This problem happens very rarely when starting my c max 2 litre diesel from cold the engine sounds very rough and it wont rev.if i turn it off and start again usually its ok

Sounds like piston blow by, as the gap increases and diesels have such high compression. When the turbo kicks in, the pressure is restored.

https://www.google.com/search?q=Toyota+Corolla+2+Litre+diesel.+Why+loss+of+power+at+low+revs+when+warm

..

Tata Nexon is the subcompact 4-metre SUV from the Tata Motors, which has created a lot of buzz even before its launch. I don't expect the Tata Nexon gets a CNG kit and it only offered 6-speed manual transmission. Here I specify some of the Tata Nexon specifications, have a look

=> It is available in both the engine. The petrol variants carry 1.2-litre Revotron which produces 110 bhp of power & 15-17kmpl of mileage while diesel have 4-cylinder 1.5-litre Revotorq engine which makes 110 bhp of power & 21-23kmpl mileage.

=> 6.5-inch touchscreen infotainment system, automatic climate control, dual front airbags & reverse parking sensors

=> Three drive modes Eco, City and Sport

There are several possibilities for this problem. A "cold start" sequence is suppose to activate based on water temperature and the signal from the water temperature sensor. This makes the fuel rich and adjusts timing to make the engine run better when cold. It works like a choke only it is electronic.

There may be 2 sensors with one making the dash gauges work and the other doing the engine controls. If not 2, then 1 sensor would do the whole job.

Another possibility is an air leak in the fuel system which makes the system bleed dry overnight. It is far less common on gas engines but happens a lot on diesels.

Some earlier Ford engines from 1984 to I don't know when they stopped on trucks, would use a step-up solenoid on the accelerator bracket that worked off water temperature. Sometimes a bad water thermostat would make the temperature controls malfunction the other way (High idle, clicking, low idle) that would stall and engine as the temperature vary.

Sounds like a sensor but what one and where ? take the air intake pipes off and check for oil inj the pipes as it could be the turbo is past it and its throwing oil into the intake pipes which is stopping the sensor from working once the oil builds up ,once its left the oil drips off allowing the engine to run again

No. Diesel engines have very high compression and require powerful starters to turn over. Cold engines turn over even harder. Batteries for Diesel engines must be robust. Cold weather robs batteries of power. If the battery is more than 2-3 years old, it is probably the battery, but definitely NOT the glow plugs.

if it is fuel waxing try addind small amount of petrol to your tank i.e. pint of petrol to 5 gallons of diesel

possible engine internal damage from the cold
have a compression test done
try testing the boost pressure from the turbo as it may not be working
excessive smoke and low power indicators
starts and runs cold is not indicated that it is a pump

Sounds like not all the glow plugs are working.It should run fairly smooth on a cold start if all of the glow plugs are working..Also you shouldn't drive off on a cold start with a diesel,Its really hard on the motors..At least give them 10 to 15 min on a cold start..The oil in them is a really thick oil and when there drove on a cold start theres no oil lubricating the internal parts and will cause the motor to seize up..You may already no this and dont mean you drive it as soon as you start it i just wanted to let you know..When you get alot of white smoke it could be two things,Theres water in the fuel which will make it not have much power die and smoke..But if it runs fine when its warm theres some bad glow plugs...Hope this helps you and have a great day

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_a3369546f8067589

try checkin your idle air control. most of the time it is a vacuumn line going into intake.pull it off and if the car revs up dont worry, it wont hurt it. if it does simply put it back on, if it dies you have a bad vacumn.