Trying to fix hardware problems by accessing ECU calibration is the most backwards way there is.
If the ECU is stock and the binary is verified to be OK, then leave it alone. It is not your ECU, it is something broken with your car.
Your vibration can be a dual mass flywheel on the way out, uneven compression, dirty injectors, bad spark plugs and so on.
The ECU is the last place to check for such things, as by doing this you are basically saying that Skoda and VAG did not know what they were doing when they were calibrating this engine, and this is a pretty bold statement.
Hi prj and esilviu,
Yes, you are right in general but it was a final workaround trying to eliminate the vibrations. But here is the complete story. I would be glad if you could advise some more things to find the real reason.
I've noticed this vibration when the car were 4 years old (ran about 38000 Kms). The engine has not started correctly and viblated severly. I've stopped and for the second case it started correctly. There were no DTC. When this happens 4-th case there were a DTC about random misfires.
So first the throttle body was cleaned and the spark plugs were changed. Everything OK for 2 or 3 months but then the vibration were noticed again and happened once or twice a month. Then the following parts were changed or checked:
Ignition coils were changed in pairs (two at a time) - all was correct.
Injectors were cleaned with a STP injector cleaner.
Coolant temperature sensor was checked - it was OK.
Checking the fuel pump pressure - it was OK (1,5 - 3 bar).
Fuel filter was changed.
Injectors were cleaned with an ultrasonic cleaner.
Checking the Manifold Air Pressure - it was correct. But finally I've changed the MAP sensor (by an original BOSCH made one) despite the correct pressure values, but the vibrations remained.
The compression and the pressure drop was checked by cylinders - it was OK.
The vacuum pipe of fuel pressure regulator was checked - it was OK. (See the problem of livslx)
Meanwhile I noticed that the vibrations happen when the engine starts at ~900 RPM (not 1200 RPM). Then I investigated that engine starts lower RPM than 1200 when the coolant temperature is lower than 18°C.
After that my car mechanic (who knows my car from its early ages) says that there could be only the ECU which causes this problem. We thought that it is not normal that the engine starts at lower RPM than 1200 but finally it turned out that it is normal (see later).
Then the car was checked by an official Skoda Service and a specialist who could detect the vibrations but he could not find any faulty signal or value during the tests.
After that I replaced the ECU by a new one (exactly the same as the original of the car (036 906 032J 4413). Nothing has changed. The engine behaves the same way.
Meanwhile livslx checked his car (an AXP Golf) cold start procedure and he said that his engine behaves the same way. It can start at ~1000 RPM when the coolant temperature is lower than 10~15°C. And I asked my friend (who has a BCA Octavia newer than mine) to check the cold start of his car and he confirmed what livslx said. So it is normal that at lower temperatures the engine starts at lower RPM but it seems that the RPM value and the temperature limit slightly differs by cars.
After that I've increased (+20 RPM) the idle speed and there was no vibration ever since (six months). Now I'm curious what will happen in winter.
(There is no dual mass flywheel in my car.)
So if you have any good idea what could be the real reason of these vibrations or you think that I missed something to test please post it. And I'm also curious about what you, esilviu, will find as a reason of this problem.
Thanks in advance.
Best regards,
