I have a 2007 R56 N12 "Justa" automatic with 140,000 miles on it. I bought from a guy that said it needed a new transmission speed senor. I drove it about 50 miles home and the only problem I had at the time is that it did want to shift gears. I finally got it to shift gears and drove it the 50 miles home. Bought new transmission output speed sensor and opened up the valve body and replaced it. No change in the shifting problem. Figure it was the shift solenoids. Bought them and replaced them in the valve body. It this point I saw I had an oil leak from the oil drain plug. Drained oil when I took the plug off and it didn't have the crush washer. Got the crush washer and refilled oil. No more leak.

Took it for a test drive and it shifted gears perfectly. Was pulling into my garage and engine stalled out. Now when I start it (cold start) it will idle rough and the idle will surge for about 30 seconds and then idle fine. I put it into Drive or Reverse and the car will start to move but then the rpms drop to about 400 rpms and then I lose all throttle response. Push the gas pedal and nothing, no change in rpms, they just stay at 400. Car kind of vibrates and stays like that. I will turn it off and restart and it will start idle okay for a minute then rpms drop to about 400 and can rev or nothing at that point. If I start it and rev it while I put it in drive it will go forward for about 20 feet then rpms drop to 400 and no throttle response.

I first thought bad fuel pump. Checked it out and couldn't really hear it when I put ignition in first position. So I replaced it. No change. Okay I thought back fuel pressure, maybe a clogged fuel filter. Got at fuel pressure test kit from Autozone and tested fuel pressure and get 5 bars. All good there. Spark plugs look good. At this point I figured I check the codes. Bought a OBD II wireless adaptor and used Troque Pro to pull codes. At first I had some transmission codes. Cleared them and they have never returned. The codes I currently get are P0011 and P1338, plus I will get a P0012 code occasionally. Using the Troque app I was not getting a MAF signal. Replaced MAF with no change.

Checked oil level and it is good.

Codes point to Camshaft sensor or VANOS Solenoids. I have a Countrymen that uses the same camshaft sensors and thats what the codes point to so I switched them out. No change.

Okay, maybe the VANOS solenoids. Pull them and they were kind of dirty so I cleaned them and put them back in. No change. Tried switching them from intake to exhaust and exhaust to intake to see if codes would follow. No change. What the hey, I'll just replace them. No change again. Also pulled the exhaust non-return valve and cleaned it.

So I pulled the valve cover and looked at the timing chain, guide, and tensioner. Chain was tight and guide looked to be in good shape. I have checked my plugs, hoses, and fuses and all seem good. I've also tried to unhook positive on battery (which is also brand new) and let set over night to clear computer.

Did some more research, maybe it is the throttle body. Part ordered and replaced. Still no change.

Seems like the warmer the engine gets the quicker it will drop the rpms to 400 and lose throttle response, but coolant temp reads normal (per Torque app).

I am at a loss. I can not figure out what the problem is. Any help or thoughts would be greatly appreciated.

New parts
-Battery
-Fuel Pump
-Transmission speed sensor
-All shift solenoids
-MAF
-Both VANOS solenoids

 

did you try to read the live data of the gas pedal and throttle body to see if they respond to you?

Can you check the compression?

did you try to reset adaptations? not sure how the app does it though.