P0491/2b70... the saga continues

[bmwlover0725]

I've been dealing with this issue since I purchased this car. I have a bank 1 insufficient flow. I'll make this as easy as possible - here is what I've done...

1. Swapped O2 sensors (did a reading and they're both fine anyway)
2. Cleaned and tested bank 1 valve. It was caked with carbon, but it is operating just fine now.
3. Scraped out the entry port on the engine for bank 1 and put it back together with a new gasket.

I'm sure that anything is possible, but I thought that these weren't plagued with the issues that the E39 M5's suffered from with ports clogging.

Does the sensor on the hose going to the pump from the intake affect the reading? I'm sure it does, but it would be a failure on both banks, wouldn't it? Also, the pump itself wouldn't make one bank bad without having something to do to the valve too as far as I can tell. The pump alone would throw a code for both banks and I'd assume the pump itself would have a code as well.

If I put my hand on the hose going to the pump, should it have a very hard suction? I can do that later and see what it is like once the car cools down enough.

[8600RPM]

Strange. May want to just by a cylinder head used

[Dave07997S]

P0491 is secondary airpump I believe...PM Mike Benvo with BPM he will steer you in the right direction. Either its an airpump going bad or a disconnected vacuum line.

[anom3]

OP... Sorry to hijack your post but:

When you cleaned your ERG valve(s?)... How did you get to it?

Did you drop the exhaust? Or were you able to get to it fairly easily?

BTW : I have cold start disabled, but: A few weeks ago I did a plug swap. When putting everything back together I forgot to plug in the sensor on the hose running from the air intake to the 2ndary air pump. No code was thrown, nothing. Car ran just fine. I noticed this 2 weeks later when doing something else. As mentioned, my cold start is disabled via a tune, so maybe this is why no code came up.

[bmwlover0725]

Originally Posted by anom3

OP... Sorry to hijack your post but:

When you cleaned your ERG valve(s?)... How did you get to it?

Did you drop the exhaust? Or were you able to get to it fairly easily?

BTW : I have cold start disabled, but: A few weeks ago I did a plug swap. When putting everything back together I forgot to plug in the sensor on the hose running from the air intake to the 2ndary air pump. No code was thrown, nothing. Car ran just fine. I noticed this 2 weeks later when doing something else. As mentioned, my cold start is disabled via a tune, so maybe this is why no code came up.

If you're talking about the house running TO the pump rather than from the pump to the valves, you should be able to get it just by reaching back. Have small hands so I can remove that hose and even the one going to the valve without any tools at all. To remove the valves, I remove the intake manifold and basically climbed in the engine bay. I've worked on these cars for years and having small hands helps because you don't need to remove half of the things that BMW recommends doing.