Macan Secondary Air Injection check valve

[Sandpebble]

My SAI pump failed. Got the P0411 error, did some trouble shooting. It appears the original pump had some kind of air filter material in the inlet. This appears to have decomposed, got down into the rotors, which then broke off some of the rotor teeth. I disconnected the air lines and vacuumed them out, got at least one piece of broken tooth that otherwise would have gotten to the exhaust valves.

 

I replaced the original pump, and the new blower seems to work just fine.

After restarting, I got the P0411 again. I re-checked my work, and found I did not reattach the hoses properly, so air was escaping. Once those were firmly attached, I watched the blower flow rates as I started the engine. Bank 1 had a higher flow rate than Bank 2. The only error code to appear was P0492, which is low flow on Bank 2. I pulled the hoses completely out found a couple more of the broken rotor teeth in the Bank 2 hose. Put it all back together and started the engine again. Still getting low flow Bank 2.

I fear that broken teeth may have gotten into the check valve on the left side, interfering with its operation. I haven't figured out yet how to get the valve off, but that is this project's next phase.

 

Does anybody have any experience or advice on removing those check valves?

[Sandpebble]

A further update:

I began to take the Bank 2 (left side) valve off. It is nearly impossible to get to the bolts. I got one out, and had most of the second out, when I wised up. I am certain if I got the second bolt out, I would NEVER be able to get it back in, short of pulling the engine. There is no room to get in the two fingers that would be necessary to start the bolt in.

So I checked a couple of things. I connected the blower hose while the valve was loose, and blew into it to see if it was functioning. Then tried the right side valve. The right side had much more resistance than the left, somewhat confirming my theory. BUT, I also tried to suck on the right side valve, and it was easy to draw in hydrocarbon smelling vapor. In other words, the check valve wasn't "checking". I put my inspection camera into the valve, and could see two of the broken-off rotor teeth stuck in the valve sealing surface. That explains (I think) why Bank 1 had double the flow rate of Bank 2. It was stuck open.

The good news in this is that the Bank 1 mounting bolts are far more accessible, and I was able to remove the valve without difficulty. Rather than just trying to pluck those teeth out and re-use it, I went ahead and ordered a new one.

The project continues....

Edited July 17 by Sandpebble

[Sandpebble]

Fixed! I replaced the right-side (Bank 1) check valve and reconnected the hoses. Watched the live data as I started the car. The two banks were roughly equal in flow, with both topping 11 kg/hr. No Codes!

 

Total cost was about $300. That's $150 (delivered) for a replacement blower, and $150 (delivered) for a check valve.

 

Should anybody else ever need to remove a check valve (and I hope you don't), the tool that makes it possible is an E10 Ratcheting Box-End E-Star Wrench. I got mine from Amazon for $13.