Thank you for the answers.

About the secondary air pump. It is true that it has errors and don't work correctly (the pump doesn't have grinding noise, but I can hear it in the car and very little while listening it while being in front of the car outside.) But here I still don't get why it would cause a misfire. The pump is on for 30-90 seconds and after it has heated up the sensors and cats, the car can enter closed loop. I'm getting rough running from the first second after starting the car and misfires come quickly after that.

For me it seems like the car is for whatever reason starting in "closed loop" while the engine temp is below 3-4 degrees and then can't control itself anymore.

"A cold car starts in “open loop,” a startup sequence that runs more or less based on memory, rather than sensor input. After the car is warm and the thermostats start functioning, the car can enter “closed loop,” a state where the car runs based on its sensors and less so on memory."

https://www.reddit.com/r/BMW/comment...our_n62_44_v8/

I've also read that while the engine temp is 20-60 degrees, the car will use throttle plate during the start. This leads me to think that ECU has different settings for different temperatures and it might calculate something wrong here.

Today I got a good comparison between start up behaviours depending on the temperature. I did not connect INPA this time. Yesterday the car standed 15 hours in -1 degrees. Today its standed 15 hours in 4 degrees. The start up
differences were massive. Yesterday I started the car and it was extremely rough and a misfire message popped up after a few seconds of running. I needed to restart the car several times to get it running ok. Today, however, the car had almost no rough running, no jumping revs, everything was as it should be I guess. Using my past experience I'm 99,9% sure that yesterday the valve lift was 0,3mm while starting the car and today 6mm.
This brings me to the idea that is has to be connected to the software due to the temperature differences being so little, but behaviour is very different.

Still would like to see INPA readings of valve lift from a car, that doesn't have the rough running or misfires during the start with 0 degrees engine temp.

cmyachtie
My intake is also a bit oily. I checked the CCV valves, they looked to be in very good shape and I also removed the CCV hose from the intake and saw that the inside of the intake was cover with a thin layer of oil. The hose had also very little oil in it.

One theory of mine is connected with oil. The viscosity of the oil starts to increase around 5 degrees more rapidly, maybe it has an effect on Vanos if the solenoids are not clean enough? I suppose it should give some error codes, but right now it doesn't.

http://i46.tinypic.com/124v774.gif

Some quick updates:

I removed MAF plug yesterday and started the car while it was completely cold (had been standing over 24 hours) and it was -4C outside. The car fired up really nicely, no sign of any rough running problems. Only thing was that I could smell that the car was running rich. After a minute or so I turned the car off, plugged MAF back in and fired it up again. Engine run fine.

Today car had been stationery for 12 hours in -4C cold and it started perfectly. Before starting I made a throttle adaptation (holding gas pedal for some seconds with ignition on etc) if that would have any effect, I doubt it. Again I have the feeling that today it started with 6mm valve lift because I could here the car going to closed loop after a minute or two (a small rev fluctation happens then). The engine ran fine during the cold morning, what a feeling. One possibilty is that the car hadn't cooled down with 12 hours. There was a thin layer of snow on the car that might act as a thermal isolation.

FWIW.....I don't think snow insulation is a factor, in my experience the cold start problem is totally random except for the cold ambient temps being a constant and even then not always......
I am beginning to zero in more on oil since in my case vacuum leaks have now been eliminated, I have always run with Castrol 0W30 and switched this year to 0W40 and I think my starting issues have gone worse and more frequent thus far this winter, also my mileage has gone south to the tune of 10%. Am going to experiment with an oil catch setup preventing the CCV from putting oil in the intake, there is another thread where I picked this up from. Haven't installed it yet but got all the needed parts.

Tried to attach a pic but lately this site won't accept png pics from my iPad will do later from my pc but here is the link, this is on a N62TU engine but you get the idea. Just have to cap off that lower drain not shown here.

Bimmerfest - BMW Forums - A B Able Truck's Album: Oil Consumption (CCV) fix - Picture

Btw. It's -4C out here today and will hook up INPA Before starting car today and take the valvelift reading. Keep you posted.

You have secondary air pump error codes and are not eliminating the secondary air pump as the cause? Certainly there could be another cause but your symptoms are exactly as those caused by a failing-failed secondary air pump. You have symptoms and verifying codes.

BMW Secondary Air System Fault Code Diagnosing How To DIY OBD-II | Bavarian Autosport Blog

No fault codes or stumbles at startup but posted vid of valve stroke set points at cold start here:
https://youtu.be/AArs1kr9Dak

2. mm setting

Here is the set point after warm engine has been shut off for half hour @ freezing ambient temps

https://youtu.be/Qz0qyW0ozdw
6. mm setting

The problem is that I haven't found the list of symptoms that would indicate that the secondary air pump can causes rough running. The car should run fine with or without it. Also it doesn't make sence that starting it up with 5C coolant temp everything is fine, but at 0C big problems appear. If you could link me information where it is said that SAP is causing rough running troubles around 0C I would really appreciate it.

For me the secondary air system has one job to do:
During cold start, the engine efficiency is not the best so there will be more hydrocarbonates going to the exhaust. Blowing more air to the exhaust will rise the exhaust gas temperature and help heating up oxygen sensors and catalytic converter quicker so that the car could go to closed loop where it can work more efficiently.

Having this though in mind, I don't see how secondary air could change the way engine is running while cold. Basically the secondary air will never enter the engine and doesn't participate in the cylinder filling procedure, it will enter the exhaust ports only.

Yes, I do have the codes and it is a very common problem with these engines, but it is very expensive to fix and I haven't found a reason to do that. People who are fixing it are usually from USA where the car is checked for fault codes during the yearly inspection and if they have this code, they will fail at the inspection. In europe the CEL light is not illuminated and the codes are not checked during the yearly inspection, at least in my country.

My current guess is that it is software related problem. But you never know, some have had Vanos seal issues with same symptoms too.

A secondary air system will only cause a real running situation if it is still running after the catalytic converter warm up phase has ended.

Example: The relay that powers the secondary air pump is stuck closed and the pump continues to run.

The intermediate lever test plan is not a real test plan that worked when testing these systems.

The cheapest solution would be to sell the vehicle, or always park the vehicle in a heated garage, or live with it.

Another solution would be to install a Webasto parking heater and to reverse the operation to heat the engine block instead of the cabin heater circuit.

The most expensive solution is to replace all the levers, shafts etc, and hope that it lasts for more than a year. Even when brand new, especially on X5 N62 engines, i've had to replace multiple levers year after year under parts warranty due to repeat issues.

0-30 and 0-40 have the same viscosity when cold. No reason that change in wt. range of oil has anything to do a cold start issue. Rather than experiment, I would suggest a much better plan would be to troubleshoot until you find the core problem rather than throwing parts at it to see what happens.

You came here asking for help because you haven't been able to solve the problem you are having. You don't understand why the SAP can cause your issue so you have decided it can't. You have been going on guesswork and experimentation and that isn't working. Perseverance might get you where you want to go, but not logic.

There are several potential causes for a cold start miss. One is a bad SAP. I am positive that is the case and have personally experienced those symptoms that were eliminated with a new SAP. Sometimes the rough idle is readily apparent, sometimes the engine is running smooth but is tacking up and down so little you have to read it from OBC. Rough idle usually disappears in under a minute. The Sap doesn't always sound different than normal.

This is one of those parts no one wants to replace because of the cost so they choose to agree with so many that have justified not doing so even with input to check it out as the potential core issue. They take the position it doesn't cause any problems, only there for emission standards. You have my input, anything more is not going to make a difference, will just cause a debate like what is the best oil or whether or not to change transmission fluid. Always your call.

I can't be positive your issue is caused by the SAP but it is a logical course of action to troubleshoot the SAP than experimenting with changing values when you don't know what they should be or what the changes will do, You have error codes, produced to facilitate troubleshooting and a troubleshooting procedure. Just trying to help. Always you call.

I wouldnt call it logical since the AIR does not change the air fuel mixture strategy during the CAT warm up phase. How can the difference in ambient air temperature cause misfires? The secondary air system will come on a cold engine at 0° or 5°.

The problem here is not the AIR system, and is most likely cause by uneven cylinder filling.