BMW Repair: secondary air system, bank one, obd ii, air passages

Question
Evan, I have a 2001 x-5 with a v-8 4.4i. The fauty code is 81, As same as OBD II p0491. It is about secondary air system that works only during a cold start. And it shows only bank one that has problems. I have checked the air pump, check valve, vacumm lines,and elec. valve. And they all seem to work just fine. Acording to bmw bulleton, if all air supply system componants are ok, the possibility is the clog of the air passages in the engine head. I took a mecanics' suggetion to open up the check valve and poured  some Sea Form cleaner in the air supply pipe. The tail pipes would release some smoke and the next day, the check engine lite would go away. Unfortunately, it would come back one or two days later. BMW blames on the use of gas that does not have adquate detergin. Nobody would use any other gas except for premium. I just don't want to accept the possibility of a clogged up engine head. If it is really the cause, is there any alternatives to clean them up besides pulling out the head to clean it up? I mainly drive it on highways, and have oil changes more often than what the lite tells. The vihecle starts and runs just fine, but the yellow lite is annoying. Oh, it's got 86000 miles on it. Any ideas would be highly appreciated. Thanks...  

Answer
PJ, make sure the vacuum line to the secondary air valve is good and not cracked or broken. (I know you said you checked it) If you have the version with out the vacuum hose then the valve is just opened by air pressure from the pump. The clogged Secondary air passages in the head is a possiblity. The aluminum pipe that the secondary air valve sits on is the crossover tube. Make sure it is not loose. Remove it and check the O-rings. The passage where this tube bolts up is the main passage that runs the length of the head. There are smaller offshutes (four, one for each set of exhaust valves) that branch off from the main Passage. It has been my experience with this issue that the main passage cloggs up and not the smaller offshutes. We find this after removing the cylinder head and removing the exhaust valves. This is the only way to clean the smaller offshute branches because they are parallel to the valve guide and you can't get to them. My suggestion is this: Remove the Exhaust from the exhaust manifolds, remove the crossover air tube and anything in the way of that passage. Use a blow gun with shop air and blow into the passage while someone feels the volume of air comming out the exhaust collector. Check both sides and compare the two. Second cut a coat hanger or a stiff but flexible piece of wire and measure how far you cans stick it in the passage in the head. If it doesn't go the length of the cylinder head then you know it is clogged. BMW has a kit to clean this passage. It is basically a flexible shaft and a rifle/shotgun cleaning tip (Brass/copper bristle). With an electric drill use the shaft to ream out the hole. We end up using three brushes per side on severe cases. At the other end of the passage it a steel plug that can be removed and replaced with new to make sure you got all the way through. The Service bulletin is 11 05 04 ask you dealership service writer for a copy. The full cleaning kit ($500.00) is part #        99 00 0 006 668 includes the diagnostic tool. The brass brushes ($47.25 each) come in a set of 3 and I would recommend ordering two is 82 11 0 416 755 . All the part numbers are in the bulletin. There are Freeze plugs($2.35 set) that the bulletin says you need 3 kits part# 11 12 1 736 330. Get a copy of the bulletin and look at it. Decide from there what you want to do. If this helps please fill out a follow up survey. Thanks.
-Evan