12nz bad running when cold

[marc69]

My 1.2i sounds as though it isn't on all four cylinders for the first minute or two of running and it is extremely underpowered. There is also a little bit of black stuff coming out the exhaust (I assume oil or unburnt fuel from a cylinder not firing?).

Once it has gone a mile or two it runs fine and smooth.

There is no ecu light coming on when it is running.




I have tried a different coil and leads and it is the same.

[marc69]

anyone got any ideas please?

[stuarty]

Have u checked your dizzy 😵 possibly getting worn inside cap or rotor arm poor performance in cold moist conditions better when warmed by engine

[marc69]

I have changed the dizzy cap and rotor, it is not really affected by moisture, it is just if it is cold for the first few minutes.

[mowgli]

i'm assuming fuel & air filter have been changed, and plugs & leads too?

the CTS always is worth a look too

[marc69]

Ignorance here, what is CTS? Yes, the car had a complete service and still does this, not everytime, it is intermittent.

[bazzap8389]

Coolant temp sensor

[marc69]

Ah, that makes sense, any idea where it is on a 12 nz?

[marc69]

I think i found it, blue at the back of the inlet manifold. I'll try to get one this weekend. Thanks

Surprised the ecu didn't pic it up.

[Stuart]

The ecu might be looking for shorts to ground or 12v, but if the sensor is giving 'a reading' that is within those limits then it'll be fine but run bad