From 26 to 18MPG and dropping....Help!

[B6A4Dave]

Here's the run down,

Purchased the car a little over a month ago, its an '03 Audi A4 1.8T Quattro, it has 129,*** on the clock, Last time it was at a dealer was 58,***.

The night I went to go test drive the car, the MIL/CEL Came on and it was scanned, came back P0455....I had it in a We Owe from the dealer that they were to fix the problem...however I didnt realize later down the road that no one ever signed the we owe, so after I paid them their money and signed the car over and all that and came back to their maintenance center, they told me...sorry no one signed it...go see the sales guys.

I go see the sales guy and he remember me and was very nice at first....he had his guys try and smoke the car to find the problem, and they yielded no results, they told me at that point that they were done working on the car, too bad for me...Understand they have had the car for about 4 hours total at this point. Note that the have had it in their possession for about 8 hrs, 4 of which I waited and they didnt even pull the car into the shop and I said fuck you im leaving.

So, I work my way over to my Local Audi guys and talk to them, expediently and promptly they get the vehicle in, asked if I needed a curtesy transport anywhere, home, work, etc. I told them I'd wait for the car it was no big deal, they were quick to offer coffee and such.. Regardless, several hours later they were able to deduce the problem was a Large evap leak at the line from my Fuel tank to my Filler neck, they got the part from the parts department, showed me where they found it was broken and offered 2 solutions
1) about $250 and they could try and Repair the damaged line.
2) Replace the line...however due to its location its 10.5hrs of labor and about $1300 to fix...$1245 if I recall.

Option 2 involves removing the rear subframe, rear differential, rear suspension, drive shaft, fuel tank and all back in again to replace....thus the $$$$ and labor hours

However, I now know what is continually setting my MIL/CEL for P0455...While Im not saying that ISNT my culprit of my poor MPG, I dont think its the main cause.. the problem has been there since I purchased the vehicle, why the sudden deterioration? and even if, its very cold here in Colorado and the fuel is less prone to changing into vapor due to the temperature changing the density..

So, on the other note, here is a list of all the work currently done since I got it..
Timing Belt
Timing belt tensioner
Timing belt idler pulley
Water Pump
Oil Change (0w40 Mobil 1)
Mobil 1 Oil Filter
AFE Air Filter
Plugs replaced and Gapped to spec.
Coil packs replaced (Warranty Replacements)
Only ran Shell Premium fuel through it ( 1st two tanks contained a fuel treatment (it was free...I dont actually think this shit works))

So....
When I did the plugs I did notice some oil build up on the back of the ceramic insulation. So I am going to get a new Valve Cover Gasket set from Audi, as well as get a Fuel filter and OE oil filter.

Unknown when the fuel filter was last done,...so I'm hoping to see positive things come from that..

Other actions to be taken, Seafoam based on http://www.audizine.com/forum/showth...ow-To-Sea-Foam
and then the Oil change..

So, next to come is..
OE Valve Cover Gasket kit (might order from ECS if cheaper than dealer)
OE Fuel Filter
Oil Change with Mobil 1 0W40 and OE Oil Filter
Seafoam
Check plug condition

Regardless, recently in the past 5 days I've lost 8MPG....if I dont find what is causing my ridiculously poor mileage soon Im going to say fuck this car and sell it, It's no longer worth the fuel it takes to operate..

My 410whp Civic got 20MPG on an Alternative fuel (E85)...this 18mpg is bullshit. 26 was poor enough, but this is a fucking joke.

Anyone.....give me something, and dont tell me to try and fuck over the dealer who sold me this car...Ive tried...its a frivolous effort. I got fucked....

- Dave

Calling OLD GUY!!!! For the love of god help! hah

[A4natomical]

So I am going to get a new Valve Cover Gasket set from Audi, as well as get a Fuel filter and OE oil filter.

valve cover gasket and oil filter will do nothing to your mileage. If you're going to drop money, I'd drop it on 02 sensors, maf, map, air filter along with what you already bought (plugs and fuel filter).



I'd recommend chilling out, crackin a bunch of beers and watching the game....

[old guy]

I agree with A4natomical. If you have an original original O2 sensor it should be replaced. Cleaning the MAF sensor couldn't hurt either. If the leak causing the P0455 is bad enough it can definitely mess with your mileage. Normally the N80 sucks any excess vapors through the evap control system (charcoal canister) in a controlled manner. With a large leak you will be drawing excessive air through the N80. This enters the intake manifold without being metered by the MAF. The result is the O2 sensor reads the lean condition and reacts by adding additional fuel. You can check your fuel trims (block 32) to see if the ECM is adding fuel.

[B6A4Dave]

valve cover gasket and oil filter will do nothing to your mileage. If you're going to drop money, I'd drop it on 02 sensors, maf, map, air filter along with what you already bought (plugs and fuel filter).



I'd recommend chilling out, crackin a bunch of beers and watching the game....

My only thought with the Valve cover gasket is that it may be leaking oil onto my plugs and fouling them out, or damaging my coil packs.

I still want to do it because I dont like any oil consumption, is it worth going OE on the valve cover gasket? or any local parts store should be okay?

I'll look into the O2 sensors, wouldn't the PCM pick up something on that? Voltage below specified threshhold? something...these damn cars cant have 0.00001v wrong in a circuit without throwing at least a pending code it seams >_<. Regardless, I'll look at the sensor voltages on the O2 sensor, I fear that O2 sensors for this car are going to be stupid expensive...Bosch LSU 4.2 Wideband sensors I think...same one I used in my Civic for WBO2 to tune AFR.

MAF Will definitely atleast get a cleaning and have the sensor voltage checked to specifications on ShopKey (formerly mitchell online)

Not sure what to do with MAP?

Air filter has been changed for an AFE dry synthetic. and I'll check plugs again and do the fuel filter.

I agree with A4natomical. If you have an original original O2 sensor it should be replaced. Cleaning the MAF sensor couldn't hurt either. If the leak causing the P0455 is bad enough it can definitely mess with your mileage. Normally the N80 sucks any excess vapors through the evap control system (charcoal canister) in a controlled manner. With a large leak you will be drawing excessive air through the N80. This enters the intake manifold without being metered by the MAF. The result is the O2 sensor reads the lean condition and reacts by adding additional fuel. You can check your fuel trims (block 32) to see if the ECM is adding fuel.

MAF for sure will get cleaned.

Im still wondering if that is all my problem is....is that EVAP leak..

N80 valve, can I get a diagram or a location for that? I think I know...thats the one attached to the OE air box correct? Is there a way to check that its working? I believe when the dealer checked my car they said my EVAP Purge valve was good, which I believe is the N80...correct?

I'm going to see if I can hook the car up to my friends ETHOS tonight and watch the sensor data...I know its not a VAGCOM, but its better than a walmart scanner lol


tryin to relax...but the baby mom is up my ass about the car

[old guy]

Yes the N80 is the evap purge valve. It is located above the air box. Once the car is running you should be able to hear the N80 clicking as it runs a continuous duty cycle most of the time.

[B6A4Dave]

I'll be sure to check that out...

What do you guys normally get for MPG?

I was talkin to a guy last night with a B7 A3 on an APR 2+ flash saying he gets almost 30 highway and 28 city if he stays outta it...now I get that B7 is FSI and better for MPG but still....

[olstyn]

26 is on the low side of normal for highway mileage. When my commute was 27 miles highway one way, I'd usually average 26-28 MPG (calculated from gas pump + odometer numbers - the car's computer thought it was getting more like 28-29). 18, on the other hand, sounds like city driving with a lot of uncooperative stoplights. My car is an unmodded 1.8T. Now, with a shorter commute, I see more like 24 MPG average, which makes me sad, but is understandable, as I spend a lower percentage of my driving time in highway cruising. For the record, EPA rating for these cars is 21 city, 29 highway, just to give another point of comparison.

The A3 is a smaller car, and lighter = better mileage, but I have a hard time believing the 28 city.

[B6A4Dave]

I've always found EPA ratings to be too low to be honest...

I dont think its city driving that is doing it, cause I spend a decent amount of time on the highways, and the speed limit in Colorado 75mpg, I dont go above 65 most of the time...and yes, I stay in the right lane :P

I've tried it with using my foot, and with cruise control to see if it makes a difference...

But this decreased mileage is someone all of a sudden and a drastic drop...Unless my EVAP line just completely split open....which is possible.

Im driving in cold air conditions too, hoping the density will help me somewhat...but idk, have a lot of researching and digging around to do

[Valve_Cover]

Hmmm, stage 2 Uni, TT injectors, no cat, full exhaust and I get 7,9l / 100 km highway. Thats like 29.7mpg and I drive 120km/h (75mph). And thats my average during these cold winter days, which is atleat 5-8% better in summer, where I've seen as much as 34-35mpg when really going grandpa style. My city driving is freaking abysmal though, like 15l / 100km, (roughly 15-16 mpg) mainly because my commute is so short my car doesnt have time to warm up, plus it idles more in the morning before I leave. In summer I'll get 9l / 100km city, which equates to roughly 26mpg, but thats when staying off boost whenever possible.

[maurizio]

In the summer i maintain 28mpg's mostly highway. Now, however.... (im blaming this winter blend crap, still get 25's or so)
Im done worrying about it

[B6A4Dave]

I'd love to be able to maintain 26mpg even....sounds like you guys are doing much better than I am.

@ Valve cover - Seems as though you're outside the US given by your measurements, are yo privileged with the Euro Jungle Juice fuel?

Premium in the UK = 103 oct.

[87supraman]

I noticed a similar drop with my 3.0 recently, and put the battery on the charger over night and now I'm back to normal... Probably not your issue, but it might be worth checking your battery voltage.

[A4natomical]

My only thought with the Valve cover gasket is that it may be leaking oil onto my plugs and fouling them out, or damaging my coil packs.

I still want to do it because I dont like any oil consumption, is it worth going OE on the valve cover gasket? or any local parts store should be okay?

Oil leaking from the valve cover should in no way foul your plugs out. The only way oil would affect voltage would be if the oil filled the sparkplug chamber enough to interfere with the coilpack-sparkplug connection, which is highly unlikely. I'd still change the gasket anyway if it's leaking.

Just order the gasket from purems.com or some other equivalent.



My mileage has dropped quite a bit since I put my OE catalytic converter back in from the previous installment of a test pipe. That probably has nothing to do with your issues though. With the OE cat I get a combined 22mpg on average with my mods. With my usual fill up of about 15.5-16 gallons, I yield about 345-350 miles compared to my previous 400 miles per tank with a test pipe.

[B6A4Dave]

Alright so...tonight's findings were rather good!

Hooked up the scan tool to the car and my O2 sensors appear to be just fine...amen on not having to replace those.

I believe I found the source of my giant EVAP Leak, there was liquid fuel on the line that had the hole in it, and the liquid was right near the hole...definitely gas. I believe I have a way to repair it...ha.

Found that my plugs are all white...3 out of 4 at least, those same 3 had oil on the plugs from where I knew my valve cover gasket was leaking, other old oil leaks are also visible around the valve cover...so that is to get replaced..

Im going to wait on replacing the plugs, cause I think the oil is adding resistance and thus not getting enough voltage and spark to those cylinders..No sign of destructive detonation, however there were some spots on the plugs that are of some concern..however I'll see if the valve cover gaskets will help that..May check the resistance of the plugs in the motor to see if I have high resistance on 3 of those cylinders.

the plug with the least oil appeared to be the goldest plug so appears to be the happiest cylinder, May need to run a leakage test to see if there is another culprit for my white plugs besides the oil..

However, Seafoam, Oil Change, fuel filter, valve cover gasket, and DIY Repair on the EVAP line tomorrow with some friends.

Sucked all the shit out of air box with a shop vac too...so, all good thus far.

Scan tool showed long term fuel trim at +7% so I think its maxed out...potentially Evap leak and other things causing that, another possibility for the white plugs...but why not all 4.

hopefully tomorrows work will yield results..

one loss though, my right rear bulb went out..thank you fancy smart computer for telling me..so replacing that too...hopefully Ill be on my way to 28+mpg after all this

here's the break in the line..

somewhat difficult to see..but follow the tubing and there is a small tear.

[Valve_Cover]

I'd love to be able to maintain 26mpg even....sounds like you guys are doing much better than I am.

@ Valve cover - Seems as though you're outside the US given by your measurements, are yo privileged with the Euro Jungle Juice fuel?

Premium in the UK = 103 oct.

I'm in Canada, thus the 'rest of the world' measurments haha! :P And yea we have better gas up here, mainly MMT based gas, and 94 octane. Its expensive though (1.50$ a liter) , but its some damn good gas.

And as for your 7% fuel trim, you arent maxed. Long term and short term can go up to 20% for a total of 40%. But if a combination of both yields more than 20% total,you'll get a P0171 fuel system too lean.

[samer1abbas]

I've got a bone stock 1.8T and I'm only getting 24.6mpg according to the car on 90% highway driving between 70-85mph. I definitely expected better from such a small engine but I also noticed that in 5th gear highway driving I'm near 4k rpms (I shift before 3k most of the time to try and drive economically). My old buick barely hit 2k rpms when going 80mph and averaged better on the highway with a 3.8L supercharged engine than this little 1.8T...

[The1nutwonder]

ive got a 3.0 and i get about 26mpg on my commute which is 12 miles one way no highway. and when the wif was driving it to her work its 30miles one way mostly 65 mpr and she was up around 30 mpg. and i tested 2 tanks each just to be sure.

[olstyn]

Wow, 1nut, that is insanely good fuel economy for the 3.0 V6; in fact, it's the best I've ever heard of with that engine.

[fr0sty]

I dont like any oil consumption

You might own the wrong car then. Oil consumption is quite common with the 1.8t.

[The1nutwonder]

all i did was the zingo mod and keep my foot out of it. and im suprised my wife can do it. i regularly see the mpg gauge read 32-34 but tested at the pump i dont get that. i cant wait to see wat the jhm tune would do because i hear that frees up some mpgs aswell.

oh and i do keep the car fairly empty only thing that didnt come with the car that stays in there is a small tool set and a kids seat. and i religiously check tire pressure literaly every other day if not everyday.

[gibberer]

I have to ask, what is the Zingo mod?

[The1nutwonder]

I have to ask, what is the Zingo mod?

http://www.audizine.com/forum/showth...d=12&styleid=8

its an airbox mod that basicly turns ur stock intake into a cold air intake. u get a slight hissing noise but its not terribly noticable and it def helps out with the mpgs.

[ECS Tuning-Audi]

You wouldn't believe how much your gas mileage would improve if you drive the speed limit. Majority of us speed at least a little ( I usually tend to not do more than 10 over) but even slowing down to just 5 over or doing the exact speed limit you will improve your fuel economy.

Coolant temp sensors and thermostats also play a role in fuel economy. If you have a low reading coolant temp chances are the sensor or thermostat is bad. If the vehicle doesn't reach operating temp the car will be running in "cold start" mode. When the car is running like this it significantly increases the fuel mixture to allow the car to start easier. Obviously if the car does not warm up it will not adjust the fuel trim and you'll be burning more fuel then necessary.

Just my .02

Jason

[Charles.waite]

The thermostat and the grey CTS on my b7 are both inoperative (VCDS reports blank values for each during logging) and my MPG in it is much worse than in my b6. Plus the tailpipes are "smoked" from it running rich due to it dropping into "safe mode" since the thermostat isn't able to be controlled and its receiving no value from the CTS. Either way it has significantly affected my gas mileage and the heater isn't quite as hot as it should be. Its also warming up very slowly due to the Thermostat being stuck open and always cycling Coolant through the radiator. Occasionally during highway driving the engine temp drops below 90C also which is no bueno!

I would follow Jason's advice above and try to find out if either of the CTSs or the thermostat are faulty. If you have VCDS check out measuring blocks 130, 131, and 132. One of those has the Thermostat Duty Cycle, and the temp sensor readouts.

[DPDISXR4Ti]

Oil consumption is quite common with the 1.8t.

I burn none. After ~5000 miles when I go to change the oil, the level is right at the same level as when I filled it ...just not as clean. :)

[Charles.waite]

I burn none. After ~5000 miles when I go to change the oil, the level is right at the same level as when I filled it ...just not as clean. :)

Same here. I'm at nearly the same level as when I filled it in July, ~5k miles ago.

Lots of engines have issues burning oil. Infiniti's VQ series of engines, for instance, has PLENTY of issues with oil consumption and they're Japanese engines. The VQ series in particular are widely regarded as some of the best V-6 engines ever made. Our Audis are neither alone nor special in their oil consumption...

[olstyn]

Haha, you want to complain about oil consumption, go buy an old Porsche with a flat 6 engine...it's considered normal for them to use up 1 quart of oil per 1000 miles. (At least a small amount of oil tends to pool in the horizontal cylinders while the car is off, and gets burned when the car starts up.) For that matter, IIRC Mazda rotaries can use even more than that without being considered to have a problem. The amounts used by 1.8T engines are nothing by comparison. Mine doesn't seem to use any, or at least, it didn't the last time I paid attention to it. It's been so rock steady in that regard that I haven't bothered to check lately. Yes, I know I probably should look at it on a regular basis anyway...

[B6A4Dave]

Well, got the oil changed for some Mobil 1 High Mileage 10W40 Full Synthetic and Mobil 1 Filter.

Got the gaskets changed, seafoamed it, but didnt get to the fuel filter...Audi was all out..

However, for 131k, still looks minty inside.



My parts guy over at Audi said he'll have some in tomorrow...the EGR 90* bend hose broke...it was completely dry rotted and cooked out...so it was replaced with some 5/8ths hose until I can get a new one..

I also think I was able to fix my EVAP leak...for now..

Probably going to pull the battery while I do my fuel filter to let the computer forget then in a week check the fuel trims.

More to come tomorrow..

[Valve_Cover]

Same here. I'm at nearly the same level as when I filled it in July, ~5k miles ago.

Lots of engines have issues burning oil. Infiniti's VQ series of engines, for instance, has PLENTY of issues with oil consumption and they're Japanese engines. The VQ series in particular are widely regarded as some of the best V-6 engines ever made. Our Audis are neither alone nor special in their oil consumption...

I thought the VQ engines were made by Renault, for Nissan? That would make them French, not Japanese

[waldo1324]

I burn none. After ~5000 miles when I go to change the oil, the level is right at the same level as when I filled it ...just not as clean. :)

same-- especially now since i changed VC gasket

[gibberer]

The1nutwonder, Thanks for that - I am looking at buying my first Audi and I am backwards and forwards between the 1.8T and 3.0 - MPG is a big determining factor in the purchase.