Diagnostický případ

Opravené vozidlo

Libor Fleischhans

Jazyk případu:

Engine vibration and shudder with rattle noise

25.08.2016 0 11216x

Informace o vozidle

VIN:	VSSZZZ1PZ8R026392
Výrobce:	Seat
Model:	Leon
Rok výroby:	2007
Kód motoru:	2,0 TFSI FR (Cupra)
Typ motoru:	BWJ
Výkon (kW):	177 kW
Převodovka:	Manuální
Palivo:	Benzín
Najeto:	69 610 km

neukládá žádný chybový kód

Doposud provedeno bez úspěchu

The dual mass flywheel was replaced, complete clutch and the variable timing actuator valve were also replaced.

Závěr

VOZIDLO JSEM NEOPRAVOVAL

Engine decarbonization was done in the end manually. The engine power was restored. The owner was disappointed by the TFSi engines character that he sold the car immediately despite the fact that he loved the car.

Obrázky, fotografie a soubory

Seat Cupra 2.0 TFSi 177 kW (7112/1)

Hot engine misfire monitoring (7112/2)

After the engine warms up I didn't like the way the engine started and idle. Idle was occasionally irregular with vibrations. The engine hesitated to accelerate from idle following previous deceleration and this acceleration was accompanied by a rattle noise. I was thinking this rattle noise could be caused by rapid openning of the throttle valve whne trying to save the engine from stalling. Usually the engine accelerated OK but once out of 5 to 8 accelerations the response was sluggish.

The engine ECU was monitoring engine misfires at idle, that were more frequent than on the picture but nevertheless were quite high for this engine.

Individual cylinder misfire (Turbo - LOG) from OBD connector (7112/3)

Even without using an oscilloscope I could see on the measured voltage on channel 33 (Lambda sensor voltage) oxygen shocks showing differences in oxygen contents in individual cylinders. I could tell that the A/F mixture wasn't burning correctly by hearing a flapping noise in the exhaust (in particular during acceleration).

Note: Some modern engine ECUs allow to increase the logging speed up to 4 times or even faster. In such cases if you are logging only one parameter the grapics can capture the oxygen shocks and you do not need to connect and use an oscilloscope.

Individual cylinder misfire – detail (Turbo - LOG) (7112/4)

Zoomed in oxygen shocks are showing differences in oxygen content residues in the individual cylinders. The mixture wasn't burning correctly in particular during acceleration.

Strongly carbon contaminated intake valves – cylinder #4 (7112/5)

The spark plugs were inspected and no problem found. Since the spark plugs were removed I also inspected the inside of the combustion chamber. I discovered that the intake valve stems were strongly contaminated by carbon deposits that restricted airflow into the cylinders.

Strongly carbon contaminated intake valves – cylinder #4 (7112/6)

The valves have strong carbon contamination that restricts airflow into the cylinder...

Strongly carbon contaminated intake valves – cylinder #1 (7112/7)

The valves on cylinder #1 are also strongly contaminated and restrict airflow into the cylinder...

The engineers are thinking about design but the technician has to find his way... (7112/8)

Engineering nonsense: The airflow sensor is integrated into the engine cover. If you were to require to connect and measure something when the engine is running or during a test drive then this is not possible with the airflow meter and this strongly restricts engine diagnosis.

Verifying camshaft position adjustment (7112/9)

Ï am not sure if it is normal on these engines that the camshaft position changes only by 26.5°of crankshaft rotation and doesn't reach a value of 28°.