2.7t rough idle + jerking and shaking when accelerating gently
 

Hello Forum!

Currently I am stuck with my Allroad 2.7t, car which could have been so great... I have bought the car year ago and since then there was a problem with rough idle. After few months issue with jerking and shaking when accelerating occured (mostly when accelerating gently uphill, I haven't noticed it when driving downhill). Together with this shaking there is a deaf, very quiet "banging" (rubbing?) sound coming from below. It happens both on cold and hot engine. Mostly between 2000-2200 rpm or higher.

I am not sure if those are two different issues, or one causing another.

In the next days I will drive to the company where they repair automatic transmissions, guys should know if maybe it is the torque converter. But if so, why both symptoms occur together? If jerking and shaking is stronger, rough idle is stronger... Also on neutral.
When slowing down, right before stop, engine almost chokes + there is this black "coal" substance on the entire back of my car, coming from the exhaust.


When the car was bought there were errors:
P3262 - O2 sensors swapped + all possible O2 sensor errors- voltage too high, voltage too low, malfunction in circuits
Once there was P1857 error.
Always cylinders missfire, starting from 1,2,3, then sometimes it's present in 4,5,6.

So, the Grand Tour of repairs started, what was done:
1. Spark plugs and coils replaced, engine compression checked- it's better that stock actually... Also car has measured 255 bhp.
2. Both front O2 sensors replaced + timing belt replaced + all filters replaced
3. ECU replaced, as it showed some signs of previous repairs (there was some cable soldered, nobody knows why)
4. MAF was checked by unplugging it during rough idle- no change at all
5. There are no signs of vacuum leaks, but this was checked only manualy
6. Then I was told that the o2 sensors were really swapped, I mean the cables were swapped somewhere near the engine, so this was fixed. Also catalytic converters were verified.
7. After that, car was running great for few months and around 1000 km. I installed LPG and problem slowly returned... Both when I'm driving on petrol or on LPG. So there is one advantage of this situation- we know that it's not the injectors, because LPG has its own injectors. Also (but that I am not sure) it will not be the fuel pressure, right?
8. Few days ago there was another issue found- right chain tensioner and chain were not ok, so this was replaced + valve covers and gaskets were replaced.
9. Replaced shaft position sensor

Now, when I delete errors, first what occurs is P1136 after few minutes - Bank 1 system too lean. After some hours of running- cylinders 1,2,3 missfire.
Next are errors P0150 + P1128 + P0130 + P0138.
After deleting the errors car runs normally for about 50km (30 miles if you are outside EU :>)

What is interesting - when I drive the car really hard for around half an hour, all bad symptoms seems to dissapear for another half an hour. But I don't want to ride like a wind all the time (although it's a great fun in this car), no, I just want to find the casue and get rid of it once and for all.

At the top of that, ferret ate my hood insulation lately :). I need some serious help here.