What a difference a fuel filter makes!

[eagle]

I have just returned from my trip to the Green Bay, WI area and have posted details (in the January fuel economy competition) through earlier today, but not including a fillup since I got back.

What a difference a fuel filter makes! My TDI is FINALLY producing amazing fuel economy!

I filled up twice on the return trip. Here are the details:

First fillup details:
- tires @ 34 or 35 psi, I forget
- mostly driving around Green Bay, WI and Fox cities (a lot of US 41 travel, with a bunch of city travel in there too, and lots of starts & stops and shortish trips)
- 41.2 mpg at an average speed of 46 mph
- this was on ULSD
- lifetime mpg remains 38.4 mpg

Second fillup details:
- tires @ 36 psi
- 100% highway driving, from Green Bay, WI to Dayton, OH
- 46.4 mpg at an average speed of 67 mph
- this was on D2
- lifetime mpg jumps to 38.6 mpg
- we are driving the car at a rate of 25,500 miles/year

That 46.4 would've been higher (up to 50 mpg - AMAZING!) had I filled up no later than Gary, Indiana. My car's ever-optimistic MFA (it always registers 12-14% high) was showing 56 mpg, which translates to real-world 49.1~50.0 mpg. I'm guessing that was the result of the wind-tunnel effect created by several lanes' worth of dense high-speed traffic, in conjunction with the sound-barricade walls on the side of the highway. By the time I filled up, the MFA was registering "only" 52.5 mpg, which translated to 46.4 real-world mpg.

I will have details of the rest of the return trip (Dayton to Raleigh) once I fill it up, sometime tomorrow.

I am blown away at this fuel economy! I am very excited about my TDI now. I still want a chip upgrade, and paddles for the DSG, but I am extremely happy with my TDI now.

ROCK ON!

[oguzooz]

from 41 to 46 WOWserzr

[eagle]

Originally Posted by oguzooz

from 41 to 46 WOWserzr

HA - that's nothing.

Pre-filter change I rarely saw anything above 40 mpg.

Post-filter change, 39.5 was my lowest, with all but one other fillup being 43.8 or higher. Now, to be fair, almost all of my travel since changing the filter has been highway travel, but the 39.5 was local city travel, and the 41.2 was a lot of shortish trips.

All fillups since the filter change have been: 39.5, 43.8, 46.3, 43.9, 41.2, 46.4.

This is awesome, but I'm really interested to see how the TDI does in local Raleigh traffic now.

[AndyBees]

Eagle, I hate to rain on your "good" fuel economy and obviously yours is improving. However, my "life time" average is over 50 mpg. If my Jetta drops below 50 mpg, I have either been lead footing, stuck in traffic for a considerable amout of time or something wrong with the engine (extremely rare).

I change my fuel filter in December each year regardless of miles (typically between 30k and 35k miles).

On the trip you averaged 67 mph, under similar conditions, my car would have got 55 mpg plus.

[eagle]

Originally Posted by AndyBees

Eagle, I hate to rain on your "good" fuel economy and obviously yours is improving. However, my "life time" average is over 50 mpg.

No problem, but it looks like you have an Jetta IV, not a Jetta V. Jetta IVs are known to get much better economy than the latest generation.

My TDI has been generating sub-40 mpg economy since I got it, with only 2 or 3 exceptions. Since changing the fuel filter, my TDI has been generating economy much more in line with what I was expecting to get from it.

I don't expect to get 50+ mpg out of my car. I'd love to, but I don't think I'll ever see that.

I change my fuel filter in December each year regardless of miles (typically between 30k and 35k miles).

Someone (possibly you) asked me if I carried a spare filter with me, and had the tools to change the filter. I don't... how hard is it to do that? Are there any howtos online?

Update: All I had to do was google for a howto... I found this: http://pics.tdiclub.com/video/cincitdi/index.html

On the trip you averaged 67 mph, under similar conditions, my car would have got 55 mpg plus.

Yeah, I have a friend with a 2004 TDI Jetta, and another one with a 2005 TDI Golf, and they always get high 40s to mid 50s. I doubt I'll ever see that in my Jetta V tho, but mid 40s is awesome to me. (It's rated for 35/42.)

[oguzooz]

Originally Posted by AndyBees

Eagle, I hate to rain on your "good" fuel economy and obviously yours is improving. However, my "life time" average is over 50 mpg. If my Jetta drops below 50 mpg, I have either been lead footing, stuck in traffic for a considerable amout of time or something wrong with the engine (extremely rare).
I change my fuel filter in December each year regardless of miles (typically between 30k and 35k miles).
On the trip you averaged 67 mph, under similar conditions, my car would have got 55 mpg plus.

if you want to get on the bragging issue i guess i will just squash you too. dont bust one someone elses thread like that. he drives a PD. you dont. yours is more broken in then his ( i would assume)

now for the squashing. i get 60mpg+ constantly. my highest tank was 70mpg and some change. hows that feel?

[jnyost]

Originally Posted by oguzooz

if you want to get on the bragging issue i guess i will just squash you too. dont bust one someone elses thread like that. he drives a PD. you dont. yours is more broken in then his ( i would assume)

now for the squashing. i get 60mpg+ constantly. my highest tank was 70mpg and some change. hows that feel?

Nice!!!

I don't like meanyheads either...

[AndyBees]

Originally Posted by oguzooz

if you want to get on the bragging issue i guess i will just squash you too. dont bust one someone elses thread like that. he drives a PD. you dont. yours is more broken in then his ( i would assume)
now for the squashing. i get 60mpg+ constantly. my highest tank was 70mpg and some change. hows that feel?

Well, Oquzooz, I wasn't exactly intending to brag (or squash), just stating a few facts and putting doubt in whether changing the fuel filter improves fuel economy! I have almost 150k miles of detail records in my Excel Spreadsheet. I have never seen a spike or change in fuel economy after changing the fuel filter.

My driving habbits are not exactly tailored to maximize fuel economy either. But, on the other hand, I try to avoid those things that decrease fuel economy; such as using drive-thrus (they are for those.......well, you can fill in the words), jack rabbit starts, no driving in a lower gear when the next higher one will do (4th vs 5th just above lugging RPMs), adhereing to the posted speed limit, no warm-ups, etc.

I feel certain if I was driving a PD instead of my older TDI, it would get better fuel econmy than the average PD just due to my commuter conditions (considerable amount of freeway).

My car is 100% stock with 34 PSI in the tires.

[Gothmolly]

Originally Posted by AndyBees

...
On the trip you averaged 67 mph, under similar conditions, my car would have got 55 mpg plus.

So you're just cooler than the rest of us? Give the guy a break, he was posting some interesting info about the effects of a bad fuel filter on economy. Geesh... compete much?

[MrPolak]

WOW! I bet my Beetle has the original fuel filter in it with 140K miles on the clock. I have a new one sitting in the basement.

I guess I'll change it this weekend, eh?

[jnyost]

I sure would. Up north here we have the ability for ours to gel if not changed often. You could be growing algae in yours...

You may not notice a gain if you change yours often but for those who don't why couldn't they?

[bikeprof]

Mr Polak: Don't you aggre that the air in the basement should be clean enough with the filter there?
I hope it is in a SEALED box and with the inlet tube caps still intact!
Basements collect A LOT of dust!
I have got one, I know..,I'm the one who cleans



EAGLE: Your vehicle is a DSG, these are a LOT heavier and because of other points...DO NOT MAKE the MPG that a Mexican made VW TDI makes.
Yours, has great MPG! with all the comforts of home in your car...and all !
So if you get narrower tires, a CHIP and lower it a "bit"(with them dice)...
You should be able to see 43+MPG for lifetime EASY!

[watercop]

havenevereverchangedmyfuelfilterin4+yearsand168tho usandmiles

There.

I said it.

Now what's this again about fuel filters and mpg? I'd like to hear ideas + theories regarding why or why not a fuel filter change would effect mpg.

I've had a slow fall off in MPG which I attribute to no longer having 4 Energy tires (swapped 2 with X radials awhile back), different trip characteristics, etc.

I no longer place in the top 1-2 in monthly fuel economy contests, but still easily in the top 10.

On my other TDI (The Ford 'stroke) I changed the fuel filter once at 85k or so - it was only slightly dirty. The truck now has 177k and hasn't had another fuel filter since 85k

[mrGutWrench]

Originally Posted by watercop

(snip) Now what's this again about fuel filters and mpg? I'd like to hear ideas + theories regarding why or why not a fuel filter change would effect mpg. (snip)

__. I gather that the theory here is that it's not "normal" filter operation here but some unusual clogging action that's caused some effect that the others of us have never seen. I must say that this whole thing has blown a 1.5 on my BS-alyzer (0.8 is the legal maximum) from the start but -- hey, it's only the Internet and I don't presume to try to measure the effect of fuel starvation through electrons. Who knows ....

[jnyost]

The guy stated how it helped him so why not just get off it.

I can't believe anyone would go that long without changing their fuel filter. I change my PowerStroke filter every 10k. What too many horrow stories about people being stranded on the road.