Golf GTI 1.8T (AUM)

Problem 1. Lack of power throughout the range, sometime there but more than often like a standard 1.8. Some hesitation and stuttering on idle and when running, feels like its pulling sometimes when I am driving it. The engine management light keeps coming on, VAG-Com gave the following on 2 separate occasions spaced over a month;

April 2 Faults Found: 17545 - Fuel Trim: Bank 1 (Add): System too Lean P1137 - 35-00 - - 17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!) P1297 - 35-00 - -

May 2 Faults Found: 17545 - Fuel Trim: Bank 1 (Add): System too Rich P1137 - 35-00 - - 17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!) P1297 - 35-00 - -

Today 1 Fault Found: 17545 - Fuel Trim: Bank 1 (Add): System too Rich P1137 - 35-00 - -

Im a bit confused as to why ive lost a fault but not entirely unhappy? anyone help there?

What ive done? I have changed the MAF (Mass Airflow Meter) for a new one (Pattern part) and replaced the DV (Dump Valve) new Bosch one. I have removed the inlet pipe from the filter air box to the turbo and can see no obvious leaks.

Possible Causes? Leaking pipe somewhere on the intake system between the airflow and Turbo? Possible faulty MAF, faulty DumpValve or Lambda (O2) Sensor front or rear or both

I have been into a local garage and am fast becoming a DIY expert but that’s probably a bad thing as I am starting to convince myself the problem is to do with all sorts now, so I open my arms in the hope one of you can help me; what I need are possible causes and where to look for the fix; things like which pipes to check etc as I am really struggling and would love to avoid a VW dealer experience

All help is appreciated

Phil

Hi Phil,

I too am having the same problem. Did you manage to sort it out. If so could you kindly tell me how to get it fixed. No garage can seam to sort it out??

Many thanks,

Scott Campbell

Hi Scott,

Ok so here goes…. I’m actually having a go this weekend but here is what ive found so far.

Basically this is 1 or all of 5 things, no more, no less! Ive used a VAG come unit (Laptop and cable) to get the fault codes and lots or internet research to avoid trips to garages although ive been to a few who said (as air whistled through their teeth) No mate could be anything that!!

1. Faulty MAF - This has been changed on mine, best way to see if its this is run it with it disconnected i.e. disconnect the electrical connector but leave the unit in place. Run the car as normal! If there is no or little difference its unlikely to be your MAF. This is the unit that runs between your airlifter box and turbo (FYI this is not your intake pipe as I thought for ages!) it’s about 4-5 inches in size and has an electrical connector plugged into it, the connector comes out but pushing the little plastic clip down, not pulling it up!! Cost about £30 ‘ish’

2. Faulty DV (Dump Valve) changed this as its a possible cause and for £10-£15 its a no-brainer if it was the fault, it wasn’t but its looks newer so hey :-) This is the little black circular unit at the back right of the engine on top under the engine cover, it has 3 pipes into it and it about 2 inches in size. Plus on this a lot of people use Baileys dump valves to hear the cool noise, that’s very bad on the 1.8T's as these engines need to keep the Turbo pressure to work properly not let the pressure out to make cool noises, so if yours goes Wooooshhhhh as your change gear its either fooked anyway or your have a non-standard valve on, i would change it for an original DV as they are pretty good from what i have researched.

3. Faulty N75 Valve, maybe but it’s least likely of the causes from my research! This is a small 1" in size valve with 3 small pipes going into it and is located near the Dump Valve.

4. Faulty Lambda sensor(s) Before and just after the Catalytic Converter are 2 sensors, both tell the ECU (Car Brain) how much of each gas is in the exhaust, the front one, i.e. the one before the Cat is likely to go faulty telling the ECU to adjust the fueling to compensate for a non-existent problem such as over fueling hence it starts to over or under fuel and goes beyond the set tolerance values and trips the light on your dash :( this is highly likely as a cause. They cost £120ish each, you should replace them both at the same time but you would probably get away with replacing the front one only. Easy (ish) to do yourself if you can get to it as it’s just a screw type unit screwed into the exhaust before the CAT and that connects by a wire to the ECU. My advice if it is this is DONT buy cheap, I know VAG are expensive but EBay is not always your friend here!! That’s my advice!

5. the most likely cause is a Boost leak; this took me ages to get my head around so here is my understanding. You have 2 pipes going to the turbo on your engine, one from the intercooler on the front of the car and one from the air intake box. The one you need to look at is the intercooler one and the associated small pipes that feed off it, these are the most likely cause as if they leak the system tries to compensate for the loss in pressure and the outcome is lack of power etc and the codes in this post. It’s a bitch of a job but that’s why most garages can’t be arsed with it. Patience and lots of tea; I’m planning on taking the intake manifold apart this weekend, nothing I don’t have to, only what I need to do in order to check the pipes, then onto the main pipes between Intercooler and turbo and hope to find something obvious although a boost leak can sometimes only show up when its under pressure which can only be achieved on a rolling road as you cant boost by revving it! L  

If anyone can add to this please do as this is my non expert DIY Phil opinion only although it is based on heaps of research and swearing at the car!!

Cheers and hope this all helps!

Phil (Feeling the credit crunch in my fuel bill) :-(

 Hi Phil,

WOW!! You certainly have done your research!! How did it go this weekend? From your options i reckon mine will be the last one as my problem is very intermitent. As my friend owns a garage he has reset the codes a couple of times and it does not come back on for a few weeks or sometimes even months. The only time it seems to appear is after a stretch on the motorway which im guessing is highly likely to be a boost leak??

Thanks for all your help on this.

Scott

Got this off a fellow 'mivver' which might help... similar so worth adding to the list!! Also ive got mine booked into a VW specialist in 2 weeks so ill let you know what thay find.. ive given up loosing weekends on it... just going to bite the bullet..

Hi Phil,

Don't know if you've sorted this yet but I've just had my Audi A3 1.8T (AUM) in to my local independent VW/Audi specialists with the same kind of symptoms and their diagnostic came up with the same 2 fault codes:

17705 - P1297 - 035

Connection charger-throttle valve

Pressure drop

17545 - P1137 - 035

Long term fuel trim add. Fuel, bank1

System too rich

Sporadic

Apparently this is a common problem and it means the throttle body needs cleaning - so they stripped, cleaned and reset it for £50, which I think was well worth it. Running great now!

More evidence to support this at

.

Hi there I own a mk4 gti turbo and had lack of power on accelaration and start up from cold, this would only occur for about 30 secs or so and it would then clear and be fine, I read all the forums and found there could be numerous causes, I decided to use a dtc fault code reader and got the

17705 pressure drop  Connection charger-throttle valve.

I decided after a week or so that i did not know enough about the car and so took it to the vw dealers .

The fault was that the throttle body housing had built up with a carbon deposit and needed cleaning, They also did some adjustment to the throttle angle.

They charged me £60 and the car has never ran better

Just to let you know that i dont think this is a diy job as they have to re adapt the throttle body housing when refitting it to the engine (i dont understand why this is but this is what they told me so i dont reccommend doing this yourself) but this is most likely to be the fix for the 17705 code.

I hope this has been of some help

cheers

GAZZA

If anyone else wants the cleaning / reset doing and you can travel to me I'll do it for *free* - it's only 30 mins of a job

Hi Phil,

Great write-up on possible causes for the 17705 - thanks! I have an Audi TT and have been suffering the same codes as yourself - did you ever get these codes sorted?

I replaced the MAF, DV and checked for leaks but no joy :-( The two codes seem to be related, with the 17705 itself not tripping the CEL, that only happens when the 17545 kicks in as well.

Also, huge thanks to 'Pat' as well - I read his excellent post on the same issue and he was an inspiration to me in trying to get these damn codes sorted! Is yours finally fixed then, Pat? Hope it is!

Many thanks in advance.

LP

Hi LP

Ive concluded that the codes i have been getting could be caused by one or all of the following'

1.   Faulty MAF Sensor

2.   Faulty N75

3.   Faulty Lambda sensors, 1 or both!

4.   Leaking vacum hose somewhere on or around the inlet manifold

5.   Faulty Valve somewhere on the inlet manifold / turbo vacum hose system

I took my Golf to a local garage and hit gold with a mechanic who i swear looked 16 years old but knew his stuff, he rummaged about the engine and said "yeah mate its that there" pointing to a vacum hose valve, he changed it and its sweet, so far!! I think it’s was the PCValve that he replaced and so far so good!! But it could easily have been something else or all of the above!

I have spent month trying to track this down but i bit the bullet and found a VW specialist who gave a crap about what i was saying and listened to me and im very impressed, so impressed here is the website details - http://www.bullenbrothers.co.uk/

I was very pleased, well unless the light comes back on in which case ill delete this post ;-)

Hope this help, Phil.

Thanks for getting back to me, Phil - very grateful for the response!

I'm chuffed for you that you managed to resolve the 17705 issue with your car! From my own research on the code, it really seems to be the 'Achilles Heal' of the 1.8T engine, affecting VW, Audi, Skoda and Seat varients of the engine. I've had it for about 8 months now and have had a load of different people take a look at it without success. :-(

When you say the PCValve, you don't by any chance mean the 'Suction Pump' piping that's located under the intake manifold? It looks kinda wedge shaped - I'll try get an image up later if I can find one.

Anyway, thanks again for your reply and congrats on getting your car sorted! :-) 

 Hi and thanks for the thanks If the light stays off for more than 2 weeks ill consider it a success When i was talking to the mechanic on the phone he said it was a valve under the inlet manifold that had 3 pipes going into it and it was leaking oil, the only one i know that has 3 pipes and is connected in any way to the engine (oil bit) is the PCValve which is this one -

 http://philharris.co.uk/images/Vacuum.jpg

Number 27 on that diagram. I found the diagram on this forum but i havent got a clue who uploaded it, i remember the post was detailed and superb so all credit to that person, if anyone knows who i would appreciate you letting me know so i can credit them for the image? or take it down if they want me to?

I hope you get yours fixed, one the way to see if this valve is busted is to identify it and see if it looks like its been leaking oil? cost me £90 to get it fitted although im sure i could have done it myself if i had known, item itself cost £17ish.

Good luck fellow Vag'er Phil

Thanks again, Phil - very nice image of the 1.8T engine bay!!

I found that link showing the valve I thought you meant:

http://forums.vwvortex.com/zerothread?id=2725794&page=1

I remember looking under the intake manifold on my car a few months back whilst I was checking out the N249 and seen the above item and it was covered in oil. I'm thinking now that maybe I should have changed it out back then, just to at least take it out of the equation. From what people are saying in that post, it seems to control some boost elements and therefore could possibly trip a 17705?

Anyway, I'm sure you've finally sorted your code woes out, Phil and I'm really happy that you beat the dreaded 17705!! Happy and safe driving and thanks again for all your assistance!!

Howsit dude

I mite be reading this post a lil bit late, im from south africa and own a Gti 1.8 t 20 valve mk4, we have recently replaced the motor whihc was all good and sunshine, obviously it handled better thatn the previous one, althoug eventualy my battary had died...

so firstly before the bat passed on soon after the moter was replaced it started picking up a little vibration whilst accelerating and some loss of power. it also starte surging at some points and a lot of low rpm backdiring and also at times hi rpm...another thing i did, i had a dumpvalve fitted on the pipe from the intercooler into the throttle body, with the vacume sourcing from a pipe right of the oil stic below a small cover...and the factory DV is blocked off. so....we replaced the battery, the car was flying faster than chuck noriss's puches, i was shocekd, boost was HUGE the vibration was gone and so the backfiiring, so asued the ecu was reset...but bout a week after this degraded and the vibration thing feeling came back and underperformed again....i disconnected the bat a couple of times but o improvement...

any answers? please...