A4 2.0tdi sluggish and feels hesitant

GinG · 12 Jan 2016 at 10:17

Morning All,

Been away for the weekend and whilst driving to our destination I noticed when the accelerator was depressed for say an overtake there was a shudder/hesitation under acceleration, foot to the floor and the car would struggle to go past 60mph...we could get up to 80mph with a progressive acceleration.

Taking a big hit on fuel consumption also.

Same thing happened on the way back...is this the DPF regeneration thingy mabob doing its thing? Never really noticed this before in the 4 years of ownership coming up.

Alternatively could it be something to do with the Multitronic box? Shift seems smooth and no crazy change in revs to suggest this though.

Thanks

Jamesyboyjim · 12 Jan 2016 at 10:22

Its not going to be a blocked filter is it?

slick rick · 12 Jan 2016 at 10:40

Could be a blocked DPF? You need to get the codes read if possible.

paradigm · 12 Jan 2016 at 10:44

My guess would be a sensor. Possibly MAF.

peige · 12 Jan 2016 at 11:05

Does this engine have a EGR valve? Sounds like the symptoms my astra had when mine had gone.

GinG · 12 Jan 2016 at 11:14

Will go out have a look at the filter now and see.

Driving around town and sedately on an A road at 60mph you wouldn't think there was any problem, but when you try to accelerate hard there is just nothing there and like I say at 60mph foot to the floor nothing happens.

slick rick · 12 Jan 2016 at 11:18

Have you got any warning lights on the dash?

FiremanSam · 12 Jan 2016 at 11:58

I had a similar issue on my Mondeo TDCi and it was a split turbo pipe.

GinG · 12 Jan 2016 at 12:53

No warnings or anything on Dash, going out now to have a look whilst it is dry.

iaind · 12 Jan 2016 at 13:04

Check the air filter too - had this in a mondeo. Despite apparently being changed at the services, it was totally blocked to the point it was being sucked up into the filter housing and distorted

GinG · 12 Jan 2016 at 14:12

Been out to check the car again, opened up the air filter and looks brand new.

If I get chance later today/tomorrow I will take it for a good blast up some roads in manual mode and keep the revs high to see if that helps. Failing that will just take it to the garage.

-Mike- · 12 Jan 2016 at 14:16

How's the fuel filter? I had this kind of thing.... Gentle acceleration no problem but foot down it felt like it had hit a brick wall and didn't want to go anymore.

I may have missed it but what year? Is it a PD engine or CR?

GinG · 12 Jan 2016 at 14:49

Year is 2006/56 which I believe sits into the CR range of engines?

No idea how to check the Fuel Filter, got to do around 600+ miles next week. Is it worth giving the car a good run out before taking it into the garage?

Gambisk · 12 Jan 2016 at 14:59

Sounds like it needs an Italian tune up

-Mike- · 12 Jan 2016 at 14:59

2006 is PD engine not common rail. When was the fuel filter last changed? I have a 2007/57 with the PD engine with very similar symptoms. Pick up a fuel filter from your local dealership and swap it yourself if it's old?

When you do change it, pay attention to the fuel in the housing, if it's black / oily this can indicate tandem pump problems also.

Edit: when the master tech came out with me he went to overtake something and actually couldn't get power to go past it without feeding the throttle in: fuel starvation caused by the filter.

Orionaut · 12 Jan 2016 at 17:08

If this is the engine I am thinking of, the vac actuators for the variable vane turbo are prone to failure.

This can result in this sort of behaviour.

This usually generates a fault code however. It is easy enough to test though. Just disconnect the vac pipe and connect a length of tubing that you can suck on. It is easy to tell if the diaphragm is leaking or not.

It is a bit fiddly to replace however. There is a nut that you may need to make a tool for (The recommended tool is a 10mm half moon spanner but I found that I needed to make my own to get the curve right) otherwise it is a manifold off job.

-Mike- · 12 Jan 2016 at 17:15

Orionaut said:
If this is the engine I am thinking of, the vac actuators for the variable vane turbo are prone to failure.

This can result in this sort of behaviour.

This usually generates a fault code however. It is easy enough to test though. Just disconnect the vac pipe and connect a length of tubing that you can suck on. It is easy to tell if the diaphragm is leaking or not.

It is a bit fiddly to replace however. There is a nut that you may need to make a tool for (The recommended tool is a 10mm half moon spanner but I found that I needed to make my own to get the curve right) otherwise it is a manifold off job.

Overboost would throw up the MIL on this lump though!

Orionaut · 12 Jan 2016 at 17:44

-Mike- said:
Overboost would throw up the MIL on this lump though!

Like I said, this fault usually generates a fault code. But it is still worth checking since it is so easy to do.

GinG · 12 Jan 2016 at 19:27

Text a friend who owns a VAG specialist garage, see if he can fit me in tomorrow. Work covers car expense so not going to bother faffing on.

Cheers anyway guys, initial thoughts are a fuel filter as most of the faults mentioned should bring up an error on the dash...which it aint!

Will update once I find out what is up

GinG · 13 Jan 2016 at 16:15

Well it was the fuel filter. The gunk coming out of it was like treacle!!

Changed filter and added some cleaner additive and much better. Going to fill up with Diesel Ultimate over the next few times and should be nice and healthy again.

We weren't actually too sure if it has ever been changed the state of the gunk inside it!