Skoda Octavia Mk 3 2.0 TDI 150, 2016, Mileage: 270 K km.

My Skoda has been making some strange shakings since February. Around the time the engine heat hits 90 degrees, which is normal running temperature, the car shakes harshly, sometimes smoothly, sometimes just once, sometimes 2 or 3, or more, with irregular laps in the following 1 or 2 minutes. During these shakes, the rpm responds and it goes up and down, as I try to speed up to compensate it. After this, the car runs smoothly despite its mileage. I can come up to 140km/h but usually stay around 120-125 in the highway. No problem at all. I have never received any error message on the dashboard. The problem occurs in every ride, but not if the engine heat is already at 90 C.

During the last 4 months I have tried a lot, and changed a few parts. Lastly water pump, because “sporadic” water pump problems was registered (no dashboard error message shown at any time.) During the last 3 months: Lambda probe (lambda sensor) is changed. Fuel injectors are changed. Pressure regulator is changed. Electric system has been checked (with no errors). I did a diesel system cleaning treatment in March, with Syprin and changed the fuel filter there after.

Since the problem occurs when the heat achieves a certain level, (never below 80, anyway) I expect this to be a clue.

I will truly appreciate if you share your experiences and/or recommendations, would you have any of this kind. Thank you in advance.

NOTE 1. Another type of shaking (sometime after it is warmed up) is happening when I hold at the traffic light, both the clutch and brake pedals are down. In this situation the shakes are quite different but continues until I release the brake pedal little, may be a few centimeters or three. I do not know if these shakes could be related to the no. 1 problem, described above – because the second type of shakes started recently.

NOTE 2. 2 days before the problems occurred for the first time, I drew into a soft snow drive, appx. 30-40 cm. deep, and could drive back after half an hour’s struggle. The car was parked outside in the snow storm during the following 2½ day. I do not know if this has anything to do with the problem, but this is part of the story.

16 hours ago, OldCarpenter said:

Around the time the engine heat hits 90 degrees

So it does it at 90, or before it gets to 90?

16 hours ago, OldCarpenter said:

The problem occurs in every ride, but not if the engine heat is already at 90 C.

Because thos makes it sound like it doesn't happen if it is warmed up to 90? So how long before 90 does it run rough?

Eg, when you first start or say 5 minutes after?

16 hours ago, OldCarpenter said:

because “sporadic” water pump problems was registered (no dashboard error message shown at any time.)

Can you explain the sparodic problem? Why exactly did you change it?

16 hours ago, OldCarpenter said:

Since the problem occurs when the heat achieves a certain level, (never below 80, anyway)

So are you saying every time between 80 and 90 it runs rough but you can still do 140 kmh no problem?

16 hours ago, OldCarpenter said:

changed a few parts

I would avoid just changing parts without good reasoning because it will cost you alot and unlikely to fix much.

Really need to do some diagnostic work.

For example, next time it runs rough, try stopping and seeing if it idles or you can rev it freely in neutral?

Try turning the engine off and restart and see if that helps?

Does it blow black (or white) smoke when running rough?

47 minutes ago, BlueWagon said:

So it does it at 90, or before it gets to 90?

Yes. Only once it did that after 20-25 minutes drive, but in all other cases it was within the først 5-12 minutes. I twice tried to pull aside and waited for it will happen, while the engine running idle. It came, and then, I continued driving with no problem on the country roads and the highway. And it still does up to 140 km/h with no problem.

53 minutes ago, BlueWagon said:

Can you explain the sparodic problem? Why exactly did you change it?

The software registered this error and used exactly "sporadic" expression, then I said let's change it and see it, if it helps. It did not help. A car-electric specialist looked at it, and he said there is nothing wrong. A diesel specialist found 1 faulty injector and he replaced it. My all-round mechanic still puzzled. I agree that it costs a lot without a full diagnostic, but the software is not showing anything.

There is no black smoke or anyhting in that direction. The car uses very little oil for its mileage. I had to add appx. ½ a liter oil last weekend, 8,000 km after the engine oil change.

1 hour ago, BlueWagon said:

For example, next time it runs rough, try stopping and seeing if it idles or you can rev it freely in neutral?

Try turning the engine off and restart and see if that helps?

Does it blow black (or white) smoke when running rough?

I would not calling it running rough but making a strong shake. Stopping after it does once or twice would not make a difference since it will not repeat it again, I am thinking.

While the problems are happening, I do not have any problems in changing the gears. Sorry I forgot to say: This is a manual 6 gear version.

By the way: Thank you so much for you have taken your time to write back and follow my topic.