Nissan Xtrail revolutions go up and down

Hello everyone, I have a problem with a Nissan Xtrail Turbo Diesel 2.2 year 2005, when I want to turn it on in cold it costs me until I give an accelerated already light, I have to have it accelerated for a while so that it does not go out, but then there are the tacometer needles up and lowering the revolutions to which it is scanned and it does not throw failures, it was made tuning, change of oil and air filters , Ignition spark plugs, cleaning in the EGR, well a good rudition and it is still the same I am worried please someone can help me, they tell me that it could be injection problem, or the injection pump, but your thing turns out to be something simple and I do not realize, these cars are very complicated and expensive the spare parts sometimes help them to Japan, I will appreciate their help.

That they check the flow and the accelerator potentiometer and if these are well sure you have to start looking at the injection.
You can also try to pour an additive gasile of cleaning the cleaning although if it does not give you pulls I do not think it is dirt.

I hope it serves you.

Thank you Diego, but I would like if the discomfort is not so much that it explains that it is the potentimetro and the flow rate, maybe I do not know the technical name because I do not have enough experience, and where they are located in the engine, I will appreciate the information a lot because I like to learn from experts like those of these forums, who help the rookies like me.

Sorry is Diego, excuse me but look bad for your name thanks for your information and you run the name of David for Diego's name. It is that this car has apologies crazy.

The caudalimetro is a sensor that measures the amount of air that enters the admission collector and sends this information to the UCE to inject the appropriate amount of diesel, is the side of the air filter is usually screwed to the same box is part of the tube and has a connector.

The accelerator potentiometer is what replaces the accelerator cable that old cars had to the end of the pedal and is responsible for communicating to the UCE the position of the pedal; A failure in this can make the engine accelerate alone.

These pieces in many cars do not fail when they put the machine.

I hope to help you luck