MINI Cooper Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
Hello all, I'm new to the forum so please be nice. I bought a Mini one R56 2008 about a year ago and it's been perfect until I tried to put it through its MOT.
It's failing quite badly on emissions. I've replaced the cat and both o2 sensors and took it back for an emissions test and if anything it's got worse. Prior to the first MOT I did all the usual things, Eng oil and filter, fuel additive, and a few long runs in the car. Since then I've changed the rocker cover gasket as one of the spark plug cavities was full to the brim of oil so was wondering if that may have been shorting that ignition coil and causing one cylinder to not be firing which could be causing the bad emissions?? I'm not sure if it's worth changing all the ignition coils anyway just for peace of mind. To me, the car sounds and runs great but other than something more sinister being wrong I'm a bit stuck!

Any help or ideas would be appreciated.

Cheers guys
 

·
Registered
Mini Paceman Cooper D MY2014
Joined
·
55 Posts
I would get a code read (taking note of any historical codes) and a live data log.
If no codes to take action on there's a myriad of things to consider.

Is the timing chain system in good order...Is the Vanos Solenoid functioning and it's wiring in good order?.any overlap of valve timing will cause an issue...or could it be coked up internally causing poor valve seating?

Does the engine reach correct temperature and is the coolant temp sensor functioning correctly?

A failing MAF doesn't always throw a code but can cause emissions to be poor. Live data read will show if it's within the defined parameters.

Is the car burning/using oil? Plugs out and a colour check will confirm, and whilst in there perform a compression check. This old fashioned check is still so very vital when diagnosing faults.Also check if spark plugs are the correct type and heat range.

You fitted a new cat & sensors. Were the sensors universal or vehicle specific? If universal they can often be an issue.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #3 ·
I would get a code read (taking note of any historical codes) and a live data log.
If no codes to take action on there's a myriad of things to consider.

Is the timing chain system in good order...Is the Vanos Solenoid functioning and it's wiring in good order?.any overlap of valve timing will cause an issue...or could it be coked up internally causing poor valve seating?

Does the engine reach correct temperature and is the coolant temp sensor functioning correctly?

A failing MAF doesn't always throw a code but can cause emissions to be poor. Live data read will show if it's within the defined parameters.

Is the car burning/using oil? Plugs out and a colour check will confirm, and whilst in there perform a compression check. This old fashioned check is still so very vital when diagnosing faults.Also check if spark plugs are the correct type and heat range.

You fitted a new cat & sensors. Were the sensors universal or vehicle specific? If universal they can often be an issue.
Thanks for the reply, I think part of the problem is I've fitted poor quality sensors, to be honest. Live data voltages of the pre-cat sensor are incorrect and I'm also getting a fault now on the pre-cat sensor for the heater circuit. I also had a leaking valve cover that filled one of the spark plug cavities to the top with oil so I'm guessing that would have caused some issues with the spark plug being shorted out and not firing correctly. The timing chain was very recently changed. I haven't considered the Vanos just yet. Engine and coolant temps are correct.
 

·
Registered
Mini Paceman Cooper D MY2014
Joined
·
55 Posts
Thanks for the reply, I think part of the problem is I've fitted poor quality sensors, to be honest. Live data voltages of the pre-cat sensor are incorrect and I'm also getting a fault now on the pre-cat sensor for the heater circuit.
..and that might just be as a result of the incorrect one-day sensor voltage. Did you change the cat and sensors solely as a result of the poor emissions or from fault codes and witnessing live data inconsistencies?

I also had a leaking valve cover that filled one of the spark plug cavities to the top with oil so I'm guessing that would have caused some issues with the spark plug being shorted out and not firing correctly.
...oil doesn't tend to cause tracking but even if it did, have you noticed an imbalance of the engine, i.e. missing spark?

The timing chain was very recently changed. I haven't considered the Vanos just yet. Engine and coolant temps are correct.
...I've read couple of entries on other forums whereby the solenoid connection had not been pushed home correctly rendering the Vanos Solenoid inop. If nothing else a visual check wouldn't go amiss.
 
1 - 4 of 4 Posts
Top