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7 Series - E65 / E66 (2002 - 2008)
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  #1  
Old 04-21-2011, 10:03 AM
Got_boost? Got_boost? is offline
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Loosing my head, looking to get help from community. Secondary air flow

whats up people. i ran into some issues with my 2004 BMW 745li and just cant seem to figure it out. i know there is some smart people out here that could help me out.

to start off, i got a check engine light, and it read P0491. So i immediately did some research, and came up with insufficient secondary air flow bank one. then i did more research and it said that it should be the passenger side bank, either the valve or the hose with the y connection under the intake manifold. So at cold starts, the pump starts buzzing and then it shuts off in like 30 seconds after cold start. so i determined that pump was good. I then ordered a new valve and a new y hose so i can tackle the problem. i replaced both, and made sure everything is plugged in and good n tight. torqued the manifold and connected everything back.

I then started the car and the code was off for a lil while but it came back on with the same code. so im lost. I dont know if the drivers side valve could cause this, but i know that bank 1 is passenger side. If anyone has any imput to shed, please do so. I read every single post on this on bimmerfest and still couldnt come up with something new.

I also have another question, if one of you 2004 745li owners could do me a huge favor. i saw in some posts if you have problems with vacuum lines, or maybe the ccvv, it can possibly throw this code. so i realized on my car that i have the pressure regulating valve on the valve cover thats possibly missing a hose to connect to the nipple. and then i saw on real oem, that i also need to have a pressure regulating valve on the passenger side of the engine valve cover, right behind the oil cap. now if someone could clarify this for me, it would be greatly appreciated.

heres the first pic, with the valve circled in red.



and the second pic is of the passenger side and it looks to me like it needs to have the same valve, right next to the oil cap.



and here is from real oem a pic, i put my vin number, and this is what they gave me.




any helpful input is really appreciated, i need to pass emissions so please help a fellow brotha out!
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  #2  
Old 04-21-2011, 02:37 PM
Got_boost? Got_boost? is offline
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  #3  
Old 04-21-2011, 07:19 PM
Keif Keif is online now
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The state of the CCVs shouldn't impact secondary air flow, only crankcase pressure, intake pressure, and oil/air separation. The secondary air pump pushes fresh air directly into the exhaust manifold / post-combustion area in the head to continue burn during cold start (to improve emissions, I believe) -- so that system is entirely independent of stuff related to the CCVs (...to help you eliminate items).

You replaced both the hose and check valve and still had the issue? Have you pulled off the connector for that hose at the front of the engine and tested the air pump that way? I think a while back someone ran power straight to the pump to test it (look through some threads about the air pump); I can look up the wiring diagram if you need it. Just because the pump is buzzing doesn't necessarily mean it's actually pumping anything, and maybe the bank 2 side check valve just isn't as stiff or something (i.e. easier to push air through and so is not faulting).
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Last edited by Keif; 04-21-2011 at 07:28 PM.
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  #4  
Old 04-21-2011, 08:29 PM
Got_boost? Got_boost? is offline
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Quote:
Originally Posted by Keif View Post
The state of the CCVs shouldn't impact secondary air flow, only crankcase pressure, intake pressure, and oil/air separation. The secondary air pump pushes fresh air directly into the exhaust manifold / post-combustion area in the head to continue burn during cold start (to improve emissions, I believe) -- so that system is entirely independent of stuff related to the CCVs (...to help you eliminate items).

You replaced both the hose and check valve and still had the issue? Have you pulled off the connector for that hose at the front of the engine and tested the air pump that way? I think a while back someone ran power straight to the pump to test it (look through some threads about the air pump); I can look up the wiring diagram if you need it. Just because the pump is buzzing doesn't necessarily mean it's actually pumping anything, and maybe the bank 2 side check valve just isn't as stiff or something (i.e. easier to push air through and so is not faulting).
I will unplug the connector and test the pump tmrw. I have not tried that. I had someone replace the passenger side valve cover. So i was wondering if they put the wrong one on, because there should be that pressure regulating vavle right next to the oil cap,(as you can see in the pic from real oem) but my car doesnt have one (as you can see in the pics up there). So im just trying to see if other 2004 bmw 745li's have that, or if it looks like mine, because i would think without that pressure regulating valve, it is unable to regulate ccv pressure in the head on the left(passenger side)?
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  #5  
Old 04-21-2011, 09:07 PM
Got_boost? Got_boost? is offline
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also shown in this link that there is two crank case vent valves.. but mine has only one on the right side of engine.. im so confused....

http://www.raiseitup.com/bmw_repair1/
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  #6  
Old 04-23-2011, 09:38 AM
Got_boost? Got_boost? is offline
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  #7  
Old 04-23-2011, 10:41 PM
mrringtone mrringtone is offline
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I just had this same issue corrected at BMW. It was my diverter valves and supply line. If you can get your hands on a TIS like I did just do it your self. I paid BMW $1,308.00 to fix this issue and tell me why my check engine light back on again throwing the same code! I will be at the dealership next Wednesday to have this resolved.
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  #8  
Old 06-03-2011, 09:05 AM
adboles adboles is offline
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mrringtone, did the dealer tell you when you went back that your heads had carbon build-up?
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  #9  
Old 06-03-2011, 09:36 AM
ClaussenE38 ClaussenE38 is offline
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ASE / MECP MASTER LEVEL

PVC or Ccv help keeps you from getting oil leaks, in the simple explanation. They relieve pressure from oil cover gaskets, oil pan, ect. Absolutely nothing to do with a check engine light.
You have a bad sensor that controls air fuel mixture or a vacuum leak. I would find the specifications on those sensors, check their values with ohm meter, and eliminate possibilities. A scan tool with live data should pick this issue up immediately. Mass air flow sensor is a good one to start with. Also, an e-38 model much less complicated : )
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  #10  
Old 06-03-2011, 11:01 AM
joej85 joej85 is offline
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The secondary airflow system exists to heat up the catalytic converters under cold start conditions so they start working faster. The system only activates when the engine is started when cold. As you noted, the pump runs for about 30 seconds and doesn't come on again until the car is cold started again. Based on how my E46 operates, I think "cold" is defined by a certain ambient temperature, so the system may not even operate at all if the ambient temperatures are above a certain level.

On the 745, the pump runs and the air pressure of the pump causes the valves to open up. Air from the pump then flows through the valves, into the exhaust manifolds and on into the catalytic converters where the extra air causes the extra fuel in the system to burn which in turn heats up the converters. The extra air flowing in the exhaust mainfolds is sensed by the o2 sensors. If the sensors don't see a lean condition from the extra air, codes get set in the computer for improper secondary air flow. Your passenger side O2 sensors aren't seeing the lean condition, so the low flow code is getting set.

The sad thing is the car will work perfectly fine without the secondary air system. The cat converters would just take a little longer to heat up.....

If you have replaced the offending valve and hose, and you have confirmed that the pump is working properly, then it is likely that the Air Intake Tube that goes between the valve and exhaust manifold (#9 or #10 from the picture below) is clogged with carbon. If you have DIS, you can activate the pump to test it and run step by step diagnostics on the secondary airflow system.

If you can get a piece of the right size hose and connect it to the input of the valve, you should be able to blow into it and see if it opens. If it is working properly, you should be able to blow air freely through the valve. Try both sides and see if one works and one doesn't.

If you find one passes air and one doesn't, the Air Intake Tube is probably clogged. I would remove the valve on the clogged side and then start the car to see if any exhaust comes out of the air intake tube. If one of the tubes is clogged, you will probably have to remove it to see if you can clear the clog. Its possible that a passage in the exhaust manifold is clogged too.

I suppose its also possible that the intake tube to the air pump is blocked or partially blocked too, so make sure and check that too.
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Last edited by joej85; 06-03-2011 at 11:20 AM.
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  #11  
Old 06-03-2011, 11:44 AM
adboles adboles is offline
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joej85, thanks for the detailed help! My dealer supposedly replaced all these hoses, valves etc, and came up with a final determination that the head were plugged with carbon build-up. They even reccomended I don't fix the car because of the cost to do so. I started using ethanol free gas, and I have changed the oil twice in the past 2,000 miles. On the first oil change, I added some Sea foam to the oil, reccomended amount for an engine flush, and ran the car until the oil got much darker, about 500 miles, then made the chang. I also ran 3 can of Lucas gas treatment through the system on every other tank intervals. Prior to doing this, I had a low rpm intermittent miss, and now the miss is gone completely. I may have had a dirty fuel injector, but I hope the efforts are beginning to clean out some of the carbon build-up. I will be getting the SEL soon light re-set next week to see if its fixed. The last time I had the OBD codes read the only ones that came up are the 0491 and 0492. Do you have any idea if there is a specification for CFM readings on the secondary air pump. After all, mine has 155,000 miles on it and its an 02 model so maybe its tired! By the way, before the dealer replaced all the secondary hoses, valves etc, I had smoke after long idles. That seems to be fixed now. I haven't seen any smoke for some time.
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  #12  
Old 06-03-2011, 12:31 PM
joej85 joej85 is offline
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I am sure the pump has a flow spec, but I have no idea what it is. Its sort of like a vacuum cleaner operating in reverse, so I would expect quite a bit of airflow.

If the intake hose to the pump is blocked or partially blocked, the airflow would be restricted into the pump, so that would cause low airflow out of the pump. If you are getting codes for both sides, that could easily be the problem.
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  #13  
Old 06-03-2011, 01:48 PM
adboles adboles is offline
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joej85, I was on an errand after my last post and decided to swing by my indy shop and ask him to check my codes and reset the lights. This time, I only got one code 0491! I am pretty sure that is the passenger side.. This is the first time since this all started that I didn't get both codes! I plan to get an idea about air flow on that pump, not just the fact that it comes on. I really appreciat your help, please keep any fresh ideas coming and I'll post any additional news.
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  #14  
Old 06-03-2011, 07:20 PM
1172scorp 1172scorp is offline
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I've been having the same problem with the secondary air flow. I was recieving both codes (p0491+2) then just p0492. I did the pump test by unpluging the hose and starting the car. I felt the air coming from, so I'm assuming that the pump is good. Don't want to take it to the shop for something I can fix myself. Right now I have both codes again. Could it be the Air Pump Control Valves?
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  #15  
Old 06-04-2011, 10:29 AM
adboles adboles is offline
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1172 scorp, It might be the valves but I'm pretty sure they have a differnt code, not positive, but I would check for separate codes before going to the shop. I'm thinking about checking the air flow volume myself. Was your pump moving a lot of air, or just a little? I'm wodering if after 150,00 miles the pump weakens, like a bilge blower does on an older boat. I had both codes 0491 and 0492 until yesterday. Now I'm just getting 0491 which is passenger side, bank one. I've reset the light and counting the cold starts before it comes back on.
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  #16  
Old 06-04-2011, 10:36 AM
1172scorp 1172scorp is offline
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Yeah those are the only codes that I'm getting right now. I've trying to get to the back of the intake manifold to see if the hoses were loose but it's hard to see. The pump was blowing a lot of air. I wonder if it could be the pump only working correctly some of the time. The light doesn't come on right away. It comes on after I drive for about five minutes.
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Last edited by 1172scorp; 06-04-2011 at 10:39 AM.
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  #17  
Old 06-04-2011, 10:51 AM
adboles adboles is offline
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I have been told that it takes at least two cold start failures to get the codes. Mine is a delayed reaction also, about three miles or 5 minutes too. Looks like we have the same car, mine is an o2 model, we bought it new and have been through all the updates, recalls etc. Really disappointed this problem is so difficult and expensive to fix.
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  #18  
Old 06-05-2011, 06:05 PM
tugman3461 tugman3461 is offline
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Hey Hey

I just so happen to be working on the same problem accept mine is bank two, I found the bank one valve stuck open so the air is taking the path of lest resistance. I have been here before so i am changing both valves cause idon't want to take intake off agian. good luck with your dealer, thats why I do my own work (pics to follow}
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  #19  
Old 06-06-2011, 12:22 PM
adboles adboles is offline
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tugman 3461, I'm looking forward to those pictures. My sel light came back on after only two cold starts. I'm assuming its still just bank one code 0491. I don't know why 0492, bank two, isn't defaulting or what exactly fixed it. Dealer said they replaced both valves and I understand there are separate codes for those. Is that correct?
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Old 06-06-2011, 07:20 PM
tugman3461 tugman3461 is offline
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well well

I just purchased a borescope to take a look down my tubes it will be a couple of days to get it but it has the ability to to take stills and video can't wait to post the those pics. I'm thinking about opening my shop for customers agian, any one in my area interested in giving me some buisness.
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  #21  
Old 06-06-2011, 07:24 PM
1172scorp 1172scorp is offline
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I'll be waiting to see what you come up with too.
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  #22  
Old 06-08-2011, 10:13 AM
mrringtone mrringtone is offline
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@adboles - BMW did tell me I had carbon build up. The odd part is my 2002 745i has 78k on it. I think it was BS
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  #23  
Old 06-08-2011, 09:41 PM
teejaylentz teejaylentz is offline
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Quote:
Originally Posted by Got_boost? View Post
I will unplug the connector and test the pump tmrw. I have not tried that. I had someone replace the passenger side valve cover. So i was wondering if they put the wrong one on, because there should be that pressure regulating vavle right next to the oil cap,(as you can see in the pic from real oem) but my car doesnt have one (as you can see in the pics up there). So im just trying to see if other 2004 bmw 745li's have that, or if it looks like mine, because i would think without that pressure regulating valve, it is unable to regulate ccv pressure in the head on the left(passenger side)?
That's interesting that the passenger side doesn't appear to have the pressure regulating valve... I wonder if this is a new "improved' design?
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  #24  
Old 06-09-2011, 03:58 AM
1172scorp 1172scorp is offline
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Quote:
Originally Posted by teejaylentz View Post
That's interesting that the passenger side doesn't appear to have the pressure regulating valve... I wonder if this is a new "improved' design?
It does have one. That's it just to right of where you put your oil in. They just move it a little.
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  #25  
Old 09-28-2011, 09:28 AM
vaed2010 vaed2010 is offline
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Has anyone found the solution to this problem? I have error codes 0490, 0491 and 0492.
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