Not really sure if there's a better place to post this but I'll try and keep it brief. Wifes got a 2004 clio mk2 1.4 16v, was running great for a long time then all of a sudden refused to start properly and was hard to keep running. Once it started it seemed to be okay though. I did some googling and cleaned the CTS, cleaned the fuel filter (crazy design!), replaced the MAP and intake air temp sensors, replaced coilpacks and spark plugs, and finally made sure throttle body was clean, air filter was okay and oil level is perfect. 

 

Now that I've replaced the MAP sensor the car won't start with it plugged in, if I unplug the map sensor it will start and run like an absolute dog, I can then plug the MAP in whilst running and it makes no difference to the running. I wonder if the new sensor is a duff? I drove the car round and it sounded awful and would barely accelerate, but then I guess if the sensor isn't running this would be expected.

 

Once the car starts to warm up the exhaust smells sulphorous/eggy, does this mean the catalytic converter is blocked up or dead?

 

My only other thoughts are that there is a very slight leak in the intake manifold pre-MAP sensor, as it's not turbocharged and before the sensor I guess this isn't a big issue though. When I pulled the sparkplugs they came out wet with black deposits. 

 

 

I would have thought one of the first sensors likely to fail would be the exhaust oxygen sensor which means the ECU doesn't know whether it's too rich or too lean if the sensor fails

To me it's the beginning of a search.............not that it's happened to me .........yet