Idle 780 rpm shaken slightly, but disappear at idle 950 rpm.

Idle 780 rpm shaken slightly, but disappear at idle 950 rpm.

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han95

Original Poster:

7 posts

55 months

Monday 19th August 2019
quotequote all
Hello everyone, my car is Passat B8 TDI 2.0 150hp
The car is not old, only 3 years and 40k mileage. Driving prefect and carry out the best schedule service.

I also own the 10 years 120k mileage golf mk6 1.6TDI, it is very quiet and no vibration in the car, even now.

For Passat B8 2.0 TDI whatever cold start or 90 degree normal temperature. I found when Idling 780 rpm slightly shaken, sensed by the steering wheel and the sun visor vibrates. (if compare with my old golf, no vibrationi on the sun visor at all)

However, when the idling speed rise to 950 rpm (during DPF regeneration), all vibrations disappear and the car is quiet.


What is the possible reason?


Some people said it is engine mount (but my car is new)? some people said the timing issue? I have the VCDS cable, how to check the timing or injector pressure?


Thank you very much

E-bmw

9,105 posts

151 months

Monday 19th August 2019
quotequote all
han95 said:
Hello everyone, my car is Passat B8 TDI 2.0 150hp

What is the possible reason?
It is a 4 cylinder diesel mate, it is never going to be smooth!

I suspect if you look at the idle speed of the golf it is slightly higher than the Passat.

Also, the car won't do a DPF regen at idle, so that isn't why the revs increase, it will be when the ECU decides to charge the battery or some other increase in electrical load.

han95

Original Poster:

7 posts

55 months

Monday 19th August 2019
quotequote all
E-bmw said:
han95 said:
Hello everyone, my car is Passat B8 TDI 2.0 150hp

What is the possible reason?
It is a 4 cylinder diesel mate, it is never going to be smooth!

I suspect if you look at the idle speed of the golf it is slightly higher than the Passat.

Also, the car won't do a DPF regen at idle, so that isn't why the revs increase, it will be when the ECU decides to charge the battery or some other increase in electrical load.
Thank you for your reply.
1, golf idle is 780 RPM as well.
2, very strange. if open the both golf and passat engine hood, I can see the golf engine is shaked more than passat engine. But in the car, the feeling is exchanged.
3, i also drive BMW 520d 11yrs and 100k mileage, it is also 4 cylinder, but more smooth.....
4, I also went to used car dealer to drive other passat similar age and mileage ,same engine, they are much better than my car.

So I believe my car may have some issue of idle.

btw, I mean if DPF regen during driving, and stop at traffic light, the engine rpm will keep at 950rpm.


Edited by han95 on Monday 19th August 13:06

GreenV8S

30,150 posts

283 months

Monday 19th August 2019
quotequote all
han95 said:
if open the both golf and passat engine hood, I can see the golf engine is shaked morn than passat engine. But in the car, the feeling is exchanged.
Perhaps the Passat has stiffer engine mounts which transmit more vibration into the car.

han95

Original Poster:

7 posts

55 months

Monday 19th August 2019
quotequote all
GreenV8S said:
Perhaps the Passat has stiffer engine mounts which transmit more vibration into the car.
thank you for your help

however
I also went to used car dealer to drive other passat similar age and mileage ,same engine, they are much better than my car.