New owner. Terrible fuel milage?

[razgriz10000]

Hello all. I'm a new owner of a 2007 A4 2.0t quattro. I did a 250 mile, nonstop highway ride and when I filled up and calculated the milage I only got 20.7 mpg highway. (75mph on cruise the whole time) The past couple of weeks I've only been averaging 16ish mpg city. I've searched some other threads and heard the usual tire pressure, air filter, etc... (which I've checked) but this seems much more drastic. No CEL or anything, and even hooked it to my Bluetooth obd scanner and can't see anything obviously wrong. What are some things could affect milage that drastically?

Appreciate any and all help

-Eric

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[jimrobbington]

Bad gas, old spark plugs, dirty maf

[Gmoney1147]

Weather plays a factor, I know that cause during the cold morning months here in California I went from 400 miles a tank to 340-360


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[mec]

Bad gas, old spark plugs, dirty maf

you can add Busted N205 to that.

[razgriz10000]

Only use premium from reputable stations. No meijer or Kroger or Valero gas for me... Stuff like that. Plugs are only 2k miles on them. Have not checked the maf yet.

It is cold here but my very first tank only took me 270 miles from full to the 40 mile warning light. Seemes a bit low to me even with cold and winter blend fuel.

N205? You'll have to bare with me. I come from the world of big diesel trucks. This is my first car, and first vehicle with less than 8 cylinders and first gasoline engine lol. I know very little about these smaller cars as of yet. Still learning. What's the N205?

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[jimrobbington]

You should at the very least get 26 or 27 mpg mostly highway. I think 32 ish might be my best on a long trip. I just got 19 mpg mostly city on an e85 mix. Had to fill up before 300 miles.

[razgriz10000]

Well that's what I figured. I mean, I don't expect a miracle but I figured 20 on a highway trip? That just seems way off.

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[jimrobbington]

Depending on milage, and driving style of the majority of the car's life, carbon buildup could be a factor.

Do you have rough cold starts or anything weird at low rpm driving?

[razgriz10000]

Fires right up. No shaking. No sputtering. No smoke. It seems perfect. I am 2nd owner. 90k miles. It has had all its scheduled maintenance up til I bought it (verified with papers)

When really cold the RPMs will surge up and down 100rpms at low throttle til warm. I've seen on a bunch of other threads the same symptoms and they all seem to say the same thing. that that is common and caused by a bad torque converter. Other than that it seems fine to me but then again it's my first 2.0t so I might not even feel if something is 'off' about the way it drives.

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[trj]

Welcome to the wonderful world of poor mpg 2.0 t.

I have been trying to figure out the same as well. Plugs, filters, gas, MAF cleaning, all done.
I get about 240 miles on a tank.
Now I am doing diverter valve, n75, n80 soon.

But I suspect my thermostat has gone wonky too. Sometimes when it's cold, highway driving for sometime gets the needle towards left of the 90 degree mark. So will be doing the whole timing belt job along with the thermostat.
Hopefully that will bring the mpg up. Else I will just drive my other car. More cylinders and more power, yet better mpg.

[yeoj112689]

I easily get 350 miles per tank sometimes way more... depends how you drive as well, if you drive like a monster it goes way down (ask me how I know lol).

Look for boost leaks, MAF is a huge thing, and look for small problems that add up to large ones. Probably an easy fix.

[razgriz10000]

Are there any common boost leaks? I've heard of the old style diverter valve tearing. I'm not sure which one I have yet as I've been waiting for it to warm up before climbing underneath and checking. What are some other prone areas to leak boost? I'll check those out too.

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[Audibot]

Welcome to the forum, OP.

If you're changing out plugs, coil packs, and such, be sure to replace the fuel filter too. Possible it hasn't been done. As mentioned, winter gas will reduce fuel economy (no idea why they even use winter gas). In the winter, I can get high 20s mpg on the highway. Summer, I can get up 33. So it varies, but 20 is WAAAAY too low for highway driving.

As a member you should be able to do a search to find the N205. Assuming you'll be doing work yourself, the Bentley manual is super helpful too (though it certainly does not have ALL the answers).

[Audibot]

Are there any common boost leaks? I've heard of the old style diverter valve tearing. I'm not sure which one I have yet as I've been waiting for it to warm up before climbing underneath and checking. What are some other prone areas to leak boost? I'll check those out too.

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If it's never been changed, you probably have the Rev C DV (I too had that in my 2007 until it was swapped out). If it was torn, you'd get a check engine light for boosting.

[razgriz10000]

Well there's no CEL but I still wanna check it when I get the car off the ground some time. And yeah, I'm an Aircraft mechanic so believe me, doing my own car work doesn't scare me lol. I'll change the fuel filter too then just in case.

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[B44]

as mentioned above by our fellow members here is the list

1. check and clean maf
2. check air filter if stock replace if custom can be cleaned
3. replace fuel filter if driven more than 80k
4. spark plugs and coil packs check
5. do not drive in cruise control thats the worst you do to your car. dont let it sit on one rpm drive then let off gas then drive again.

hope this helps.

[kegobeer]

as mentioned above by our fellow members here is the list
5. do not drive in cruise control thats the worst you do to your car. dont let it sit on one rpm drive then let off gas then drive again.

Huh?

The car doesn't care if a computer is controlling the throttle or my foot is controlling it. The only time you shouldn't use CC is in stop and go traffic. CC does absolutely no harm to an engine or transmission.

[DannyDeez]

Depending on milage, and driving style of the majority of the car's life, carbon buildup could be a factor.

Do you have rough cold starts or anything weird at low rpm driving?

I have rough cold starts. And by rough, I mean it cranks for a bit before it starts up. Should I be worried?

[jimrobbington]

I have rough cold starts. And by rough, I mean it cranks for a bit before it starts up. Should I be worried?
Maybe, but not what I meant. I meant running rough until it warms up.

[mtroxel]

a do not drive in cruise control thats the worst you do to your car. dont let it sit on one rpm drive then let off gas then drive again.




Huh?

The car doesn't care if a computer is controlling the throttle or my foot is controlling it. The only time you shouldn't use CC is in stop and go traffic. CC does absolutely no harm to an engine or transmission.

What he means is................................................ .....................ummmm.....I have NO idea how that makes sense.

[aluthman]

as mentioned above by our fellow members here is the list

1. check and clean maf
2. check air filter if stock replace if custom can be cleaned
3. replace fuel filter if driven more than 80k
4. spark plugs and coil packs check
5. do not drive in cruise control thats the worst you do to your car. dont let it sit on one rpm drive then let off gas then drive again.

hope this helps.

#5 says to me you have no idea what you're talking about. By that logic, 100k of highway miles is harder on a car than 100k of city miles, which is simply not the case.

[Audibot]

5. do not drive in cruise control thats the worst you do to your car. dont let it sit on one rpm drive then let off gas then drive again.

I think this only applies when you're breaking in a new car.

[kegobeer]

I think this only applies when you're breaking in a new car.

Nope, not even then. Varying the speed during the first 1000 miles happens any time you drive it. There's no requirement to avoid using CC during that time.

[Mlambrecht17]

I'm having the exact same problems, I just had the car carbon cleaned, new pcv, and I scanned it, there were no codes. Still having the problem, I'm thinking I'm gonna try spark plugs, cleaning the MAF and air filter(I have a cone filter on it rn) and maybe a new fuel filter, I'm at 101k, any other help would be great

[yeoj112689]

I have rough cold starts. And by rough, I mean it cranks for a bit before it starts up. Should I be worried?

I have this as well, scared me for a second lol.

[razgriz10000]

I'm having the exact same problems, I just had the car carbon cleaned, new pcv, and I scanned it, there were no codes. Still having the problem, I'm thinking I'm gonna try spark plugs, cleaning the MAF and air filter(I have a cone filter on it rn) and maybe a new fuel filter, I'm at 101k, any other help would be great
Let me know if anything you do makes a difference for you. I'm just waiting on some warmer weather before I start digging into mine. Just trying to get some ideas.

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[customa4]

OP, you ever looked into BG44K? It's like a miracle in a can. You will achieve great results from it, plenty have used it with a positive outcome. Here's a thread I made in the B6 forum last year to get some opinions. Click (http://www.audizine.com/forum/showthread.php/591487-Who-has-used-BG44K-What-are-your-thoughts-(Or-any-other-BG-products)) You can pick it up at most dealerships since they use it as their fuel system cleaner. I've gotten it from Toyota, Nissan, Audi and VW since I've started using it.

[DannyDeez]

Maybe, but not what I meant. I meant running rough until it warms up.

Oh ok.. thanks [up] Mine runs fine when I start it so I won't worry then.

[razgriz10000]

OP, you ever looked into BG44K? It's like a miracle in a can. You will achieve great results from it, plenty have used it with a positive outcome. Here's a thread I made in the B6 forum last year to get some opinions. Click (http://www.audizine.com/forum/showthread.php/591487-Who-has-used-BG44K-What-are-your-thoughts-(Or-any-other-BG-products)) You can pick it up at most dealerships since they use it as their fuel system cleaner. I've gotten it from Toyota, Nissan, Audi and VW since I've started using it.
How often do you use it now? With almost 100k miles on the clock it can't hurt. I'm sure my valves and injectors will love it.

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[p0isin]

I haven't read all the replies but here is my input. My tstat has been stuck open for the past couple months. This has caused my gas mileage to decrease to ~22mpg highway and ~18 mpg city. Engine is constantly trying to maintain optimal temperature but temp gauge needle moves between 1/4 and 1/2.

I'll be fixing it soon but that could be a reason for your bad mileage too.

[Biged243]

OP, you ever looked into BG44K? It's like a miracle in a can. You will achieve great results from it, plenty have used it with a positive outcome. Here's a thread I made in the B6 forum last year to get some opinions. Click (http://www.audizine.com/forum/showthread.php/591487-Who-has-used-BG44K-What-are-your-thoughts-(Or-any-other-BG-products)) You can pick it up at most dealerships since they use it as their fuel system cleaner. I've gotten it from Toyota, Nissan, Audi and VW since I've started using it.
That won't have the same affect on our cars because of direct injection.

[Dirt Yota]

I too had some poor gas mileage and realized on my morning rides to work the temp needle would drop below half just cruising on the freeway. Replaced the T stat, t belt etc.. and now mileage is back to where it should be. In "Open Loop"(Engine warm up) the engine runs way richer, if the engine never see's full operating temps it can never get into "Closed Loop" which is operating temp and leans the engine out. So a stuck open T stat will cause the engine to never enter "Closed Loop" and therefore continue to run rich and burn excessive fuel.

At 100k the car is due for this major service. Sometimes the T stat will throw a code if it gets really bad.

[Audibot]

That won't have the same affect on our cars because of direct injection.

Partly true. BG44 has an option to hook it into the manifold where the coupler meets the throttle body (from what I've seen). From there, the chemical is run in over the valves to help "wash" away carbon deposits. Nowhere near as effective as scrubbing them down, but it's not a complete waste.

When I had carbon cleaning done, they did the manual cleaning first, then the BG44 treatment to give them a good wash.

[Biged243]

Partly true. BG44 has an option to hook it into the manifold where the coupler meets the throttle body (from what I've seen). From there, the chemical is run in over the valves to help "wash" away carbon deposits. Nowhere near as effective as scrubbing them down, but it's not a complete waste.

When I had carbon cleaning done, they did the manual cleaning first, then the BG44 treatment to give them a good wash.
Your right you can do it that way kinda like the sea foam with the vacuum port on the manifold and run the engine regulating the suction so it doesn't kill the engine. I agree that if it is done this way it isn't a complete waste. However it mostly hits the front of the valves so the rear of the valves still get build up. I was under the assumption that he was talking about just dumping it in the tank and going.

[razgriz10000]

Update

I'm starting to think it may be a boost leak. Not only am I not even going to make 300 miles on one tank
http://tapatalk.imageshack.com/v2/15/03/11/e5ec2f0894444cecc7999a59221c607f.jpg

But with weather warming up and dry roads, I decided to do some 0-60 tests. This was my time with building boost as well
http://tapatalk.imageshack.com/v2/15/03/11/997261548c3c7bb5665f7972195a0590.jpg

9.2sec 0-60? I mean I know the 2.0t isn't a race car but that seems terribly slow. Also, 120 approximated HP max? I know the torque pro app isn't exact but it was always pretty accurate with my diesels so 120 when it should be up around 200 seems to also lead to a possible loss of boost.

Anyone else agree or have other ideas with this bit of new info?
I appreciate all the help thus far.

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[B44]

By cruise control being steady on one rpm not a good idea for the pistons you need to vary the rpm a little if you want longer engine life. Meaning you are driving 80 mph then you want to let of the throttle to let it go by itself to 75 or 70 then accelerating back to 80. I got the piston replaced from audi and the SA said that for a good seal make sure you don't use cruise control and steaddy rpm. Sorry it might be nothing to do with op fuel issue but just information I would like to pass on.

[FraggyA4]

By cruise control being steady on one rpm not a good idea for the pistons you need to vary the rpm a little if you want longer engine life. Meaning you are driving 80 mph then you want to let of the throttle to let it go by itself to 75 or 70 then accelerating back to 80. I got the piston replaced from audi and the SA said that for a good seal make sure you don't use cruise control and steaddy rpm. Sorry it might be nothing to do with op fuel issue but just information I would like to pass on.

I think you misunderstood them, they were meaning that because your rings were brand new you should very rpms in order to get the rings to set. They didn't mean you need to do that all the time just the first couple hundred miles.

Op, check your N205 if you unplug the valve the electrical connection may have oil coming out of it. If it does then it's time to replace and it will have a huge effect on your gas millage.

The N205 is the off color cylinder sticking up on the back of the cylinder head near the fire wall
https://lh4.googleusercontent.com/-gsyCMFzM0Ew/Uy-ZGvdBioI/AAAAAAAAH7I/JW_OV5o5BOw/w737-h553-no/20140323_223143.jpg

[razgriz10000]

Will do. Can the N205 also cause a loss in power as well?

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[FraggyA4]

Will do. Can the N205 also cause a loss in power as well?

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That's probably a boost leak, check all your connection points on the intercoolers. Also check your PCV to see if it's leaking. Unclip the accordian tube from the intake manifold and try and blow through it. If you can it's bad.

[brandonpham]

I think you misunderstood them, they were meaning that because your rings were brand new you should very rpms in order to get the rings to set. They didn't mean you need to do that all the time just the first couple hundred miles.

Op, check your N205 if you unplug the valve the electrical connection may have oil coming out of it. If it does then it's time to replace and it will have a huge effect on your gas millage.

The N205 is the off color cylinder sticking up on the back of the cylinder head near the fire wall
https://lh4.googleusercontent.com/-gsyCMFzM0Ew/Uy-ZGvdBioI/AAAAAAAAH7I/JW_OV5o5BOw/w737-h553-no/20140323_223143.jpg

Someones missing a torx on the coil pack connectors. [wrench]

[razgriz10000]

That's probably a boost leak, check all your connection points on the intercoolers. Also check your PCV to see if it's leaking. Unclip the accordian tube from the intake manifold and try and blow through it. If you can it's bad.
Alright, will do.

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[Mlambrecht17]

How to check for a boost leak?¿ plz help idk what to do

[jimrobbington]

Someones missing a torx on the coil pack connectors. [wrench]
Lol, mine are stripped completely and I don't use those two screws either.