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
Oh one other thing, the "you left your key in it" chime varies in speed. At any rate it sounds slower that the 2011.

 

First I would have to offer the opinion that the MAF and absolute throttle position readings with the engine off are probably not real.

What are they when the engine is running?

A cold O2 sensor is a bad sensor. The heating circuit is the #1 suspect, but a bad engine controller is also a possibility. However, given the car's history it could be the sensor wiring.Or if the car sat a while even rodent damage.

No variable idle speed with my MINI but with another car engine manifested this behavior twice. First time was an intake air leak the air/oil separator had developed a leak.Second time and the idle speed was going up and down from near normal to nearly slow enough that I thought the engine was going to stall. This turned out to be a bad variable camshaft timing solenoid/actuator.

 

Thanks Rock C for the input. I'll get the MAF and Throttle readings when the car is running. I have a cheap O2 sensor coming for test purposes and I'll remove the intake including the Throttle body and test for voltage and wiring condition. It might be a little while before the part arrives but I'll post my findings once I've completed the tasks.

 

Installed the new O2 sensor. The readings are the same as are the running symptoms. The O2 sensor is still only showing 14’C
I think it’s wiring or the ECU.