Couple issues with 3.0tdi quattro

[mikeya4]

Hoping someone might be able to help,

I have a 2005 3.0 tdi quattro and it has an intermittent rough idle, doesn't smoke just feels like its missing, drives absolutely fine and no fault codes on VCDS, any ideas or any tests i can run on VCDS?

2nd fault is when its warm and pulling out of junctions when turning either left or right the rear makes a rumble noise (hard to describe), it feels like something in the drivetrain as is worse under load, doesn't do it when cold and doesn't do it when pulling away straight, I have changed the rear diff oil but has made no difference

Thanks

 

[spartacus 68]

Intermittent rough idle could be injectors. If nothing on VCDS it can't be that serious I'd have thought. I've used a bottle of Forte diesel conditioner straight into fuel filter before on my old B5 2.5 TDI V6, then drove hard in 2nd and 3rd gears. Will smoke initially, but will clear. Replace fuel filter afterwards and top up with fresh diesel before turning over. Try Shell's V-Power diesel to see if there's any notable improvement.

Second fault. Any slack in prop-shaft before it reaches rear diff? Not sure if there's a central bearing carrier than can wear? Remember this on B5 model - so I assume it's on B7?

 

[Paul battams]

Hi I had rough idle on my 3.0tdi 05 vcds didn’t show up anything out of the ordinary sent them away 1 injector was out on low fuel idle replacement injector runs sweet as now.
And yes there is a centre bearing on prop but Audi won’t sell you it without the prop for 1k go on e bay there’s a few different hole centres take under guard off and measure it I got one for £54 not too bad to change just mark the prop before you split it in case it’s balanced up which it should be


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[mikeya4]

Perfect thanks for your help, I wonder if I do a leak off test at idle and see if any stand out, I read the injectors aren’t very good on the early ones, I wonder if they are a direct swap from a later version or not?

 

[Paul battams]

I was told a leak off test wouldn’t really help they need to be tested but it might point you in right direction I’m on 170k quiet heavily mapped and only replaced the 1 injector so they can’t be that bad


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[mikeya4]

Cool, did you have the same symptoms with the transmission noise? Thanks

 

[Paul battams]

Ye in a tight lock either way when warm seemed to clunk gearbox been overhauled and rear diff oil changed did centre bearing there is an ever so slight noise but my gearbox man but the last little bit of noise down to my harder wider summer tyres I run 245’s


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