a6 c7 2.0 tdi cnha start problem

[johnydriver]

Hello. 
a6 c7 2.0 tdi 190hp cnha 2015.
No errors on board or on tester.
8/10 times when i start the engine - the car start to shake like crazy, and engine is making crazy sounds and shaking too... 

First it was 1 from 30-40 engine starts, now its 8 from 10... please, help who know what is that.

video: 
https://youtube.com/shorts/Or62SApyO3w?feature=share

[johnydriver]

IMPORTANT: this happens almost only on cold start

[Steve Q]

Id say look at maf sensors, crank sensors, cam sensors etc. However you'd expect fault codes if these were failing. 

Could it be engine or gearbox mounts? 

[Stevey Y]

7 hours ago, johnydriver said:

IMPORTANT: this happens almost only on cold start

My thoughts entirely Steve and depending on the milage they all fail between 80-100,000 miles the clue is its getting progressively worse which would be the loss of oil from the mounts.

Steve.

[johnydriver]

Hi, Steve

i have 0 errors on board nor with tester. 

yesterday at cold start it happened 4 starts in a row. Then it started normal, like nothing happened before... and all day it started like new,  drove about 250 miles and had about 8-10 engine starts on warm, and everything was good..

Stevey Y, 

it’s not only shaking, the engine is working differently, when you push acceleration pedal, he is making very scary sounds, and its gaining RPM very slowly, even if you push hard the accel. 

and if the engine is starting normaly, he is not shaking at all, no creepy sounds and no power loss...

thats why i dont believe in mounts... maybe sensors, but again, why its happening on cold start or after engine was off for an hour or more? no problems on warm

Edited April 17, 2022 by johnydriver

[Stevey Y]

4 hours ago, johnydriver said:

Hi, Steve

i have 0 errors on board nor with tester. 

yesterday at cold start it happened 4 starts in a row. Then it started normal, like nothing happened before... and all day it started like new,  drove about 250 miles and had about 8-10 engine starts on warm, and everything was good..

Stevey Y, 

it’s not only shaking, the engine is working differently, when you push acceleration pedal, he is making very scary sounds, and its gaining RPM very slowly, even if you push hard the accel. 

and if the engine is starting normaly, he is not shaking at all, no creepy sounds and no power loss...

thats why i dont believe in mounts... maybe sensors, but again, why its happening on cold start or after engine was off for an hour or more? no problems on warm

Hi the engine mounts are controlled in the same way as Mag ride shocks with electrical current, the mounts DO NOT throw up a code when worn out my engine was shaking before I replaced mine and the ECU will cut the power on the engine when the mounts are excessively worn to stop the engine from twisting so its worth a visual check and wiping around the mounts with clean kitchen towel to check for oil, the only sensor that would cause that sort of problem otherwise would be the MAP as that has two elements one of which runs the lower air path when starting and you need very sophisticated software to read the function, which type of diagnostics are you using if its VCDS depending which version you have you might pick the problem up on the live data.

Steve.

[johnydriver]

Thank you, Steve

i’ll check what you said. 

Happy Easter 🤝

[evopilot]

only thing that would make me not believe it was the mounts is that the problem suddenly goes away on the 5th start or so

map does sound like a strong likely candidate imo

[OvYd3L]

Hello! how did you solve it?

[OvYd3L]

nobody? i have the same symptoms on A6 C7 2.0 TDI CSUD 110 KW.. no errors stored in vcds/odis/obd11