Golf mk1v aum 1.8t boost on/then off and slight misfire at idle

[donno]

Hi All ,

I have a 2003 aum 1.8t stock standard /no mods etc , the car at present is boosting when cold but when it gets up to temperature the car boost sometimes then has no boost.The car also has a very slight misfire at idle.I have changed the temp sender (green one oem) , reset the throttle body , checked every hose and replaced clamps with forge marine clamps , maf , n249 (this help abit)  and lastly the air pump hoses.

Still no joy and no fault codes at all.I have also tried a new oem n75.Still no joy.The weird thing is in the morning when the car is cold the boost is very strong and the car is smooth no jerking below 2000 rpm.

Any help/advice and pointing me in the right direction would be appreciated.Lastly the car was scanned at Tuningwerkes in Croydon and no fault codes , Ruben(very nice helpful chap) also reset the throttle body.

Still no joy.Thanks all from the poison golf owner.

[brewey]

Have you checked that the DV is holding strong? Not long after I got my gti I had similar problems and it turned out to be a faulty DV. I replaced mine with a forge 008 but if I were to do it again I'd probably save my money and buy the latest revision of the standard 710 valve from the stealers.

[donno]

Hi Brewey ,

Thanks for the reply , I have a forge 008p in my box of parts.I will try the valve and report back.

cheers Donno

[brewey]

Take the one on the car off. Push the piston up with your finger and them before releasing it cover the nipple on the top. When you let go of the piston it shouldn't move. If it does it's knackered (or you've tested it wrong).

But if you have a 008 anyway put it on.

[Dgold180]

Could be a lambda sensor giving the engine false readings when hot, is the car firing up any codes? i had a car that did the exact same and it turned out to be the 2nd lambda sensor (after cat).

[Wazzzer]

Have you tried moving the coil packs around to see if it moves the misfire to another cylinder?

VAG COM has a misfire counter which can be used to find out when the the misfire is happening and what cylinder it is. It might be worth seeing if you're entitled to a coil pack replacement from you local dealers if it hasn't already been done

[Dalo Harkin]

If its a misfire, as Wazzzer has said you need to looking at the coil packs or the spark plugs, the MAF can also contribute to a misfire so try unplugging it and see if the car feels better.

[donno]

Hi All ,

Been awhile a ,I have some good news and bad news.Firstly I checked the secondary air pump and found the rivets had all come loose , leaving large gaps for air to escape.I followed the guide and drilled the rivets and replaced the rivets with bolts and nylock nuts.I also replaced the spark plugs.This helped stop the bad idleing and help the car not have the hoover noise at start up.The car drives a bit smoother.I then took of the EGR valve that sits on the side of number four piston.The valve was seized and carboned up beyond belief.The gaskets were also leaking.The car has improved again since replacing the EGR valve(shut off/combi valve).

But now for the bad news , The car still boost strong then nothing and still is jerky especially in first gear when you put your foot on the gas initially.The boost is on then off the very strong then off.I have also replaced all the coil packs under the recall.Their is no fault codes coming up at all.

Any help will be very much appreciated.Oh lastly I have bought a new PCV valve(genuine part) and t piece , I will fit this on Tuesday.Very Very frustrating.

Help please.Love the car , hate the problems

Cheers Donno