low mpg mk4 golf gt tdi

[tetskoma]

Hi, I wonder if you could help me.

I just bought my first golf mk4 gt tdi (115bhp, 2001). It is a really nice car! However, it is not so economical as I expected. I often drive my friend's Golf Gt tdi (130bhp 03 reg), and it easily returns around 50mpg, even when driving around 80mph.

But my poor one returns only 43mpg maximum with really careful driving at 65-70mph on motorway. If I am not careful, even I wouldn't get 40's.

I know this is a common topic, so I did a little bit of research myself. I found MAF should be changed. Yesterday, I bought a new MAF from GSF (cost only £30!!), and fitted (easier than I thought) no problem!

The result is.......very good in terms of performance:approve: but it doesn't improve MPG at all:(. The car drives much smoother and stronger than before. I used to have a flat spot between 2200rpm and 2350rmp (lose the power significantly), but now it has gone, and revs really nicely!! Hence, I don't have to accelerate hard now, which should bring down my fuel consumption even more. However, it doesn't at all.

Today, I drove about 1 hour on M23 and M25 at 60-65mph constantly. I managed to get 43mpg. For the first 30 mins, I thought it didn't reach even 40mpg. I am really disappointed with this low mpg. Would anyone help me to solve the problem please. Thank you.

[FLENG2008]

checkt the basic's, tyre pressure, breaks binding etc..

[tony19]

when was the last time it had service donne to it?
if not sure do one.

[tetskoma]

A happy new year! Thanks for your replies.

As far as I know, a full service done in September, and it had MOT in October. From the record of MOT, I can see they replaced quite a few bits and pieces.

Brakes works fine. I cannot feel anything wrong. I am not sure about tyre pressure because it has got a diffrent set of 17 inch alloys. But again, they don't look particularly low or high. This may affect mpg slightly. I am looking for standard 16inch alloys actually. The ride is a bit too hard with these alloys.

Aprart from this bad fuel econmy, the car is brilliant. I don't have to push hard at all as it goes quite quick with even slow acceleration. I've been trying to drive in different ways to find out most economical driving. Maybe I change gears too early (around 1600rpm-1800rpm unless if I need to go quicker).

I am thinking of getting it serviced soon (inc cam belt). Does anyone have got any more ideas what I should check to fix it? I am not expecting 60mpg or something like that. I would be very happy if I can get around 50mpg at 70mph on mortorway, and around 40mpg around town drive.

Thanks.

[FLENG2008]

this has been covered a few times before, firstly jack up the car and see if the wheels spin freely, and im not sure if you can check the tyre pressure with your digital eye, so go check these too.. if they do spin freely and pressure ok go and get it plugged in (VAG com.)

[tetskoma]

Thanks for quick reply. Yes, I will ask my garage when I get it serviced (it will be in 2 weeks time).

This morning, just out of my interest, I plugged off the connector from MAF and drove it about 10 mins or so. To be honest, I couldn't feel much difference. Does it mean my new MAF isn't functional? But it is very obvious that the car (withe new MAF plugged) is running much better than before I replaced the old one.

Regarding VAG com, do I have to go to VW dealer? I still need to check wiht the garage I use, but I think he has got some computer equipment to plug in. I will see how it goes.

Thank you very much.

[speed12]

What size are your tyres with the 17's? I assume they are 225/45 and are most likely wider than the standard 16s.

I used to get about 50mpg in my bora with the standard 16 inch wheels and tyres, since upgrading to 17 inch with a wider tread I have seen a significant drop in MPG, i struggle to get 45mpg these days, though I have noticed the trip computer is consistantly low.

Are you going by your trip computer or working it out the old fashioned way? In my last tank of fuel the trip computer said I got 41mpg, working it from receipts I got 47mpg...

[tetskoma]

Thanks for your reply. You are spot on. I just checked the size of my tyres and you are right.

Now I am convinced that I should get anohter set of alloys in 16inch or 15inch. I am not that fussy about the styling, so I will get vw standard 16 alloys from ebay or somewhere. My 17 alloys - I don't know which make it is but quite cool and I know it cost the previous owner 924 pounds from the receipt.

As it is still in a good condition, I am sure I can sell it to someone to cover the cost of 16inch alloys.

Thank you very much for your advice.

[FLENG2008]

Thanks for your reply. You are spot on. I just checked the size of my tyres and you are right.

Now I am convinced that I should get anohter set of alloys in 16inch or 15inch. I am not that fussy about the styling, so I will get vw standard 16 alloys from ebay or somewhere. My 17 alloys - I don't know which make it is but quite cool and I know it cost the previous owner 924 pounds from the receipt.

As it is still in a good condition, I am sure I can sell it to someone to cover the cost of 16inch alloys.

Thank you very much for your advice.


i have a set of 18's, and i can do 50mpg average when doing 70-90mph on a trip ,in my opinion i dont think its the wheels sorry....

[speed12]

Yeah, I dont think you should buy a set of wheels just yet.

Is there someone you could borrow a set from? just to try it?

It has definately made a difference with my car, I dont care what people say. When I had to have an alloy repaired i put my old ones back on and sure enough the average mpg for that tank was about 50mpg again.

Like I say, see if you can borrow a set for a week or so before committing to buy!

Dont want you wasting your money on something that may or may not have an effect.

Of course with mine it could be the make of tyre as well as the size. Also theoretically the width of the tyre will make a difference as it will increase rolling resistance, My 17 inch alloya are also pretty heavy which is not good.

[iworld]

Hi

It seems that you are trying to be gentle with your right foot to achieve better mpg's - i would check the following

Tyres pressures - check for consistency
Has it been regualarly serviced? Oil filter
Check Air mass meter
MAP sensor - cheap to replace
Get the vehicle under a diagnostic machine
Could also be a fuel sensor - which i had to chnage on mine - i dont know it that is the exact name

hope it works out!

[tetskoma]

Thank all of you for giving me your opinions truely based on your experiences.

Well, I agree I should try to borrow a set of alloys from my friend first. FLENG2008 - your car is amazing - it can still return around 50 mpg at 70-80mph travel. Actually, my friends Golf gt tdi (130bhp) does the same. That is why I want to do get better mpg from my golf tdi. I will check tyre pressure tomorrow. Maybe I was misinformed about the value of tyre pressure. I looked up on web and it should be more than I was told. I think I set them around 26(? i don't know the unit), but it should be 31-32? or so. But does it make such a difference on mpg? If so, the wheel size should also have a big impact on mpg, as speed12 said.

Yes, I am trying to be very gently with my right foot. The problem is that the accelaration is too slow when getting out of roundabout or after stopping the trafic right etc. I would often nearly get hit by the car behind. But if I try to go with decent speed, the mpg drops significantly (I am not doing a boy racer).

For example, if I drive from my office in Essex to my home in Sussex, it is mainly on motorway about 1 hour journey. I drive about 1 mile (actually only a few mins) till I reach non-stop contstant 65-70mph driving on motorway. I have two roundabouts between. If I accerate hard (normally?) before I get to motorway, I wouldn't even get 40mpg during the first half an hour drive.

Anyway, I will get it serviced soon and will check every single point you gave me. Thank you very much for your help and advice. I will keep informing here how it goes.

[FLENG2008]

thank All Of You For Giving Me Your Opinions Truely Based On Your Experiences.

Well, I Agree I Should Try To Borrow A Set Of Alloys From My Friend First. Fleng2008 - Your Car Is Amazing - It Can Still Return Around 50 Mpg At 70-80mph Travel. Actually, My Friends Golf Gt Tdi (130bhp) Does The Same. That Is Why I Want To Do Get Better Mpg From My Golf Tdi. I Will Check Tyre Pressure Tomorrow. Maybe I Was Misinformed About The Value Of Tyre Pressure. I Looked Up On Web And It Should Be More Than I Was Told. I Think I Set Them Around 26(? I Don't Know The Unit), But It Should Be 31-32? Or So. But Does It Make Such A Difference On Mpg? If So, The Wheel Size Should Also Have A Big Impact On Mpg, As Speed12 Said.

Yes, I Am Trying To Be Very Gently With My Right Foot. The Problem Is That The Accelaration Is Too Slow When Getting Out Of Roundabout Or After Stopping The Trafic Right Etc. I Would Often Nearly Get Hit By The Car Behind. But If I Try To Go With Decent Speed, The Mpg Drops Significantly (i Am Not Doing A Boy Racer).

For Example, If I Drive From My Office In Essex To My Home In Sussex, It Is Mainly On Motorway About 1 Hour Journey. I Drive About 1 Mile (actually Only A Few Mins) Till I Reach Non-stop Contstant 65-70mph Driving On Motorway. I Have Two Roundabouts Between. If I Accerate Hard (normally?) Before I Get To Motorway, I Wouldn't Even Get 40mpg During The First Half An Hour Drive.

Anyway, I Will Get It Serviced Soon And Will Check Every Single Point You Gave Me. Thank You Very Much For Your Help And Advice. I Will Keep Informing Here How It Goes.


26 Psi Is A Bit Low, I Put 30-32 In Mine

Is Your Deff A Gtdi Cause My Missis Has Got A A4 100bhp And That Struggles To Do 45mpg On A Motorway Run....while Mine Will So A Easy 50-55+

[tetskoma]

Hi

I checked the tyre pressure this morning and they were very low actually as I set them around 24-26 last week. I pumped all of them up to 32(psi?). I finished working very early today to pick up someone from Gatwick and went to Brighton about 1hr30mins on motorway. I managed to get 50.6mpg at 65mph all the way from Essex with gentle accelaration. I don't think I would get 50mpg if I go at 70mph, but this is a big improvement for me. Now I know I can save some petrol money if I go a little bit slower. Thank you very much for your advice FLENG2008!! If I sort out some other bits and pieces, maybe my car will do as good as yours:D

I will have the car service in two weeks time and I hope I can tell your more improvements. Thank you.

[veedub76]

Cold weather may be a contributing factor to your low MPG,my car in the last few days has struggled to hit 50mpg but i filled with shell diesel and the mpg has been reduced whereas normally i'd use supermarket diesel.


Do you use millers diesel aditive?If not give it a go and see if it makes a difference.Also may be worth checking airfilter for debris and dirt?Tyre pressures and also you mention you run bigger wheels this may not be helping matters.Also getting it rigged up to VAGCOM may chuck up fault codes if any logged in ECU.

If all else fails give it a damn good thrashing through the gears and see if it makes any difference afterwards!:approve:

[tetskoma]

Thank you very much for your reply.

It's been so cold these days and it takes so long till the engine temp reaches 90 degrees. No wonder if it affects the mpg.

I always use Shell V-power diesel despite the cost. Before having this golf tdi, I always use premium petrol for the cars I used to own and never had a problem with the engine. Therefore, I prefere using premium diesel for my golf. Do you think I should also use some diesel aditive?

Since pumping up the tyre to correct pressure, my mpg has been a little bit better. I got about 42mpg when I went around the town. But it still drops rapidly if I accelerate harder. I have to go slowly...

I will book a full service tomorrow and ask them if they can do VAGCOM check. I hope I can find any problem causing low mpg.

[Yelloperil]

I agree with SPEED12 the bigger wheels can make a difference....

I had 18's on my golf and struggled to get 40mpg's on a run however when i fitted the std 15's off my GF's car i was hitting 48-55mpg on the same route

As regards VAGCOM you dont have to go to a dealer have a look on here or ukmkivs.net they should be someone local to you that has it and will help for a small fee

If your close to derby i could do it.....


if i were you i'd try the following:

1: check brakes for binding
2: Full service
3: Vagcom or other diognostic test for faults

Then try the wheel swap.

[tetskoma]

Thanks for your reply. I have asked my friend to let me use his set of 15 vw alloys. Just don't have time to do it yet. His golf gt tdi 130 (03 reg) easily hits 50mpg even when he is driving at 80-85mpg on motorway. So I still believe the size of the tyre affects my mpg. I will post here when I have tried 15 alloys.

Today, I found the fuel leaking from a small hose by the engine. The car didn't start at all this morning. The battery etc looked fine and I though it was like no fuel. I called RAC rescue and found this fuel leak - dripping quite a lot. Now I know why sometimes I had smell of fuel from the engine (not into the car) when I open the bonnet. Actually, this leaking fuel cause the damage on the coolant hose underneath, which I had to replace last month just after I got the car.

Now RAC fixed it and stopped leaking although I can see very very slight leak from the fuel pump(? which is on the top side of the engine). I didn't realise this as they were covered with the dirty oil leaked long time ago. RAC guy clean around there and we were able to see what was happening there. I haven't tried the car yet since, but I hope this will also help to improve my mpg. I am driving to Essex this eve, so I will let you know how it goes.

I booked a full service which will be in two weeks time. I will check the brake binding then. Also, he said he could do some computer diagnosis for my car. If he cannot, I will take the car to the dealer.

Thank you very much and I will keep informing you here.

[tetskoma]

Hi, I just came back to Essex from Sussex and I managed to get 52.6mpg at 70-75mph most of time on motorway:approve:. It is getting better. Today, I went faster on purpose as I was a bit tired of trying to go slowly although I still had to be very gentle with my right foot on acceleration.

Also, I filled up the tank on the way. I did 509miles over 48.3 litre of diesel. Which works out about 47mpg, I think. MPG (2) on the dash showed about 45.9mpg, so it was better than the figure shown. I lost a lot of fuel when RAC was fixing the fuel hose this morning, and left the car on idle for 30-40min after changing the coolant afterwards today. So taking this into account, I must have done nearly 50mpg total:D (most of time I drove around 60-65mph on motorway).

But I am still aiming to hit 50mpg at 80mph like my friend's golf tdi does. Hopefully, after having a full service and VAGCOM, I want to do better.

Thank all of you for your advice.

[FLENG2008]

im glad you got it sorted, i knew the wheels weren't the problem as i have 18's and still hit 50+mpg

[tetskoma]

Thank you, FLENG2008. Now I know my golf could do better like your wonderful golf does:D.

When I filled up the tank yesterday, I noticed fuel price dropped a lot. If I put V-power diesel (@1.00), it is nealy 20% more expensive than unleaded petrol(@0.80). My golf has to do at least 20% better than my old nissan primera gt (which did about 42mpg (on board computer showed, I don't think this is ture and must be 3-4mpg lower in actual figure) at 75-80mph on motorway). Anyway, I have to do 50mpg at least.

Maybe I should create another topic here, but I would like to know your opinion about premier diesel. Do you think it is worth using it despite the cost?:confused: