Turbo & RPM issues

[vivasjm]

Hi all, the past week I leave my NP300 2019 2.3 Biturbo manual in the mechanic because I'm having an issue, for some reason when I push the acelerator to the bottom revs in 3rd, 4th or 5th doesn't go over 3500RPM.

today the mechanic told me that there is a kind of overpresure in the turbo, if he release some preaure from turbo revs go to 5000RPM at will, he also told me that he removed from ECU the turbo preasure limits but if he set the turbo at maximum presure revs doesn't go beyond 3500RPM.

Does anyone know what can be restricting the RPMs?

He did check turbo, intercooler and hoses, everything is fine

 

[tweak'e]

couple of things come to mind. one is its a form of limp mode.

the other is its not reading the full airflow. i would check the MAF sensor its probably under reading the airflow and check the intake piping for cracks/splits. it may be sucking in unmetered air. maf sensors are known to get dirty and miss read.
maf sensor does the fueling so if not enough air through it your not going to get full rpm. also if your hitting full boost ecu may limit fuel to stop over boost. bleeding off boost pressure is allowing more air to be pulled through the maf sensor which will let the ecu inject more fuel.

 

[vivasjm]

thanks for your reply, before going to the mechanic I cleaned up the MAF sensor and change air filter.
I have the feeling to that it is related to the air intake but the mechanic told me that boost sensor is getting good values, this sensor is at the air intake manifold end, after the intercooler. So if I get good turbo pressure at intake manifold end is there still the possibility of poor airflow level at the air filter end? before turbo?

Another thing I was thinking as it reaches 3500/3800RPM top is that maybe the wastage valve might be failing causing the big turbo doesn't get exhaust gases from the small turbo.

There is no DTC code registered during the last test the mechanic did, the first time I noticed this issue I get a "high pressure turbo" code and the np300 didn't go over 100km/h till I cleaned up the fault

couple of things come to mind. one is its a form of limp mode.

the other is its not reading the full airflow. i would check the MAF sensor its probably under reading the airflow and check the intake piping for cracks/splits. it may be sucking in unmetered air. maf sensors are known to get dirty and miss read.
maf sensor does the fueling so if not enough air through it your not going to get full rpm. also if your hitting full boost ecu may limit fuel to stop over boost. bleeding off boost pressure is allowing more air to be pulled through the maf sensor which will let the ecu inject more fuel.

 

[tweak'e]

thats a possibility to. if its choking because a bypass is not opening. tho it should be easy enough to check they are working.
do you remember the code at all?