Fuel consumption jumping between 3 and 76 MPG (2004 V8) Huh? - Club Touareg Forums
Reply
 
Thread Tools Display Modes
post #1 of 11 Old 05-02-2017 Thread Starter
Junior Member
 
Touareg: 2004 V8
Join Date: May 2017
Location: Vancouver BC
Second Vehicle: Other
Posts: 41
Thanks: 1
Thanked 5 Times in 4 Posts
Fuel consumption jumping between 3 and 76 MPG (2004 V8) Huh?

Hi all,

Just yesterday I bought a 2004 Treg (V in amazing shape, with just 77,000 miles. I love it, and have plans for a number of tasteful mods/retrofits.

However, my gas mileage has been atrocious - worse than it should be. Today I found that one of my intake manifold link arms is broken, and I'll be ordering a replacement from Gruvenparts tomorrow. Plugs and air filter were just done. The problem is that my MFI is displaying a current consumption that constantly quickly jumps from about 3 MPG to 76 MPG (I wish!) and back down again. It seems to be doing this almost randomly, and does not coincide with my driving/throttle. Anyone heard of this? Is there some sensor that I should be checking? Or could the broken link arm alone account for this?

My Ross-Tech cable is in the mail, so I can't check codes at the moment.

Thanks for any help guys
Whim is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 05-03-2017
Touareg Guru
 
noobytoogy's Avatar
 
Touareg: Still looking
Join Date: May 2009
Location: Brexit Central, England
Second Vehicle: is not a VW
Posts: 20,183
Thanks: 0
Thanked 561 Times in 488 Posts
Can't help on the MPG.

The key item on an early V8 is the timing belt. Change at 80K or 5 years, whichever comes first.

If the belt breaks your engine is toast so unless you know for certain the belt, tensioner, water pump and thermostat have been changed on time, you've already got your first job!
noobytoogy is offline  
post #3 of 11 Old 05-03-2017
Touareg Enthusiast
 
Ionman's Avatar
 
Touareg: 2004 V6
Join Date: Jan 2017
Location: SoCal
Second Vehicle: a bicycle
Posts: 343
Thanks: 2
Thanked 28 Times in 26 Posts
Like Nooby, don't even bother to look at the MFD/MDI for the mileage. If you must, just switch over to the "Since Refuel" MDF display. MFD/MFI, based on my fuel tracking under my Excel file, has anywhere between 1% to 25% error for my 2004. It's unreliable. I do the MPG tallying from refueling. Of course, mine doesn't jump from 3 to 76. Just a suggestion: clean your MAF sensor to start, and I would be looking or wornout/bare spot on the wires within the engine bay. Bad ground tends to create oddball vehicle display. Then just for your own DIY-er mechanic intuition, probe around the car for possible mods that could have cause MFD oddness. VagCom may show you old codes that probably give you a hint on where to go.

As Nooby hits it on the nail, perform a full maintenance. If you are uncertain what the old owner(s) had done, do everything for safe measure.

Once the belt and connected critical components are done, toss in:

Power steering fluid flush
Transmission fluid and filter drain and change (the longest and simple job you can do...emphasizing on the long wait for the drain)
Differential fluid change (pair up with transmission fluid).
Check/replace brake pads and rotors (pair up with transmission & diff fluid job)
While the engine is warmed, do the coolant flush.
Brake fluid flush (do it at the same time with tranny & diff fluid jobs)
Check driveshaft center bearing while you're down below..what the hell..check everything for rots, cracks, rust build-up, and damages. If the old owners were like us, we love to take our vehicle off-roading, exploring the areas were we couldn't with other inferior SUVs.

Sorry to slam it all on you, but high mileage vehicle requires TLC; lots of TLC means long lasting driving pleasure.

- Leo

When life offers you a blessed world to explorer, why stay home and see the adventures through others' eyes.
Ionman is offline  
Sponsored Links
Advertisement
 
post #4 of 11 Old 05-03-2017
Junior Member
 
Join Date: Feb 2017
Posts: 61
Thanks: 1
Thanked 1 Time in 1 Post
The intake runner when it doesn't work it will use up more fuel. Also the arm is broken more than likely the intake manifold is Frozen the runners inside are Frozen. See if you can open and closed Runner manually by hand
raffiseto1 is offline  
post #5 of 11 Old 05-03-2017
Touareg Addict
 
Touareg: 2008 V8
Join Date: Nov 2015
Location: Colorado, United States
Second Vehicle: Other
Posts: 2,065
Thanks: 1
Thanked 136 Times in 132 Posts
Yes. Lots of EXPENSIVE TLC! LOL!!

2008 V8
No VCDS? Get it here:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
FSJ Guy is offline  
post #6 of 11 Old 05-03-2017 Thread Starter
Junior Member
 
Touareg: 2004 V8
Join Date: May 2017
Location: Vancouver BC
Second Vehicle: Other
Posts: 41
Thanks: 1
Thanked 5 Times in 4 Posts
Thanks for the advice guys. Iím happy to say that the truckís been well-maintained (timing belt/water pump done, regular oil/filter, various system flushes, etc.). That said, Iím gonna do all that stuff again. I do NOT want any differential or tranny issues.

My new VCDS cable should be here tomorrow. I have a Micro-CAN because I had a MK5 Jetta, but itís no good with the Treg. Looking forward to delving back into this truckís history.

MAF cleaning will happen tomorrow Ė thanks Ionman. Iíll also take a look at wiring in the engine bay. The sound/heat insulation matting under the hood has some suspicious damage (i.e., chew marks) . So it may be that some rodent made a dinner of some wire sheathing.

raffiseto1 I can turn the flap pivot with the broken arm fairly easily and smoothly. It turns with about as much force as it takes to turn a can opener. Iím hoping that the new arm (and cleaning up the valve) will improve things.

Any of you ever use products any intake manifold cleaning agents? Seafoam? Iíve heard mixed reviews about using that kinda stuff with FSI motors.
Whim is offline  
post #7 of 11 Old 05-03-2017
Touareg Addict
 
Oregon TDI's Avatar
 
Touareg: Still looking
Join Date: Feb 2015
Location: Oregon
Second Vehicle: Other
Posts: 1,953
Thanks: 141
Thanked 203 Times in 160 Posts
Garage
Are you viewing Since Refuel or Long Term / Extended MPG data? Sounds like you're displaying the "instantaneous" data which will jump around wildly.

In spite of everything, I still like Volkswagens.
Oregon TDI is offline  
post #8 of 11 Old 05-03-2017 Thread Starter
Junior Member
 
Touareg: 2004 V8
Join Date: May 2017
Location: Vancouver BC
Second Vehicle: Other
Posts: 41
Thanks: 1
Thanked 5 Times in 4 Posts
Long term consumption is at around 7 MPG but it can go up to like 18 MPG within about a minute. Current consumption is what jumps around the most.

I'm happy to just calculate manually based on miles per tank, and I will. I just don't like having anything that isn't working properly. Seems to me like it would be a sensor issue.

I wouldn't be surprised if the dealership from which I bought the truck put crap gas in it, but I don't think that would confuse the MFI that much
Whim is offline  
post #9 of 11 Old 05-03-2017 Thread Starter
Junior Member
 
Touareg: 2004 V8
Join Date: May 2017
Location: Vancouver BC
Second Vehicle: Other
Posts: 41
Thanks: 1
Thanked 5 Times in 4 Posts
And I do understand that current consumption will hit the ceiling when you hit the gas, but it should never get anywhere near the 70s
Whim is offline  
post #10 of 11 Old 05-03-2017
Touareg Enthusiast
 
Ionman's Avatar
 
Touareg: 2004 V6
Join Date: Jan 2017
Location: SoCal
Second Vehicle: a bicycle
Posts: 343
Thanks: 2
Thanked 28 Times in 26 Posts
Quote:
Originally Posted by Whim View Post
Any of you ever use products any intake manifold cleaning agents? Seafoam? Iíve heard mixed reviews about using that kinda stuff with FSI motors.
Mix bag in this forum. I would use it on cars that practically has no option left before a full overhaul, or just too old with nothing left to try. If an expensive job is going to render your budget into a hair raising scream, why not give it a try.

- Leo

When life offers you a blessed world to explorer, why stay home and see the adventures through others' eyes.
Ionman is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Club Touareg Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome
 

VW Touareg News Delivered to your Email!

Stay up-to-date with Touareg news in your inbox.

unsusbcribe at anytime with one click

Close [X]