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Clio 3 1.6 16v (K4M862 VVT) strange problem



  Clio 3
Hello, I'm here with a big problem. My car is a Clio 3 GT 1.6 16v 128hp engine K4M 862.
The first start of the engine sounds like that (check video -> https://www.youtube.com/shorts/8Z6y-VFxwSI), the revs oscillate and the sound of the engine is weird also the car fails to pass the emission test in my country (like the UK MOT).
The car in the video is revving alone without pressing any pedal.
Some days ago, I was to someone with the original Renault tester and I don't have any bad parameters, all things are good, with no misfire percents and no ECU errors. He checked also the oxygen sensors and there both are fine. So, he told me that there are 2 probably causes:
1. intake gasket - Maybe the car draws some fake air, but the problem is why after a maximum of 1 minute of revs oscillating all things are ok and the car can be driven well. This should have happened with the fake air all the time, so I think it's not a problem, I think.
2. solenoid? - The guy with the tester told me that I should change the solenoid with the dephaser pulley which is changed 1 year and 10 months ago with the timing belt and water pump in the same time (and after that change, I didn't make more than 7000 km with the car). I also started the car with the solenoid plug removed and it's the same.

Does anyone have other ideas? Or has anyone else had this problem?
After a maximum of 1 minute of letting the car idle, the idle is perfectly where it should be and the car has no more problems until the next day, I can start and restart engine all the day without any problem. And after it warms up, everything seems ok, and I can't figure out if I have any 'lack of power'. I also tried to disconnect the solenoid when I start the car at cold to see if it behaved differently, but it's the same.
Also, after that 1-2 mins maximum of rough idling, I can turn it off, wait for it to cool down, and if I start it the same day, the problem no longer appears, but the next day it appears again.
What I managed to figure out is that I have the value -23 on OBD2 at the LTFT sensor, and also the STFT is oscillating negative without reaching a value of 0. So, a large negative LTFT value is telling me there is uncontrolled/unwanted fuel being added to the mixture somewhere that the ECU needs to remove (thus negative LTFT) in order to get closer to the ideal 14.7:1 expected in the exhaust. What do you think? In 5000 km driven I didn't get any error on ECU.
If someone has any ideas... both O2 sensors are perfectly working
I would have left the car as it is, but the problem with the emissions test makes me do everything possible to fix it.
 
  Clio
From your description/testing.. it may also be a small airleak, when the engine warms up, expanding it seals and runs well.
Its not picking up many rpm.. so it may be something small.

If it was my car.. I'd check theese things:

-Map sensor O.R. (they are known to leak sometimes)
-spray with a carb cleaner spray or compressed air near intake joints and observe results. Any bigger fluctuation of rpm may indicate a leak.
-cheching the side of throttle body, there is usually a part (surely on the gokd side on mk2, not sure if needing to remove airbox on mk3) showing the return spring and the shaft. You can see if it stay still or if it moves. If its still it may be an air leak, if it moves it may also be something related to it. Maybe even the carbon canister solenoid.

Those are the first 3 things I'd check.
I had a similar engine with a similar problem driving me nuts some years ago.. and not only me.. 4 garages.
 


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