Low power 1.9 TDI 115
Low power: Simultaneous Factors?
First of all, thank you very much for the information. I learnt in some days more than by assisting my father to tinker his Peugeot
The problem
I noticed some months ago a whistling just after stopping the engine. It seems that it came from the catalyst. My garage owner found nothing of abnormal. Then, this noise disappeared.
There was also a sort of smell of exhaust gas.
At the same time, the engine switched to limp mode (rough low power). My garage owner cleaned the EGR, but the problem persisted. He suggested then cleaning the turbo.
I then made move the VNT stalk. This operation doesn’t resolve the problem.
During the time of reflection, the Low power and the switches to limp mode become more frequent, even from the first meters of the first hill… The Low power became permanent.
At the same time, appeared a consumption of cooling water and a light smell. My garage owner put the cooling circuit under pressure and found no leak. I am nevertheless going to change the thermostat.
Concerning the Low power, he suspected the MAF sensor by saying I could by lucky.
To verify, I disconnected this sensor. I noticed an increase of power. The car better took up hills.
I thus changed the MAF sensor but it doesn’t resolve the problem.
The tests
I learnt the existence of the cable VAG-COM as well as a heap of information about turbo-compressors and engines TDI. Thanks again. I became better equipped than my garage owner. In fact, I live in the country side and the nearest VW and Ford garages are 30 km far.
The tool of diagnosis VAG-COM finds this, which directs to N75 fail:
17964 / P1556 - Load(Charge) Pressure Control: Negative Deviation.
I noticed visually that the VNT stalk doesn’t move.
To verify it by driving on road, I placed a scrap of paper in the abutment of the stalk near the depression valve and drove the car by hills. The paper did not move in this experience.
In a second experience I reset many times the management unit of the engine, switching off/on
the ignition. Suddenly, the car accelerated with a little of delay with regard to gaz pedal. It pushed me… then… the limp mode again. The scrap of paper had disappeared.
I made measures with cable. The following tables recapitulate the results:
MAF /EGR duty
EngineSpeed/MAFSpecified/Actual MAF/EGR duty cycle/ Coolant temp.
903/Mn 260.0 Mg / R 396.9 Mg / R 84,5 % 27.9°C
903/Mn 250.0 Mg / R 377.3 Mg / R 84,5 % 63.0°C
2331/Mn 260.0 Mg / R 362.6 Mg / R 84,5 % 71.1°C
3066/Mn 350.0 Mg / R 372.4 Mg / R 84,5 % 70.2°C
Pressure
EnginSpeed/SpecIntakePress/ActualIntakePress/D.CycleMAP/Coolant temp.
903/Mn 999.6 Mbar 999.6 Mbar 19.9 % 72.0°C
1743/Mn 1050.6 Mbar 999.6 Mbar 59.0 % 72.0°C
2898/Mn 1173.0 Mg / R 1020.0 Mg / R 50.2 % 52.2°C
2982/Mn 1183.2 Mg / R 1020.0 Mg / R 50.6 % 72.9°C
I noticed that, by accelerating between 903 and 1100 / mm, the actual pressure less is than the atmospheric pressure and the specified pressure.
I did not make measures by driving, because it is dangerous.
What diagnoses?
Actually, I do not know. That is why I raise the problem.
I think however that the problem comes from one of following devices: N75, MAF sensor or G71...
By hoping that the problem and the tests which I made shall help, I ask you to help me to find out the exact cause. D’avance, merci beaucoup.
Anne-Marie