Golf GT TDI 150 Overboost issues

[volatilebear]

Hi there,

I am new to all of this so please bear with me. I have just purchased a Golf GT TDI 150 and had it for 4 weeks, after the first 2 weeks I noticed the car went into limp mode and produced black smoke. I was doing 70 on a slight gradient in 4th car then suddenly noticed I was in limp mode with black smoke.

I wanted to get an ECU remap and a diagnostic before to ensure that the car was fit for purpose but was obviously skeptical due to the recent limp mode issue. I did some research and found the R-TECH was one of the best places to go so I went along yesterday for a rolling road.

Nick ran the car through its paces and it brought up overboost and underboost issues. Unfortunately I do not have the original graph but the overboost started at 2300RPM and was at its peak of 3000RPM when power was applied for a good 10 seconds. I have the second graph but not sure if this highlights any relevant information, please see below:



They checked the turbo twice for sticky VNT and they said it seemed unlikely as there was so much play within the Turbo. He narrowed the problem down to most likely being.

1. N75 Valve

2. Vacuum pipes

3. Actuator on the turbo

Obviously I will be thrilled if option 1 and 2 resolve the issue however if its option 3 then everything gets a lot more expensive as a brand new OEM turbo is around £800. I know that there are other "cheaper" alternatives such as a second hand turbo (Nick advised to not get a reconditioned turbo as it will cause more issues than there worth), a failed turbo and remove the potentially working actuator and fit it to my turbo and ive also recently heard of the "Mr Muscle" cleaning method however this may not be an option as I am new to amatuer mechanics and do not have any tools.

I have done some research and it seems a lot of people are recommending VAG-COM software with the ODB2 II 409.1 lead off ebay however because of my lack of knowledge perhaps this is not a good avenue to go down? I know that you can control a lot of the cars characteristics which could potentially be confusing however perhaps for fault finding this is quite easy to use?

I am thinking that my best option would be to just purchase an OEM VW N75 valve, Vacuum pipes, any other small pipes that could be related and going to a rebutable independant VW specialist who won't try and scam me. Additionally, whilst the car is there, I would get an Allard EGR delete kit fitted and replace weeping boost pipes (Nick said weeping boost pipes wouldn't cause the overboost but are most likely faulty and in need of replacement so may as well do it at the same time).

I think the best method for someone like myself would be for me to purchase the cheaper componants OEM from a VW dealer and then to go through an independant VW specialist within my area who has experience with these issues and won't scam me. Additionally, they need to diagnose the car after the work has been carried out or perhaps I need to obtain a VAG-COM and do this myself? I am from the Hertfordshire,can you guys recommend any garages that fit this description, any you have personally had great experience with in perhaps a similar situation?

 Additonally, I need some help with part numbers:

1. N75 Valve - 1K0 906 627A (Have been told its either A or B at the end> - Although I have heard its now this "Its been 1J0906627B and has changed to 1K0906627A in april 2007 apparently." - I have also been told its known as a Pressure Converter to the dealers? - Please advise

2. Vacuum pipes, Boost pipes and any other related pipes Partnumbers/Name - e.g Will the dealer understand what I am referring to if I ask for Vacuum and Boost pipes?

I want to say a big thanks to Nick and the guys at R-TECH for outstanding customer service, I will definitely be returning there once I have resolved my issues!

Thanks for your time and really appreicate any help.

Mark

[old_n07]

Changing the valve is something you can do yourself

It is mounted on the bulk head and easily to get to, the vac pipe can be had off ebay (silicone vac hose) you will need 3mm and 4mm to replace it all, just take a hose off at a time and cut the new peice to length and replace.

If you do need an actuator they can be had for about £65 from a turbo repair specialist although they will need setting up afterwards. You can check the actuator with a hand held vac pump, if it holds vacuum then it is ok

Neil

[Golf_GT_TDI]

I can't help with much of that but I can help with ETKA which confirms part being superceded as you mentioned...

[JimBR]

Midland VW have got a good reputation and would help you out. Your a bit far away though.

[old_n07]

A bit of reading for you:

Sticking VNT FAQ

Vac line simplification this has the valve layouts and connections in it too

Neil

[scarr89]

I have a spare N75 if you need it. I know it works as I bought it to see if mine was knackered and there no difference. Try a known working one before you fork out on a new one.

[old_n07]

Should you need an actuator these can be purchased fro Turbocharger Services near Huddersfield (01484 866671) from speaking to Chris the owner he can get replacement actuators for about £65.

[scarr89]

If you are planning on having it mapped in the future it maybe an option to get a forge one instead, I haven't read too much about them or heard any reviews. But for a bit extra dollar it maybe worth it...

http://www.ebay.co.uk/itm/130555132078?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

[old_n07]

When I was going through the same thing Nick (r-Tech) said at the time that the standard one was fine and he wouldn't necessarily recomend fitting an uprated one when I asked.

[Rhyso]

I tried the Forge Actuator on mine; i did a write up which should be kicking around somewhere.  Basically I wouldnt bother; yes you can change the springs but none where really suited to the boost levels.

I had a standard one fitted in the end