Audiworld, Audizine, Audi-Forums, VWVortex, Google, Independent shops, and Lazy/Ignorant service managers cannot give me an answer to this problem. It's been a year and to be honest, I'm sick and fucking tired of not knowing WHAT THE FUCK IS WRONG WITH MY CAR. I challenge you, TWW Garage braintrust to ridicule, troll, attack, spit, murder and/or question my sexuality using broken English and various combination of capitalization and grammatical mistakes, just PLEASE FOR THE LOVE OF GOD offer some veiled insight.

Quote :

"I've touched on this in a couple other general 'help wanted' threads of mine but have been unable to come up with a solution. on a 200 mile trip while I didn't think to hook up the vag-com cable I did collect as much data as possible. Maybe the a6 section braintrust can come up with some ideas. I will try to be as clear as possible. ------------------------ 18.5 gal tank filled shows 135 Miles to empty like clock work. (This is my main gripe and I have measured and logged blocks to support why it says 5.0MPG after 15 seconds of resetting) With 20 miles to empty showing on the display I filled up 14.961 gallons which means there had to be 3.539gal in the tank already. After driving 195.1 miles I had 60 Miles to Empty. So if... 20MTE = 3.539gal 60MTE = 10.617gal My 195.1mile trip took 7.883gal. = 24.7 miles/gallon Or with grade school math..... 135......20 ---- = ---- 18.5......x 20MTE = 2.74gal 60MTE = 8.22gal 195.1mi took 10.28gal = 18.97 miles/gal I know that I should have just filled up again as soon as I returned and I would know exactly how many MPG I got, but I'd really like to figure out why my instrument cluster is like this. Any suggestions are much appreciated. I have searched and realize there is a recall dealing with the fuel sending units, but it's my understanding that problem is essentially the opposite of what I am experiencing. Thanks "

Quote :

"I've gone at least 30 miles after the computer reads zero and the warning light is on. I always forget about filling a travel container up. I will definitely do this, but once I do figure out my real MPG (I'm betting it's around 20 for that trip mixed with my city driving from now on) I still won't know why the computer reports only 135 max. --edit "I once went close to 80 miles with a travel container after the 0-10 MTE warning light came on and then realized I had flip flops on so I filled up with ~17 gallons." http://www.elusivity.com/LOG-17-002-010-001.CSV This is my instrument log from a while back. You can def. notice some fishy values under fuel sensor resistance. "

Quote :

"Thanks for the response Daft. The codes I was throwing back in November are listed below. I'm not 100% sure that I didn't accidentally clear them the other night, but I've scanned twice since and they haven't returned. One of the main issues I still have is on a full 18.5gal tank I see... 135 Miles until Empty 5.0MPG avg 20 MPH avg When hooked up to measure the block that gives speed, it was spot on in km/hr. Address 01: Engine Controller: 4B0 907 551 Q Component: 2.7l V6/5VT 0003 Coding: 06752 5 Faults Found: 17544 - Fuel Trim: Bank 1 (Add): System too Lean P1136 - 35-00 - - 16805 - Warm Up Catalyst: Bank 1: Efficiency Below Threshold P0421 - 35-10 - - - Intermittent 17546 - Shareware Version. To Decode all DTCs P1138 - 35-00 - Please Register/Activate Readiness: 0000 0000 --- On the way home today I logged different blocks and then took the car around the block logging a few instrument cluster blocks. The speed seems like it might be accurate. Whenever I hold the reset button while on the MPH display it will read correctly for a short time before falling to 20MPH. I can also reset the MPG and it will read 15-15.2 before falling to 5.0MPG and staying. "

[Edited on October 1, 2008 at 10:55 PM. Reason : 2001 2.7T A6 w/103k]

10/1/2008 10:54:02 PM

Faulty sending unit?

10/1/2008 11:05:55 PM

WTF are all those words up there saying? Something about some gas and miles to empty and then I zoned out.

10/1/2008 11:07:46 PM

^My onboard computer which shows me fuel efficiency and mph/mpg is horribly wrong.

^^maybe, but the fuel sending unit problem with this model was consistent with gross overestimation. IE stranded with the needle on half tank.

How do recalls work exactly? If your VIN hasn't been taken care of regardless of the car's age can you just call the dealership and tell them to fix all of the current TSB problems free of charge?

The Greenville Audi dealership sells primarily Hyundai cars and is shady as fuck though (I think they shorted out my CEL instead of repairing the cause), so I'd have to drive to Raleigh. beethead did you get into APR stuff since we last spoke? Would you know anyone up for a challenge without wanting to charge $Earth in diagnostics?

[Edited on October 1, 2008 at 11:18 PM. Reason : .]

10/1/2008 11:17:08 PM

Quote :

"How do recalls work exactly? If your VIN hasn't been taken care of regardless of the car's age can you just call the dealership and tell them to fix all of the current TSB problems free of charge? "

Call and find out.

10/1/2008 11:40:43 PM

im not touching this.

10/2/2008 12:12:52 AM

Quote :

"beethead did you get into APR stuff since we last spoke"

no. we are not planning on getting apr.

10/2/2008 1:19:42 AM

i saw you mention selling it elsewhere. $$?

10/2/2008 1:42:13 AM

if you care so much you would use grade school math every time. obviously you don't really care. do you expect that thing to compensate for everything and be dead on?

10/2/2008 8:20:36 AM

RAWR RAWR RAWR KNGDOUCHEBAG POST

but really, a lot of words, but it shouldnt be that bad

10/2/2008 8:54:30 AM

No on board computer is very accurate but to get to the point, is this affecting the driveability of the car? If no, stfu.

10/2/2008 1:06:29 PM

Quote :

"On the way home today I logged different blocks and then took the car around the block logging a few instrument cluster blocks. The speed seems like it might be accurate. Whenever I hold the reset button while on the MPH display it will read correctly for a short time before falling to 20MPH. I can also reset the MPG and it will read 15-15.2 before falling to 5.0MPG and staying."

the speedometer not working...that is an issue

10/2/2008 1:08:32 PM

Quote :

"i saw you mention selling it elsewhere. $$?"

me?

we offer software, but not from APR.. we sell unitronic.

10/2/2008 2:32:25 PM

I don't even understand what you are complaining about. Are you saying that your OEM gas mileage gauge is inaccurate? I'm not sure how VW does it, but generally speaking those gas mileage gauges estimate fuel consumption based on throttle position and absolute load. They don't actually measure how much gas been consumed, and don't use the fuel gauge sending unit as an input in the calculation. And you say you are throwing a fuel trim code? If a faulty O2 sensor is giving false lean readings, it's either going to throw in too much fuel (which would affect trims and throw the code) or go into open loop which would generally hurt gas mileage as well.

but since your post made very little sense, what I'm saying may also make very little sense b/c I don't know wtf you are really getting at...

10/2/2008 3:17:08 PM

lean code would typically be maf, vac leak, or o2 sensor

i'm doubting it is an o2 sensor because you are getting a lean code on both banks. i read through some old PMs and you said you were doing logs of the maf reading at some point.. they look about right, but did these codes pop up recently or have they been stored for awhile?

10/2/2008 3:49:52 PM

I know my original post came off as an ill informed bitchfest, but my main concern is that the car might not be running efficiently. To everyone with the mentality that computers are always inaccurate and I shouldn't rely on them anyway, let it be known that something has to be causing these miscalculations. Hell, my check engine light doesn't even light up. I've never actually driven a tuned 2.7T so I have nothing to compare the performance to. Before flashing the engine I need to know it won't be an early death sentence for my turbos creating an endless money pit of repairs. I found some emails with the Audi service manager last year when I was having it repaired before signing the cashier's check.

Quote :

"the ecm was unable to be adapted to the vehicle so we had to get another one. apparently the one we received was faulty and would not program to the vehicle."

Quote :

"there was a shorted wire between the ecm and the fuel injector on the engine, we have to re-wire the cable to correct it. this will also take care of the check engine light, but the fuel gauge is working, we put in $15.00 in gas in it and the gauge went up and the tech checked it out, he said it was working. i will try to have it out by the end of the day as best as i can, this is a pretty fair size job to be done. i will let you know another update by 4:00pom at the latest, if you haven't heard from me, drop me a line"

10/2/2008 6:43:57 PM

have you talked to other owners? do they have a similar issue? hell, i'm still not sure what the issue is really.

Quote :

"let it be known that something has to be causing these miscalculations."

that doesn't mean it can be fixed. if it's an inherited design problem from the factory then i dunno what you can do

10/2/2008 7:26:34 PM

So wait, are you datalogging a stock ECU calibration, or a chipped ECU? What is your long term fuel trim now?

I'll try to apply some of my experience tuning Hondata and other OBDII stuff. Try disconnecting the battery/resetting the ECU. Now what are your short term fuel trims during daily driving? They should be around +/- 5% if you do not want it to build long term trim. Short term fuel trim is built during closed loop operation as the ECU responds to o2 sensor feedback. Short term fuel trim does not affect open loop/WOT operation directly. But if the trim is more than +5% (lean condition) or less than -5% (rich condition) over a sustained period, you will begin to build long term fuel trim. Long term fuel trim affects AFR's under WOT/open loop in addition to affecting closed loop operation. It is how an ECU "learns" its way out of a tune, and why typical piggyback engine management systems (SAFC, e-manage) are tough to use on OBDII cars. That's how it works on Honda, Mitsu, and Mazda ECU's anyway. If this is an aftermarket/chipped ECU calibration and it is a decent tune your long term fuel trim should settle around +/- 2% if it is spot-on, or +/- 5% if it's a bit off. If it is just a stock ECU and no modifications I would expect +/- 8 to 10% max.

Can you post another log(s) file in .csv form? Reset the ECU, perform some drive cycles, and datalog rpm, throttle position, boost (if possible... do audi's have MAP sensor?), short term fuel trim, long term fuel trim, absolute load, and calculated load (if it lets you log both). Also check your readings for barometric pressure and mass air flow rate. Have you looked at all the pending codes and self-diagnostic emissions tests? Your sample rate appears to be at the OBD II minimum standard of 6hz... that log you posted has one sample every 1.1 second or so. You may get a faster sample rate if you log only one or two PID's at a time, but you will need to take more logs.

[Edited on October 3, 2008 at 3:16 AM. Reason : log lambda and commanded equivalence ratio too. they are both standard OBDII PID's]

10/3/2008 2:59:50 AM

I have more logs, I just don't know how much is useless redundant information. Plus they're months old. I'll try to grab the ones off my laptop today and if I drive to the beach this weekend, I'll relog. Thanks for the input.

http://www.elusivity.com/LOG-01-000-002-005.CSV
http://www.elusivity.com/LOG-01-111-115-003.CSV

[Edited on October 3, 2008 at 7:44 AM. Reason : .]

10/3/2008 7:41:09 AM

http://www.geocities.com/arghx/load_vs_MAP.xls

I went through the last log you posted (log 003) and I edited it down to a chart of absolute load vs MAP. Take a look at it. I'm not sure if VW has a quirky way of reporting MAP, but why the heck isn't your pressure sensor reading vacuum???? Make a chart of MAP vs Absolute load and you will see that it never reads less than 1000 millibars. Is that how every car reads, or is something wrong? You need to look into that further.

The log with the lambda values is hard to interpret because it doesn't have a very descriptive label. The one that says 7% all the way down could be your long term fuel trim. Maybe. It doesn't say. Column D or E in my Excel could be target lambda, and F could be measured lambda. I imagine the measured lambda value is reasonably accurate, as most VW's use the Bosch LSU 4.2 wideband sensor (common in most aftermarket systems). Your sample rate is really slow though so it's hard to interpret any lambda values under load. It would be nice to see a log of MAP, absolute load (column I in my spreadsheet, not column O, which is "calculated load"), relative throttle position, target lambda, measured lambda, and short term fuel trim in the same data set.


From SAE J1979 (entire SAE handbook is available at DH Hill on CD in PDF form btw)





most important thing to remember about calculated vs. absolute load is that calculated load never exceeds 100% and is correlated with throttle position, while absolute load is an actual measure of how much air the engine is pulling in.



[Edited on October 3, 2008 at 11:21 AM. Reason : normally MAP is reported in kPA, and under 100 kPA is vacuum, 100 is atmosphere, 100+ boost]

10/3/2008 11:06:27 AM

Quote :

"I'm not sure if VW has a quirky way of reporting MAP, but why the heck isn't your pressure sensor reading vacuum????"

no it should read properly with less than 1000mbar

check for vac leaks like i said before. i have a pressure tester if you need to use it.

[Edited on October 3, 2008 at 11:32 AM. Reason : ...]

10/3/2008 11:31:49 AM

http://www.elusivity.com/LOG-01-115-005-002.CSV
http://www.elusivity.com/LOG-01-115-001-003.CSV
http://www.elusivity.com/LOG-17-001-002-011.CSV

Those are the longer logs from 5/30 and 7/4. ^I need to, but I'm rarely with my car in Raleigh anymore. I was there today actually, but I had the company hybridz.

10/3/2008 3:25:39 PM

fix the vacuum leak/bad pressure sensor and get back to us, there's no point in doing anything else until then.

[Edited on October 3, 2008 at 6:40 PM. Reason : and use a pressure tester, the carb cleaner trick doesn't work nearly as well. Seriously.]

10/3/2008 6:38:48 PM

sorry for the change in subject, but I need to use a VAG-COM, or figure out how to unplug my battery and then plug it back in.

I don't know anything about cars. Can anyone help?

(Brief Description: 2000 Jetta 1.8T has EPC light come one and then Check Engine light and has recently been stalling, I think it's the MAF Sensor and another forum said to use a vag-com to reset the codes or unplug the battery and plug back in).

10/7/2008 3:19:41 PM

i read it's called limp mode

10/7/2008 3:21:27 PM

pm beethead, he runs a vw/audi shop.

10/7/2008 3:36:40 PM

^ thanks!

I'm gonna go ahead and try to drive it to Advanced auto parts, they can at least check the 'check engine' light.

10/7/2008 3:37:49 PM

yeah, they should be able to at least pull the codes. they can try resetting the computer by disconnecting the battery as well, but there's no guarantee it'll clear the code or the cel. just depends on what it is. even if it does clear, it might just come right back if you've got something wrong.

Jeepman (matt) works at the one on western. not sure if he's working today though.

10/7/2008 3:42:17 PM

responded to your PM. we can also datalog to check that the maf is working properly.


[Edited on October 7, 2008 at 5:45 PM. Reason : .]

10/7/2008 5:42:53 PM

I'm driving to knoxville and then memphis tomorrow. Which three blocks would be best to log there/back?

12/30/2008 5:21:18 AM

perhaps your ecu is metering fuel in liters instead of gallons?

12/31/2008 2:57:36 AM

didn't we already settle on the fact that you likely have a vacuum leak?

12/31/2008 3:03:59 AM