Heavy fuel consumption Golf GTI Mk4 1.8T

[MrGolf123]

Hi, New to the site, from browsing though seems you guys know your Golfs so hopefully you can offer some advice on my problem:

I've got a MK4 GTI 1.8T - its using too much fuel - getting about 32/33 at 70 on motorway and around 24/25 around town, stop/start etc. Its been in and out of a local German Specialists who's had it diagnosed a few times and has so far done the following:

Changed the Air Temp Sensor
Cleaned the Throttle head
Changed the AMM

The thing is, it drives OK, and now I'm starting to think I'm going mad and am imagining things cos its been like this for about 2 months, but I'm sure it was much better on fuel than this? Someone has suggested the recirculating dump valve which I had a bit of a problem with cos when I got it, it had an aftermarket DV on so I took it off and put the original one (which the guy gave me with the car - back on) If the recirculating dump valve is faulty - could it cause these kind of issues?

Any feedback or help would be great

Thanks

Frustrated and very Skint Golf Owner!

[Crasher]

My Octavia VRS (virtually the same engine and car under the skin) returns 23 around town and 35 on the motorway.

[MrGolf123]

Thanks mate, really? That just seems really low? and I'm sure it wasn't like that when I first got it? Its due a service though, could that have any effect? Meant to say that thats based on me really nursing it too - not driving it as I would like to!

In response to your "People who work sitting down" post - I pulled twice as much as I do now when I was a brickie - just a shame the missus and the local got most of it!

[Crasher]

My signature isn't strictly true but it just appealed to me. A service shouldn't show up any more reasons for high consumption than a fault code read. What year and engine code is your car?

[MrGolf123]

Its a 2001 51 plate - not sure of the engine code? where would I find that? Thanks for your help with this.

[Eshrules]

this 'local German Specialists ' you speak of... have they, at any time, given you a printout of these fault reading sessions?

i fear that someone may be taking advantage of your relative ignorance (excuse the bluntness, i struggle to find another phrase)

IMHO, the economy you're returning sounds about right for a 1.8t, it certainly isn't low.

for example, my Tdi 115 returns on average around 25/30mpg (at the moment, with the cold weather) and around 45/50 on the m.way. so to say you're getting 25mpg out of a 1.8t really isn't that bad IMO

if you're local, you're more than welcome to drop around for a fault read, just as a precaution :)

[MrGolf123]

I'm based in Manchester - don't know where you are? Yeah, I have the print outs, I've left them at home though so I'll post them later on - one was about a loss of pressure to the throttle valve - can't remember the other - think it was about the ECU - which is when they told me to change the AMM.

Have spent £600 chasing this round now and no better off!

[Crasher]

The engine code is on the cam belt cover, the data sticker in the boot and on the data sticker in the inside front cover of the service book. It will be ARZ or AUM.

[Nicks]

yo!

I've a 1.8t golf 03 plate and it does average 32/34mpg if I'm not bootin it and around town about 28 but my town isn't very big so I'm in out if ya get me..

I did hear that older dump valves can mess up your ecu but don't quote me on that.. better ask crasher!

alright crasher!

[Crasher]

Mine is remapped to 220PS and with an APR R1 diverter valve and K&N panel filter, but that is all. It has surprised me how poor the consumption is around town but everything on the car is 100% such as new VAG engine, turbo, intercooler and every sensor. It runs nearly perfectly (I am still trying to trace a slight pulsation in the power delivery but customers cars keep getting in the way) and generates no fault codes and the emissions are perfect. If the emissions or fueling were out even slightly on a Golf 4 GTI with an AUM engine, the "check engine" light would come on.

[a8 tech]

I have a vrs 1.8 t and have also had two 1.8t mark 4 golfs and your fuel consumption is normal.The golfs would do 400 miles to a full tank and the vrs does 350 miles,i have been doing the same route for 5 years.When i went cornwall i found 42mpg was average which is fantastic.

[MrGolf123]

Yeah, meant to say that actually, had it all checked for emissions etc - spot on, been told its not the Lambda sensor?

To answer earlier questions on this - these are are codes I've been told was reading out with before the AMM was replaced - not had it checked since, I'm saving up!!!

P1200 - Exhaust supercharger air circulation valve

Crasher - to answer your question about the code on my car - its AUM - do you need the rest of it?

Thanks for all your help guys

[Crasher]

I thought it would be AUM, which is the later spec. The fault code you had does not indicate a fault MAF/AMM, it means either the throttle body is dirty and needs readapting to the ECU or the turbo diverter valve is faulty, both of which are very common problems but simple to put right.

[MrGolf123]

Thanks for that Crasher, I'll have to go back to where they did the MAF and speak to them again (hopefully - they'll clean the throttle body for nothing seen as I've spent a fortune with them already - I'm guessing its not a huge job?) Failing that then I'll have to look at the Turbo Diverter Valve - what do you reckon the damage on that would be? Just want to make sure I don't spend more money unnecessarily.

Thanks for your help with this - I'll try that and let you know how I go

[Eshrules]

Thanks for that Crasher, I'll have to go back to where they did the MAF and speak to them again (hopefully - they'll clean the throttle body for nothing seen as I've spent a fortune with them already - I'm guessing its not a huge job?) Failing that then I'll have to look at the Turbo Diverter Valve - what do you reckon the damage on that would be? Just want to make sure I don't spend more money unnecessarily.

Thanks for your help with this - I'll try that and let you know how I go

to be honest, listening to how this garage have conducted themselves, they seem to be taking you for a run with your money.

i really would consider changing garage.

the other point i want to make is... is there actually anything wrong with the car? the fault they read could have been historic, in that it may not be a current fault. what they ought to have done is fault read the car,clear the faults, take it for a test cycle and then read again, THEN act on the faults logged, if any were found.

to be honest, it sounds as if your car is just fine to me, the emissions are good and it doesnt sound as though you're having any actual running issues.

im based in manchester, copley/stalybridge area, drop me a PM if you want to bring it round for a scan, im free most saturdays between 9 and 12 anyway.

[Crasher]

Don't hound them too much, it is almost standard procedure to change a MAF these days when you have a quirky no code running problem, they are so unreliable. You should pay about £60 for a throttle body clean and re-adaptation. A genuine diverter valve (06A 145 710 A) is only £24.95 and takes minuets to fit but you need two pipe clips (N 102 581 01) at £1.52 each. If you give them grief about getting it wrong previously and push for free work, it is highly likely that the work will get done to a good standard and then it may not work which will confuse the situation even more as you will think the job has been done. Cleaning the throttle body takes time, care and patience to do it properly and to void damaging a very expensive (£341.95) part; they are very easy to scratch internally which can ruin them.

[Eshrules]

Don't hound them too much, it is almost standard procedure to change a MAF these days when you have a quirky no code running problem, they are so unreliable. You should pay about £60 for a throttle body clean and re-adaptation. A genuine diverter valve (06A 145 710 A) is only £24.95 and takes minuets to fit but you need two pipe clips (N 102 581 01) at £1.52 each. If you give them grief about getting it wrong previously and push for free work, it is highly likely that the work will get done to a good standard and then it may not work which will confuse the situation even more as you will think the job has been done. Cleaning the throttle body takes time, care and patience to do it properly and to void damaging a very expensive (£341.95) part; they are very easy to scratch internally which can ruin them.


would you say the TB has anything to do with this crasher?

(not questioning here....) i always thought that TB faults would cause things like poor acceleration or loss of power/poor idle?

also, i'm not actually that clued up to the workings of them, so apologise in advance for my show of ignorance, but if the Dump valve has been changed, should the TB not have been re-adapted/aligned after that?

[Crasher]

It’s a perfectly reasonable question. “P1200 VAG 17608 Recirculation valve for turbocharger-N249-, mechanical malfunction” can mean the Diverter Valve is faulty but also that the throttle body is dirty and incorrectly aligned. When you back off the throttle, the ECU detects a loss in pressure and assumes this is the DV when in fact it is air leaking past the throttle plate. VAG-COM also partly incorrectly adds its own comment to this fault code in relation to the DV.

[MrGolf123]

Thanks for your help with this guys, understand what you're saying Crasher - could really do without causing more problems in that area. Eshrules, if its OK, I can bring it up to you on Saturday? I'm not too far away - live in Stockport. Would really appreciate someone else having a look at this and seeing what you think? Whats a PM?

Cheers

[Eshrules]

Thanks for your help with this guys, understand what you're saying Crasher - could really do without causing more problems in that area. Eshrules, if its OK, I can bring it up to you on Saturday? I'm not too far away - live in Stockport. Would really appreciate someone else having a look at this and seeing what you think? Whats a PM?

Cheers

a PM is a private message ;)

but with less than 10 posts, i dont think you can send any. i can only offer my opinion, Crasher knows his stuff and a lot better than i do with regards to this area. i can fault read it and give you any fault codes i find, but what you do after that is your choice mate ;)

saturday is fine, earlier is better than later tbh.

[MrGolf123]

Nope - don't think I can do private messages. I'd really appreciate your feedback anyway, before I go back to the place I've been taking it to before.

Anytime on Saturday is fine - do you want to send me address info?

Thanks

[nick5golfs]

Just to confirm what the others have said re fuel economy. I have had 5 Turbos and all did 25 odd in town and 35 odd on motorway. Less if a drove them fast.

Only time it was bad was when a lambda probe went but your engine managemnet light should come on if that happens.

Cheers

[MrGolf123]

Thanks for your feedback Nick - I'm beginning to feel like my Golf used to be hydro-power or something! I swear that when I got it in May I was getting 37/38 mpg when doing 80/85 on the motorway and no less than 30/32 around town? Maybe I'm imagining things - however its giving a fault code still? very confusing and frustrating.

[Aaron-Golf]

Hi guys,


Im also havin Very Low fuel consumption, 18-23mpg around town. its due a service which is booked in for 18th dec but been told the it wont make too much diff but a little none the less. I only got the car two weeks ago but its been mentioned abt the cat convertor might need replacing, will this make any diff??

Thanks in advance

ps my car is a gti 2.0 115 bhp.

[Crasher]

Cats on the 2.0L only fail due to other common problems on that engine such as air leaks, AMM, leads, plugs, coil pack and lambda sensor.

[MrGolf123]

Crasher, I've done this not - had the diverter value replaced with a VAG one as per the code you gave me but theres still no improvement, I did ask them to clean the throttle body as you said but looking at what they charged me £50 inc VAT) I dare say they didn't.

Any more ideas? - still the same problem, heavy on fuel and just a bit lacking on power. Also, can I just ask, at what RPM in the turbo supposed to start? I'm sure i can hear/feel mine at around 1500 rpm?

[Crasher]

OK, let’s start at the beginning as this thread is jumping around a bit. What year and engine code and are there any fault codes stored? Has it been re-mapped? £50 is a little cheap for a throttle body clean and reset but only by a few pounds.

[MrGolf123]

Its a 51 plate 1.8T Standard 150bhp - engine code is AUM. It was coming up with a fault code of "P1200 - Exhaust supercharger air circulation valve" - which you said sounded like either the throttle body or the diverter valve. I've changed the diverter valve - I gave them the code for that (06A 145 710 A) which you gave me and told them to clean the throttle body but like I said - £50 inc VAT for a new diverter valve fitted and a throttle body clean is too cheap isn't it?

Whats your take on the Turbo kick in question? I'm sure it starts at 1500rpm - is that right? I thought it should be 2000rpm when the turbo starts?

Thanks for your help by the way

[Crasher]

OK, £50 all in is way too cheap, I charge £60 to remove and clean the TB with a reset after, never mind the valve at £25 plus clips and fitting. I messed up the part number for the valve it should be 06A 145 710 N but as 06A 145 710 A doesn’t exit, I imagine they fitted the right part. The turbo starting to spool up at 1500rpm sounds rather low and leads me to suspect a device known as the N75 valve which may be jammed closed and this would lead to over boost. Mine jammed open and under boosted. I feel that the TB will still need to be removed, cleaned and reset; I bet they didn’t appreciate how important the cleaning procedure is and just gave it a quick wipe out whilst still fitted and probably didn’t re-adapt it. Have you a decent VW specialist near you? If not, you may have to take it to VW for this.

[MrGolf123]

Right, well i thought I had a good independent specialist near me (they've worked on a few of my friends Golfs/A3's but after spending £150 in diagnostics and £160 changing the Air Temp Sensor and AMM I'm starting to think that they're not as clue up as I thought. The Diverter Value and supposed clean of the TB was just done by a local guy who I know through my Dad, so that leads me to think he just wiped it as you said. Another question, sorry! Once he'd fitted the new Diverter Value - did he need to reset/readapt anything or is it just a case of stick it on and away you go?

[Crasher]

The diverter valve is a plug and play affair but the TB needs to be adapted after cleaning.

[MrGolf123]

Right - well I guess I'll try and get the TB cleaned again then - don't suppose you know of any decent VW specialists around Manchester do you? Failing that I'll have to go to my local dealer like you said.

Thanks for your help with this mate - appreciated