Author Topic: Extremely bad fuel economy MK4 GTI  (Read 2184 times)

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Offline DaffaN

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Extremely bad fuel economy MK4 GTI
« on: August 25, 2020, 12:46:22 am »
I have a stock 5 speed tiptronic mk4 GTI which does horrible gas mileage, im not sure when it started since i got the car used and just never really paid attention until i found out that these cars should be able to do 500-650km on a full tank while mine struggles to go 400km. I knew the previous owner didnt maintain the car properly so can someone give me some pointers on what to check/replace/clean/fix to help with this issue. Its a pain in the ass since im a broke uni student and fuel is really eating up my wallet.

I know aggressive driving doesnt help but honestly i drive like a nana most of the time

Oh and another question, is it necessary to run 95/98 on these cars?

Offline Alfashark

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Re: Extremely bad fuel economy MK4 GTI
« Reply #1 on: August 25, 2020, 02:36:51 am »
At a minimum I'd be looking at the Coolant Temperature Sensor and thermostat - If it's not getting up to running temp or the computer thinks it's not up to running temp, it will run rich and get an appetite for fuel.

95 as a minimum on these too.
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Offline Trofeo

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Re: Extremely bad fuel economy MK4 GTI
« Reply #2 on: August 25, 2020, 08:13:46 am »
Get it scanned. Could be the MAF also.
2015 Amarok 4WD auto
2018 Golf R-Line Tsi

Offline the phantom

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Re: Extremely bad fuel economy MK4 GTI
« Reply #3 on: August 25, 2020, 11:05:52 am »
MAF yes, clean the throttle body, dunno about the turbo, but these are easy at home jobs on a 2.0 atmo
Land Transport New Zealand, taking the fun out of driving since August 2008

Offline DaffaN

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Re: Extremely bad fuel economy MK4 GTI
« Reply #4 on: August 25, 2020, 12:30:47 pm »
At a minimum I'd be looking at the Coolant Temperature Sensor and thermostat - If it's not getting up to running temp or the computer thinks it's not up to running temp, it will run rich and get an appetite for fuel.

95 as a minimum on these too.

I actually just changed the coolant temp sensor since it was reading 90 no matter what when i first got it, ill check out the thermostat, thanks for the advice

Offline DaffaN

  • Posts: 15
Re: Extremely bad fuel economy MK4 GTI
« Reply #5 on: August 25, 2020, 12:33:12 pm »
MAF yes, clean the throttle body, dunno about the turbo, but these are easy at home jobs on a 2.0 atmo

Mines a turbo, i wouldve sold it already if its the 2.0 ahahahah

Get it scanned. Could be the MAF also.

Should i start with a MAF cleaner or just replace it (if it does read bad)

Offline Trofeo

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Re: Extremely bad fuel economy MK4 GTI
« Reply #6 on: August 25, 2020, 12:37:47 pm »

Should i start with a MAF cleaner or just replace it (if it does read bad)
[/quote] I've never had success with cleaner. You can try unplugging the maf and see if the car performs any different. If no change then you know the maf is dead.
2015 Amarok 4WD auto
2018 Golf R-Line Tsi

Offline superfueler

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Re: Extremely bad fuel economy MK4 GTI
« Reply #7 on: August 25, 2020, 04:34:07 pm »
I have a stock 5 speed tiptronic mk4 GTI which does horrible gas mileage, im not sure when it started since i got the car used and just never really paid attention until i found out that these cars should be able to do 500-650km on a full tank while mine struggles to go 400km. I knew the previous owner didnt maintain the car properly so can someone give me some pointers on what to check/replace/clean/fix to help with this issue. Its a pain in the ass since im a broke uni student and fuel is really eating up my wallet.

I know aggressive driving doesnt help but honestly i drive like a nana most of the time

Oh and another question, is it necessary to run 95/98 on these cars?

Wow, i get way more kms in my R32. Might as well sell and go VR6.  :D
I also think that cheaper fuel like 91 will make a difference in consumption then 95 or 98. Stay away from the green nozzle!  ;)
When last did your GTI have a good service (oil, filters and plugs)??
« Last Edit: August 25, 2020, 04:36:34 pm by superfueler »
Current: 2004 Golf mk4 R32 black, 2010 Audi A4 2.7 TDI silver.
Past: 2009 Audi S3 white, 2004 Audi A4 B6 1.8T blue, 99 Golf mk4 GTI black, 2005 Audi A4 B7 2.0T black.

Offline DaffaN

  • Posts: 15
Re: Extremely bad fuel economy MK4 GTI
« Reply #8 on: August 25, 2020, 10:04:24 pm »
Wow, i get way more kms in my R32. Might as well sell and go VR6.  :D
I also think that cheaper fuel like 91 will make a difference in consumption then 95 or 98. Stay away from the green nozzle!  ;)
When last did your GTI have a good service (oil, filters and plugs)??

Ahahah yeah i was surprised when i found out my car does round about the same as a V12 gtc4 Lusso, and yeah dont worry ive been using 95/98 just making sure im not wasting my money. Service is due soon so ill see if thatíll make a difference

Offline the phantom

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Re: Extremely bad fuel economy MK4 GTI
« Reply #9 on: August 26, 2020, 09:46:50 am »
Mines a turbo, i wouldve sold it already if its the 2.0 ahahahah



doesn't diminish the fact that cleaning the throttle body could make a difference

Land Transport New Zealand, taking the fun out of driving since August 2008

Offline LouieP

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Re: Extremely bad fuel economy MK4 GTI
« Reply #10 on: August 26, 2020, 10:26:32 am »
What sort of distance do you do though? I had a mk4 gti back in 2015, it was a manual though. I used to run mobil 98/BP on mine only. It ran very funny on Z 95. Also who told you they get 650km/ tank. That's a vague assumption

1. Get car scanned
2. Clean MAF, TB
3. Change plugs
4. Change fuel filter
5. Boost leak - all the lines should be shot by now.

Not much more you can do without getting it scanned though. They are slow cars so you find yourself pressing the accelerator a lot more than other cars to get it going
« Last Edit: August 26, 2020, 10:30:29 am by LouieP »
2014 MK7 Golf GTI - Pure White
1996 MK3 Golf VR6 - Black Magic Pearl

Offline DaffaN

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Re: Extremely bad fuel economy MK4 GTI
« Reply #11 on: August 27, 2020, 05:02:57 pm »
What sort of distance do you do though? I had a mk4 gti back in 2015, it was a manual though. I used to run mobil 98/BP on mine only. It ran very funny on Z 95. Also who told you they get 650km/ tank. That's a vague assumption

1. Get car scanned
2. Clean MAF, TB
3. Change plugs
4. Change fuel filter
5. Boost leak - all the lines should be shot by now.

Not much more you can do without getting it scanned though. They are slow cars so you find yourself pressing the accelerator a lot more than other cars to get it going

Ahh yes this is the type of list im looking for, im new to working on my own car so this really helps. As for distances i do, its mainly going to work (avondale-newmarket, all motorway), uni (just from my house to train station or all the way to uni which is again all motorway) and running errands in the weekends (100km almost every weekend, id say 75% motorway and highways). 650km is more pf an estimate, when new i think these cars can do up to 12km/L so 650 makes sense although i do understand thats an ideal situation and also age has gotten to these cars, hence why i wouldve accepted low 500kms maybe high 400s, but at the moment its really struggling to get 400 before the fuel lights go off and maybe 20 more kms after that before i really feel i s hould fuel up. As for accelerator, i use it very generously compared to when i first got the car but yeah they are pretty slow, but hey its dirt cheap and its still a ton of fun to drive

Offline LouieP

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Re: Extremely bad fuel economy MK4 GTI
« Reply #12 on: August 28, 2020, 08:48:20 am »
Ahh yes this is the type of list im looking for, im new to working on my own car so this really helps. As for distances i do, its mainly going to work (avondale-newmarket, all motorway), uni (just from my house to train station or all the way to uni which is again all motorway) and running errands in the weekends (100km almost every weekend, id say 75% motorway and highways). 650km is more pf an estimate, when new i think these cars can do up to 12km/L so 650 makes sense although i do understand thats an ideal situation and also age has gotten to these cars, hence why i wouldve accepted low 500kms maybe high 400s, but at the moment its really struggling to get 400 before the fuel lights go off and maybe 20 more kms after that before i really feel i s hould fuel up. As for accelerator, i use it very generously compared to when i first got the car but yeah they are pretty slow, but hey its dirt cheap and its still a ton of fun to drive
Nice one. They are a great platform to learn the basic mechanical's. Easy as to work on, I had proper fun and absolutely loved mine, I would 100% get it scanned, you may find you have a bad sensor somewhere.

My old thread down below, I never finished it but i hope it is of some use to you

http://www.vask.org.nz/index.php/topic,42023.msg442977.html#msg442977


2014 MK7 Golf GTI - Pure White
1996 MK3 Golf VR6 - Black Magic Pearl

Offline DaffaN

  • Posts: 15
Re: Extremely bad fuel economy MK4 GTI
« Reply #13 on: September 04, 2020, 07:53:57 pm »
Nice one. They are a great platform to learn the basic mechanical's. Easy as to work on, I had proper fun and absolutely loved mine, I would 100% get it scanned, you may find you have a bad sensor somewhere.

My old thread down below, I never finished it but i hope it is of some use to you

http://www.vask.org.nz/index.php/topic,42023.msg442977.html#msg442977


Thanks alot Iíll definitely go check out your thread.

Yeah im learning as i go with this car, i love how its easy but not too easy to work on, really got me hooked on VWs this thing

Offline DaffaN

  • Posts: 15
Re: Extremely bad fuel economy MK4 GTI
« Reply #14 on: September 06, 2020, 07:55:25 pm »
Nice one. They are a great platform to learn the basic mechanical's. Easy as to work on, I had proper fun and absolutely loved mine, I would 100% get it scanned, you may find you have a bad sensor somewhere.

My old thread down below, I never finished it but i hope it is of some use to you

http://www.vask.org.nz/index.php/topic,42023.msg442977.html#msg442977


Did a quick read and loved your thread, exactly what im looking into for my car, just a nice, clean oem plus car - i see to much mk4 gti ruined by teens with raging hormones (**me**) im gonna keep thus sucker for as long as i can

Offline superfueler

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Re: Extremely bad fuel economy MK4 GTI
« Reply #15 on: September 11, 2020, 05:39:52 pm »
Got it fixed yet??  :D
Current: 2004 Golf mk4 R32 black, 2010 Audi A4 2.7 TDI silver.
Past: 2009 Audi S3 white, 2004 Audi A4 B6 1.8T blue, 99 Golf mk4 GTI black, 2005 Audi A4 B7 2.0T black.

Offline DaffaN

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Re: Extremely bad fuel economy MK4 GTI
« Reply #16 on: September 14, 2020, 05:04:54 pm »
Got it fixed yet??  :D

The solenoids in the 09a inevitably failed so i havent done anything to the car since - in fear that itll just be a waste if i get rid of the car.

Worry not though, im doing a cut and polish on my mates car and in return him and his dad will do the solenoid job for free, if thats all done im going back to full restoration mode