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Model specific boards => Golf mk4 => Topic started by: lee1989 on 24 January 2015, 17:01
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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.
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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...
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Oh, and mine is an AUM engine too...
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ok cheers mate never thought about that will have a look :smiley:
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Not sure if it helps but noticed that it happens more in second gear between 2-3 thousand revs
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Have you checked all your boost pipes?
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Standard DV? If so I reckons the diaphragm could well have split.
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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
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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?
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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
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Ok thanks will be checking all pipes tomorrow, and yea its been scanned again and still no fault codes, thinking of having a smoke test done if i cant find a split, also starting to have another problem which is when im excelerating it will stop excelerating for a couple of seconds and then pull off starting to puzzle me now :sad:
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I personally think you have a boost leak somewhere. just check all the main pipes from the turbo to the intercooler and back up to the throttle body.
Then check all the smaller ones that attach under the inlet manifold / onto the fuel pressure regulator
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I would be getting spray bottle of soapy water, let the car idle and spray all the hoses and look for bubbling.
I had issue, could not find any leaks via my degrading eye sight and low and behold, spraying it, I picked on up at least 2 leaks that I checked and thought were fine.
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Finally got time off work to have a look at the car but still struggling to find out whats wrong with it :angry: sprayed and checked all pipes cant see any splits in them, changed the n75 valve again but still not solved it,
Under throttle it seems to loose ALL boost for a couple of seconds and the will pick back :huh: what else could this be as im out of ideas now any help much appreciated thanks
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have you cheacked the maf
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clean the throttle body
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i had same problem i changed the maf and the coolent senor as both showed up but still had bad idle, then checked plugs and had slight bit of oil in there and decided to change rocker cover gasket and on removal of rocker cover the gasket was rotted to the core, replaced gasket on friday and since then engine has been running fine might be wurth a look?