I just got this 2009 mini convertible (non-turbo) and it's been a pain so far. When you start it, it chugs like the idle goes up/down/up/down, etc. you also have to feather the gas pedal to get it to start. After doing some research online I thought it was a bad vvt solenoid. I replaced both of them. I noticed the crankcase breather hose was broken so I replaced it and while I had the intake manifold off I replaced the gaskets. None of this helped. After a lot of digging around I did find the large weird looking blue plug in the front that goes to the front o2 sensor and a few other places had some bare wires so I repaired those but that did not help either. The only codes it has are multiple misfires and a misfire code for each cylinder separately. I drove it around a little and it really didn't drive too bad other than it bucked really hard when I let off the gas like a manual transmission would if you slow down too much without pushing in the clutch (This one is automatic trans) The surging idle isn't quite as bad with the air conditioning on or when the cooling fan kicks on but it still does it. What has me perplexed is I can unhook the mass air flow sensor while it's running and it makes no difference, Also I tried unhooking the VVT solenoids, the plug going to the o2 sensors and there was no change either. I'm not sure if the crankshaft or camshaft sensor is the one closest to the front but when I unhook and reconnect the one in front no matter how many times there is no change. The one towards the back will occasionally make a difference if I unhook and reconnect it. Is there a "limp mode" that the ecm goes into when a certain sensor is bad or timing is off or do I have an electrical issue common to almost all of those sensors? I checked every fuse in both fuse boxes, the only one bad is a 5 amp fuse that says it's for a built in cel phone and it blows as soon as I replace it but there is a crap ton of corrosion in the connector in the center console that I'm assuming a factory cel phone goes in. I purchased the service manual but there are no voltage checks or pinouts of the sensor connectors or ECM plugs. I'm an electronics service technician so I can fix the wiring if it's an electrical issue. I just wanted to make sure first that the ECM wasn't just ignoring all of those sensors in some sort of "safe mode" Has anyone else ran across this issue? I already had to replace the footwell module and one of the plugs on it because water was leaking in due to the seal being rotted along the wiper cowl. That got all of the headlights/brake lights etc working allthough the Brake light is still lit on the dash for some reason. Thanks in advance

 

I have a 2010 justa that had idle issues and they disappeared after changing the fuel filter. You could try that because it seems you’ve covered most basics.

 

Multiple misfires could be bad coils and plugs. Have you scanned for codes if so, post them so we can help.

 

^This.

Also, make sure it’s a BMW/Mini code reader, not a generic “AutoZone” OBD code tool.

My gut wants to say carbon build up in the intake ports, or fuel pump... But, I’ll hold judgement until we see codes.

 

It really can be a laundry list of stuff. Codes will definitely help us help you, Instead of just throwing money at it.

timing chain could have skipped a tooth, bad pcv, valve hit piston, etc, could be 1000’s or could be 100’s.