Hello all. New to the Forum.
I am battling a pitching idle on a 2007 Base Cooper non S, with stalling. My scanner shows the AFR from the MAF sensor fluctuating between 0.75 & 0.77 g/s on a cold engine not running. Also the Absolute Throttle Position constantly bounces between 19.6% and 20% again , engine is cold and off. This is not the behavior I see on our 2011 Cooper S under the same conditions.
The back story to this car is it was involved in a light front end accident. I purchased it with the damaged "repaired" or thrown together as I like to call it. It was giving a CEL P0015, after 30 - 70 miles of driving, the engine would also, sometimes pitch between 700 and 1200 rpm on idle.
I changed the cam shaft sensors and then the VANOS solenoids with no luck. After quite a bit of reading I decided to look at the timing chain condition. The top guide looked rough so given I had not idea what level of service this thing had received, the car has done over 100k and I am a glutton for punishment, I decided to change the timing chain and while I was in there I replaced the timing gears. So chain changed now I was getting a P0012, but this time it was coming on within a few minutes of the car running. I rechecked the physical timing, all looked good. I decided to invest in a new code scanner as mine was very basic, so I purchased a Launch CR129.
On first use I could see the advance moving for both, so the new gears and solenoids seemed to be working. I decided to disconnect the cam sensors. When I did this the engine smoothed out, the revs dropped to around 800. I plugged them both back in and the engine remained even. I revved it a few times, as it settled it would pitch a tiny bit but would settle down.
I took it for a drive around the block. It stalled twice but as the drive progressed it smoothed out and I thought I'd reset something and fixed it.I left the car to go cold. I started it back up and it pitched for a minute then settled. I took it for another drive and there was still some hesitation. I did some more reading and new plugs and fuel cleaner was suggested as a fix for the remaining symptoms. I hadn't given it new plugs yet so I did that and added a fuel system cleaner.
Now I'm back to it pitching, I tried to drive it again but it was son bad this time it would stall out and I only just got it home again. I switched thew plugs back - still undriveable
The only codes I am getting now is P0300 & P0301 - 0304 for all the misfires, but no longer get a P0015 or P0012 codes but then again I can't drive it
Lastly we have a 2011 which is running fine so i thought I would compare some readings.
With the 2007 off and cold I get the following odd (to me anyway) readings
So this brings us back to the AFR from the MAF sensor fluctuating between 0.75 & 0.77 g/s on a cold engine not running, the Absolute Throttle Position constantly bounces between 19.6% and 20% again , engine is cold and off. Also the O2 sensor 1 is showing a temperature of 14'C whether the car is running or not. The 2011 does not do these things.
I have check the wiring harnesses and can't see any damage but a wiring issue seems the best fit (to my limited knowledge)
So there, as you see I need some help, I throw down the gauntlet anything anyone has would be a huge help. Thanks in advance

 

I’ve had a similar issue with rough cold idle since October and also surging when accelerating . I did a bunch of stuff that never seemed to fix it for more than a day. Last week I changed the PCV and it made a big difference. Still a little bit of rough idle, but it’s much improved.

 

I will have a go at this. There are some problems that will keep the ECU in open loop before and during running. A faulty thermostat for example but you would get a code for that. Next, the bank 1 pre cat Lambda/O2 sensor if partly faulty will throw the ECU out. Yours is giving a constant temp - this indicates a fault. Unfortunately if these engines are run for a long period with retarded timing (i.e. when the chain is stretched/worn) they damage the O2 sensor and cat. If you do change the O2 sensor I would recommend Bosch and not cheap aftermarket and after fitting reset all ECU adaptations. A new O2 sensor solved my fluctuating idle and stalling and vastly improved my fuel economy - running in open loop reduces fuel economy because the ECU is not regulating the injectors as it is not monitoring any of the sensors in this state = over fueling.