2002QC

Initially the hose from the pump to the combi was busted so I made one.

Now, on cold starts the engine idles at 1250rpms like it should, for around 5 minutes, then drops to 750 - 800 once warmed up.

I checked the rivets on the pump, and everything looks ok. Haven't tested it with the vagcom because it's obviously pushing air.

I have tested the combi by taking it off and blowing as hard as I could onto the inlet, and no air passed through.

But I still have p0411 incorrect flow.

So what should I order? I don't know whether to buy a new n112, buy a new hose, or bust out what looks to be still decent rivets on the pump. The steady rpm rate seems to me to indicate that my makeshift hose is working, and the system functions on every cold start without fail. But I still have the code (been cleared multiple times).

I am aware that I have the option of deleting the system, but that's not something I'm particularly interested in at the moment.

 

p0411 has been my bain of existance for the past 4 months.

1. pulled SAI and replaced revits with screws. can you see the top revits with pulling it?..I couldn't. continued p0411.
2. pulled SAI, retightened all screws as it appeared some were not even. replaced small vacuum hose to kombi. P0411 gone...but only for 1 week
3. pulled combi. cleaned, tested with vacuum pump, worked fine. Air blowing thru hose as expected. But, continued po411.
3. pulled SAI and removed hose from pump to kombi valve. 4 cracks/breaks in the hose. repaired with shrink wrap. Success. VAG-COM showed all was normal, all tests OK. Woo Hoo! P0411 gone.

Fast foreward to last thrusday....CEL returned three weeks later. I have not checked it with VAG-COM yet but I think it's the hose as it was really in bad shape and I'd not be surprised if there are additional cracks/breaks. So, I'll be getting a new OEM hose and see what happens next.

I'd bet you do have at least one or two revits in need of repair. Also check the small vacuum hose going into the combi valve. Mine was cracked as noted above. It may need to be replaced too. Otherwise, it may be your home-made hose from the pump to the combi...if that seal is not tight enough, you could still get the code. I believe the combi is somehow calibrated for an exact amount of air from the pump...if it is getting too little it may throw the code. In my case, the pump was blowing fine but I had leaks due to the cracks, so the combi was getting air but not enough.

if you haven't enjoyed the fun of pulling the sai pump, be ready for a real PITA. Here's a good DIY. After pulling mine 3 times, I found this was the easiest although perhaps the longest too. Mike has additional pictures and discussion in his fotki link as indicated in the QW thread.

http://forums.quattroworld.com/tt/msgs/111620.phtml

good luck,

cheers.