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Discussion Starter #1
Good afternoon lovely people.

I really hope someone can shed some light on problem what I have.

Problem I have is quite common but nobody knows answer on this one(Spent over £400 in different garages with no luck)

At idle car is shaking. There is no rev hunting or stalling. No issues with starting car. No EML light.

Engine code CAHA
170 CR TDI

Connected VCDS and there no error codes.

Looking at live data I can see what actual rail fuel pressure at idle is jumping few points up and down compared from requested. There is almost no vibrations when starting on cold but when engine is getting warmer its getting worse. When DPF goes through regen vibrations are getting crazily strong to a point what you can see it from outside. Also at idle there is strong smell of unburnt diesel coming from exhaust pipe.

So far I've checked all 4 injectors and they all fine.
Cleaned out throttle body
Used redex


Things I haven't done

Checking EGR valve - don't think this could be the case as eml light would come out.
Changing fuel rail sensor - Disconnecting sensor doesn't make much difference.


Also my DPF pressure sensor needs replacing as its packed up but again I can't see connection between pressure sensor and jumping fuel pressure in rail.

My next step would be AUDI garage but I've heard a lot of bad things about them.

Did anyone had similar problem? What other parts could cause this?

If anyone could help that would be amazing as I'm on edge of selling this car.
 

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Check for vacuum leaks. When the engine is cold, the rubber hoses are stiffer and may hold vacuum better. Once warmed up, the rubber softens and the leaks start to impact the engine.
 

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Discussion Starter #3
Thanks for advise findalex

Spent few hours checking hoses and pipes. Unfortunately nothing but I might missed few as car need to be lifted.

Let's hope audi service is open this friday.
 
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