I have a 2013 r56 mcs, and ive been having some problems with it. It first started when i bought it, it was a minor like stumble and i thought maybe are the spark plugs cause i havent checked those, after a while i changed them, and my car had been working fine, after some while my car starts to get those stumbles but very aggressive and when im stopped at a red light sometimes the car shuts off. I changed the fuel filter cause i thought maybe it was clogged, but the problem persisted. It gets a very aggressive stumble (feels like a fuel cut) when im accelerating on light throttle, when i go WOT the car does not hesitate at all, but it feels i little bit slugish compared to when i bought it, and when im at stops the car sometimes struggles on staying on, and its difficult to accelerate when stopped, its like the throttle isnt right. And it idles at around 600rpms

if someone have had this before and can help I appreciate im new to the r56

 

Get yourself a mini specific code reader. Check you codes and get back to us.

 

Hi Bud, im dealing with something similar but my car does not shut off ever when im stopped, once its running it stays running.

On cold starts in the morning, it idles really rough, and ive been getting worse gas mileage than usual. Once its done idling rough for like 30 seconds it runs fine for the rest of the day usually but it is a bit slugish compared to when i bought like you said.

Right now my shop is trying to diagnose it, they tested the fuel system, vacuum system and the turbo for shaft play and everything seems fine along those lines so far.

So far i am still stuck

 

I do not have one close by, and i cant drive my car because when its warm thats when it starts to do every problem it has. But i have the ultragauge and it reads one code P0420, im pretty sure its a cat converter, but i really dont think the cat is the reason behind all of the problems

 

What the P0420 code means:

A P0420 code indicates a problem with the catalytic converter. The purpose of the catalytic converter is to break down harmful pollutants created during the combustion cycle. By using fine platinum and gold meshes to filter exhaust fumes, the catalytic converter is able to reduce the emissions expelled from the exhaust pipe.

The catalytic converter has two oxygen sensors. One oxygen sensor is positioned in front (upstream) of the catalytic converter and the other O2 sensor is positioned at the rear (downstream).

If the upstream oxygen sensor is working properly, its readings should fluctuate from when the car is at operating temperature and when running in a closed loop. If the downstream oxygen sensor is working properly, and there isn't an issue with the catalytic converter, its readings should remain steady.

When the oxygen sensors have similar readings to each other, it indicates that the catalytic converter is not working as intended. If the voltage of the downstream oxygen sensor decreases and begins to fluctuate like the upstream oxygen sensor, it means the oxygen levels are too high and the Powertrain Control Module (PCM) will store the P0420 trouble code and turn on the check engine light.

Common causes of the P0420 code?

• Damaged muffler or leaks in the muffler.
• Damaged exhaust manifold or leaks in the exhaust manifold.
• Damaged exhaust pipe or exhaust pipe leaks.
• A misfire in the engine.
• Oil contamination in catalytic converter.
• Faulty catalytic converter (most common).
• Faulty engine coolant temperature sensor.
• Faulty front oxygen sensor.
• Faulty rear oxygen sensor.
• Damaged oxygen sensor wiring.
• Oxygen sensor wiring that is not properly connected.
• Damaged oxygen sensor connectors
• A leaking fuel injector.
• High fuel pressure.

 

So i went to a me mechanic last week and he says the computer shows no code while doing the misfire or when it shuts off on its own, he says he changed hpfp, throttle and didn’t fix the issue, he changed the spark plugs to NGK, and i had bosch. And it fixed the problem for a week, now it started again doing the engine stumble it did before. Apparently its not aa clogged catalytic converter since we took off the oxigen sensor vefore the cat and it still shut off o. Its own like it didnt get enough gas.