C5 allroad

A6 All/ S6 All
#481

Not a problem. Some times is extremely helpful to have someone with fresh eyes look at something and I will regularly conference with different people to see if I am missing something. That was one of the most helpful things that I learned from my mentor at the dealership. Even if I start to annoy people by asking questions on a seemingly simple topic.

Can you post the actual codes? I would like to see the P-code number and description.

The FI downpipes are the two piece design right? Like in the pictures online. It shouldn’t matter but double check that the front and rear portions are tight at the two bolt flange.

When you are checking the downpipe connections at the exhaust manifold it is important that the flared portion of the downpipes is correctly over the flared end of the exhaust manifold in addition to the six 13 mm nuts being tight. I am in the middle of a big project and had these parts handy so I took some pictures to illustrate my point. The exhaust manifold is on the left and the downpipe is on the right. To begin with the downpipes are flared to go over the end of the exhaust manifolds.


http://i284.photobucket.com/albums/ll37/Jimmybones777/SAM_2900_zpsi4cdt8fu.jpg

Ideally the flared end of the downpipe will sit flush against the end of the exhaust manifold like below.


http://i284.photobucket.com/albums/ll37/Jimmybones777/SAM_2901_zps8dyxmfv2.jpg

If the downpipe is cocked off to the side like below then that will definitely cause those fault codes/CEL because of the exhaust leak. In the past I have had S4s come in with the downpipe ever so slightly off that it would be sealed above a certain temperature because the pipe expands and then under a certain temperature there would be a quiet exhaust leak. It was frustrating to diagnose as a newbie tech too.


http://i284.photobucket.com/albums/ll37/Jimmybones777/SAM_2902_zpsjzncyzq8.jpg

Then the wobble triangle flange end acts like a compression fitting to hold the downpipes tight to the exhaust manifold.


http://i284.photobucket.com/albums/ll37/Jimmybones777/SAM_2903_zpshzdairhp.jpg

Hope that helps.

#482

The codes are vag 18628, 18630 - p2196 and p2198 (rich front) and vag 18528, 18530 - p2096 and p2098 (lean post cat).

The fi dps are the same two piece slide fitting as pictured, I think. Need to be under the lift and examine at the exhaust manifold to be sure. Will probably need to loosen up the entire exhaust system and refit everything to be sure it is all mating up proper.

Thanks again man. I really do appreciate the help and advice.

#483

Another data point of interest is my front O2 voltages are consistently reporting 1.4+ volts. All the way up to 5 under load/acceleration. Then rarely are ever dipping below 1.0v. That certainly seems odd and curious as to how/why this just surfaced. Weird. Car is up on lift and exhaust components are being checked over.

#484

Edit: 2x and because wideband, duh.

Another thing I am noticing is my maf readings are elevated when my hvac system is on at idle. When on maf is high 5’s. When shut off, high 4’s.

Which, makes sense due to slight load increase?

#485

Sent JHM some O2 sensor logs to get their opinion. Channels 1, 33, 36

#486

Sent JHM some O2 sensor logs to get their opinion. Channels 1, 33, 36

#487

yes because wide ban.

Also yes. When you turn on the AC the compressor runs and that puts a big draw on the motor that draw or load requires that the motor work harder but not nessessarly request more rpm. More load more GPS from the maf.

#488

Still no solution to O2 codes. F it, still took the trip to Montana. Car did fine.
https://uploads.tapatalk-cdn.com/20170213/ba75bf0b4fc8328ca8bf125aa7ea5981.jpg

https://uploads.tapatalk-cdn.com/20170213/15f4821b492b8b1ef98571c94121a160.jpg
view from deck
https://uploads.tapatalk-cdn.com/20170213/1792570e693ce58657e36f19fa0dda90.jpg
bison in yellowstone
https://uploads.tapatalk-cdn.com/20170213/faf03d32cd688ed166860ef62c8c002e.jpg

https://uploads.tapatalk-cdn.com/20170213/3c0eeedf4a091e3b8f397da0fa01aa84.jpg

https://uploads.tapatalk-cdn.com/20170213/6cfbc7b78a12dd68c2e5e34e474f34b6.jpg
old faithful
https://uploads.tapatalk-cdn.com/20170213/efd4fa44ac97826016eda6b6e9f930d2.jpg
unique mode of transportation
https://uploads.tapatalk-cdn.com/20170213/d9ca1ee7ed2a9ef8fb5c72914edca119.jpg
buddy double ejected. Ended up 50 yards down the slope. Lucky not hurt seriously.
https://uploads.tapatalk-cdn.com/20170213/7b42c807d19ca54b62adafcdf8560fc1.jpg
for reference. Thin cover in area he took the spill. We were flying and he didnt pay enough attention. Rocks stopped him dead in tracks and he went tumbling head first.

Buddy is a pretty damn good photographer and sent me this capture
https://uploads.tapatalk-cdn.com/20170213/1af5852fec7f73881639b691d9b641a8.jpg

Great time!

#489

beautiful scenery…

#490

Small update, been asked to remove rear 02 jbungs and replace with standard 02 bungs for rear sensors.

#491

Like the ECU isn’t seeing enough exhaust flow for the rear O2s.

Great pictures by the way!

#492

Thats what i am thinking. Differenc readings are low.

Thanks. Was a nice trip. Could find a way to make a living and stay up that way. Beautiful country.

#493

Been a while. Have not hacked up my downpipes yet. Seems a little silly to jump through that hoop seeing as though if they weren’t designed that way for reason, why would it fix my issues.

For shits and giggles (pretty much the story of this car at this point) I thought why not just disconnect the rear 02’s and see what my fuel trims do. Of course, I get open circuit fault codes for rear 02’s. Fault codes are least of my worries since the car hasnt opearated without one since day one of getting it back over 2 years ago. Lol! I want to test my own theory and see how this effects my fuel trims. Well, glad to report they are as in spec as they have ever been. Instead of sky rocketing rich within about 50 miles, what do you know, they start lowering inline to spec. After 120 miles, block 032 reads -2.3%, -2.4% STFT and 5.5%, 7.3% LTFT. Before, LTFT would be so out of whack in under 100 miles, tripping that BS post cat too lean code that the car would just be dumping fuel to compensate from incorrect rear O2 “feedback”.

Now, I may be way off in my understanding of the situation, but my vcds does not lie and my fuel trims are ridiculously better after simply disconnecting rear 02’s. Are there any red flag warnings to be aware of running the car like this long term? If my fuel trims are better, aren’t I better off?

Makes me wonder why they simply are not disabled and coded out? I mean they sure as hell were not helping my gas mileage one bit based on my logs and vcds feedback. In fact, with them disconnected, my gas mileage and trip computer estimates, and instant gas mileage are noticably better. So frustrated. Luckily, I don’t have smog testing here so not concerned about that aspect and have time to keep monitoring my suspicion that there is something fishy with my ecu tune.

#494

Great results and great idea.

you have proven what a lot of us have seen ourselves and thats that the rear 02s play an active roll in helping the LTFT and are indeed for better fuel mileage. Something seemed to be wrong with these o2s from the start as thats when this issue popped up. Like jimmy said it looked like either there was something up with the 02s or they genunily were not getting enough flow across them. Either way the way the 02s were reading were causing fueling interuptions.

Now that the car has a good signal and its only reading off the primary 02s there is no interference. You see this kind of issue with people with 02 spacers or J bungs on the b7 S4s and since the allroad shares that version of the ECU this would make sense.

you asked why wouldnt the rear 02s be coded out and are you better off. Well your better off then you were before thats for sure. but the real question was… was it the 02s or was there really an issue with the exhaust. Again we see exhaust issues cause all kinds of issues with the b7 cars so it could have been a combination of both.

You kinda proved that there isnt anything wrong with the ECU tune. You removed a sensor that is readying wrong one way or another and once that was removed the car runs correctly. Remember the ECU is only responding to the feedback that the 02s give and i would have to go back and read the entire thread but from what I remember i your thread the car was ok until the 02s got replaced. and from the voltages you gave after logging the car that would deffinitly put a car out of whack when you look at it.

I other than a code I dont see any issue with not having the rear 02s plugged in as they seemed to for whatever reason cause more harm then good. I would drive for a few weeks put some miles on the car and then see if you have any fuel code issues and then go from there.

Now that you have put these results out there this all makes sense. If the rear o2s are reading wrong for whatever reason and they are getting a lean readying that will cause the car to add fuel. When the car adds fuel baised off the rear 02s the font o2s are going to read rich becuase there is no reason to add more fuel.

#495

Ya, issue was poorly fabricated/braced down pipes/flex joints. They basically fully separated after leaking for who knows how long. Suspect from day one. New flex joints and beefed up bracing and viola, no more codes, also much smoother and cleaner exhaust note. Pretty disappointing considering I had been chasing my tail over this issue for far too long and it was exhaust leaks all along…tap, tap, tap, tap, tap…lol. Once they full separated the car sounded like an exhaustless 69 camaro.

Moved back to sea level and 93 octane and aside from heat soak, the car is finally running strong. No codes and full readiness for months…sigh

#496

Thats great to hear. Jimmy called the exhaust quite some time ago so good for him to have gotten that right. and even better that you got it fixed. This is a great build and a fantastic car. Now you can enjoy it more issue free. And when you have had enough look into the state 1+ then you can get an intercooler so you have to worry less about heat soak.

#497

Hey man, unfortunately fourings aka 4rings2turbos is parting out his sick allroad. I suggest you jump on some of that goodness:

http://www.audizine.com/forum/showthread.php/791033-fourings-allroad-partout

#498

Ya, I think I am done with spending $$$ on modding this car. Just going to keep it well maintained and in good shape and be done with it. Might pick up some oem replacement stuff from him. I’m fairly local so easy to take a few things off his hands.

Today was able to replace my rear hatch struts (easiest thing on car to date), inner driver side headlight locating tab (major pita), and had a major growling passenger front wheel bearing done earlier this week. What a difference. Been driving around with that for a longer time than I care to admit. Thought it was bad tire wear, but once I threw evenly worn winters on and it was still howling at me, knew it had been the wheel bearing going all along. Nice and smooth and quiet again.