help required please!!

[lee1989]

My car hasnt been running right lately, feels very shaky when picking up speed as if im on and off the throttle, and also feels very under power, no fault codes at all, ive changes the n75 valve and its had new spark plugs, what else could it be? any help is much appreciated, engine is 1.8t AUM thanks in advance.

[Bfstrachan]

Just had 6 months trying to get to the bottom of something sounding similar to yours. I had the same symptoms, feeling under-powered and cutting into kinda limp mode. I changed over most of the valves, N75 being the most obvious, but no joy. I also changed all my engine pipework in case it was a boost leak - but still didn't get to the bottom of the issue. Read on a thread about the fuel pump starting to fail and the problems relating to that. Ordered a new complete pump/sender unit and fitted it last week. Instantly I knew things were back to normal! Might be worth a look? My cold starts were an indicator. but that didn't manifest till about 3 months in. On a cold morning it would maybe take 2-3 turns of the key instead of the usual first time start. Also, when I would accelerate gently the engine would be fine, but if i tried to accelerate hard the engine would cut into limp mode. Hope this helps...

[Bfstrachan]

Oh, and mine is an AUM engine too...

[lee1989]

ok cheers mate never thought about that will have a look 

[lee1989]

Not sure if it helps but noticed that it happens more in second gear between 2-3 thousand revs

[Dalo Harkin]

Have you checked all your boost pipes?

[brewey]

Standard DV? If so I reckons the diaphragm could well have split.

[lee1989]

Had a little look at the boost pipes but couldnt see anything wrong with them, it was dark when i looked so will be checking them over properly on sunday when im not in work, and no no a standard dv, it has a forge 007p on there cheers

[Dalo Harkin]

if you do have a boost leak, you will see oil on/near the pipes.
It could be a number of things, have you checked with VAGCOM or a reader for errors?

[Wazzzer]

Don't just go about replacing sensors as you'll end spending hundreds and the fix could be as simple as a split hose. Speaking of which check the breather hose under the engine cover on the right hand side (as you look into the engine bay) of the cam cover, they are renowned for splitting and causing running issues on the AUM / AUQ