cat death. Dont quote me on that though

Lean is not an issue for cats. They are a catylist. They only react to what is introduced. Rich, that will deff overheat and clog them.


As for the SAP. I'm glad I educated myself and found it and all. I am worried baout the check valve though. I may take it apart and see about cleaning it. Or price a new one. The SAP blows air into the exhaust system so the unburned carbons have a Oxygen supply and a chance to further burn off. Only works when the car is cold as about 10 minutes later when your Cat is up to temp the SAP is not required.

The valve runs about $90-95

The leanness itself may not be bad but what happens is a lean engine runs hotter exhaust gases and can melt the cats.

I believe the valve is highly recommended to be replaced with the sap.

Originally Posted by FLE39

Lean is not an issue for cats. They are a catylist. They only react to what is introduced. Rich, that will deff overheat and clog them.


As for the SAP. I'm glad I educated myself and found it and all. I am worried baout the check valve though. I may take it apart and see about cleaning it. Or price a new one. The SAP blows air into the exhaust system so the unburned carbons have a Oxygen supply and a chance to further burn off. Only works when the car is cold as about 10 minutes later when your Cat is up to temp the SAP is not required.

The ECU monitors the oxygen sensor response to determine the operation of the SAP and sets a code and the CEL if it fails. I think that's why most people replace them when they fail.

I have no codes or reason to believe the SAP is bad. I'm just worried about the check valve sticking and causingmy pump to go bad. Valve <$ SAP.

Yep. That's the reason to clean or replace the valve.

Also, that small vacuum line that attaches to the valve goes to an electric valve mounted just below the intake manifold just in front of the firewall. The other end of the hard plastic line that runs on the right side of the valve cover is attached to the electric valve with another short piece of hose. Then there is another piece of hose that attaches the input side of the electric valve to a one-way valve and a piece of hose from there to a vacuum port on the intake manifold. These hoses are hard to reach and they're not exposed to the heat of the exhaust like the hose that attaches the hard plastic line to the SAP valve, so they're probably OK. But if you're bored sometime, you might replace those hoses, too.

BTW, I can confirm that the DSC compressor (ABS pump) is located on the inside of the left fender just below and behind the water valve on my 2001 530i. That's probably the first part you're were asking about, just as you thought.