Lack of power- Just retrieved the car

[MaxRS6]

from the dealer. They replaced the manifold gasket and other seals. In addition, they replaced a Exhaust Gas Sensor.

When I push the pedal, sometimes the car takes off like a bullet. However; other times the car accelerates at a snail's pace (took over 5 seconds to go from 76 to 81). It feels like the infamous "limp" mode I"ve heard others describe. I had no issues with this prior to retrieving the car.

Can the exhaust gas sensor cause this type of behavior? I don't have a vag-com and thought I would ask you all for thoughts and comments with what I know to be limited information.

I've contacted the tech but he has left for the day and is to call me in the morning.

Thank you in advance for comments and input.

[Ebony rs6]

Is your car chipped?I just recently had an n80 replaced,plugs,trans fluid change, and what the audi dealership called terra-clean(was recommended as preventative maintenance),which supposedly is an injection service to clean out exhaust,and sesors of carbon.Now i have half limp mode.Sooo quiet exhaust and more pedal now for same result.My car is chipped and i think either the ecu needs a reflash due to new part, or aplugged cat or 2 when they did the terra whatever.What stinks for me is i'm having trub finding what brand is in my car.Maybe for you it is a bad seal thus air escaping which the turbos need.Please replyatou ucu

[DHall1]

Manifold gaskets? Which manifold? Intake or exhaust?

Do you know the tech? How good is he? RS6 tech?

Why was the manifold gasket replaced?

Why was the EGT sensor replaced?

If intake manifold.....you got a hornets nest of hoses and boost lines that were moved.


from the dealer. They replaced the manifold gasket and other seals. In addition, they replaced a Exhaust Gas Sensor.

When I push the pedal, sometimes the car takes off like a bullet. However; other times the car accelerates at a snail's pace (took over 5 seconds to go from 76 to 81). It feels like the infamous "limp" mode I"ve heard others describe. I had no issues with this prior to retrieving the car.

Can the exhaust gas sensor cause this type of behavior? I don't have a vag-com and thought I would ask you all for thoughts and comments with what I know to be limited information.

I've contacted the tech but he has left for the day and is to call me in the morning.

Thank you in advance for comments and input.

[MaxRS6]

Manifold gaskets? Which manifold? Intake or exhaust?

Do you know the tech? How good is he? RS6 tech?

Why was the manifold gasket replaced?

Why was the EGT sensor replaced?

If intake manifold.....you got a hornets nest of hoses and boost lines that were moved.


It was the intake manifold. Two separate dealers verified the manifold issue. The first dealer is local Audi dealer, and not a certified tech. Therefore, after their initial look, I took to my normal RS6 tech (2 hour drive). I had various codes and the diagnosis was a faulty gasket.

The tech is a certified RS6 tech and has done the work on my car since original purchase in Jan/04. They have done a good job in the past.

The tech stated codes were present that indicated a faulty bank 2 exhaust gas temperature sensor. Therefore; they replaced the EGT. They did this without pulling the engine and tranny to save a ton on labor.

It is odd- I can WOT from about 70 and and the acceleration is very slow, I then let off the pedal- put it back to WOT and it takes off with great acceleration. Sometimes it will take off on the first push or it can be on the 3rd or 4th push of the pedal.

I certainly appreciate your thoughts and questions. The tech should be calling me within the next couple of hours to discuss.

[hahnmgh63]

I think for a proper assessment you will have to get a Vagcom hooked up for code and or data logging. Of course it is most likely linked to the manifold repair so that could be many things.

[RS6-4dr911]

Could this be a simple as resetting the throttle position sensor? (owners manual, something like key off, key on, pedal to floor several times, hold your hand up in the air and rub your tummy,key off, start enjoy)

[DHall1]

Ok,

Makes more sense. The EGT does not need engine removal for R/R.

Your 70mph pull could sound like the ECU pulling back boost. It could be detecting slip in the trans.

Vag-com data log needs to be performed.


It was the intake manifold. Two separate dealers verified the manifold issue. The first dealer is local Audi dealer, and not a certified tech. Therefore, after their initial look, I took to my normal RS6 tech (2 hour drive). I had various codes and the diagnosis was a faulty gasket.

The tech is a certified RS6 tech and has done the work on my car since original purchase in Jan/04. They have done a good job in the past.

The tech stated codes were present that indicated a faulty bank 2 exhaust gas temperature sensor. Therefore; they replaced the EGT. They did this without pulling the engine and tranny to save a ton on labor.

It is odd- I can WOT from about 70 and and the acceleration is very slow, I then let off the pedal- put it back to WOT and it takes off with great acceleration. Sometimes it will take off on the first push or it can be on the 3rd or 4th push of the pedal.

I certainly appreciate your thoughts and questions. The tech should be calling me within the next couple of hours to discuss.

[MaxRS6]

too much boost is being produced and the waste gates are being opened. He has the car and is researching the issue.

:incar:I am torching around in a very light blue Ford Focus. While I"m somewhat fuming at the fairy color and car provided, I go through a drive thru and the girl goes off on how much she likes the car and color- and wanted to know the model year- LOL

[MaxRS6]

blow off valve. $150 part and a couple of hours of labor. I'll get it back next week and with any luck, I'll have the beast back in prime form.

Thanks again for everyone's input

[MaxRS6]

solenoid that controls the valves.

[V8weight]

You mean the N75 (turbo frequency) valve? This valve controls the wastegates. That would be the common link between yours and peisergs problems.

[MaxRS6]

You mean the N75 (turbo frequency) valve? This valve controls the wastegates. That would be the common link between yours and peisergs problems.

current diagnosis. Specifically, the solenoid that controls the valves. I'll know on Monday when they receive the part and test, and provide an update.

I certainly appreciate this forum and the invaluable information all of you provide.

[DHall1]

Well,

The basics are always N75 wastegate solenoid and 2 diverter valves (bov).

Then retest.

Gerry's problem was the wiring between N75 and ECU.

[mmaturo]

oddly this is the ONLY thing that has not failed on my car in 77K miles. hmmm, bet it breaks next week, as i have had the car home almost a full month.

[MaxRS6]

oddly this is the ONLY thing that has not failed on my car in 77K miles. hmmm, bet it breaks next week, as i have had the car home almost a full month.

have 7 or 8 rebuilt RS6's part by part.

[mmaturo]

have 7 or 8 rebuilt RS6's part by part.

add hyoctane and i will say hell yes. (I actually have had 7...yes 7 HVAC control units in my car since 28K miles). Seriously i think just everything inside my my engine block, (not so much everything attached to it), my radiator and inter coolers, and the drive shaft/rear differential are about it on original parts other than the frame/body panels, sunroof, and most of the interior...oops nope, i have had new front door interior panels too.

[peiserg]

add hyoctane and i will say hell yes. (I actually have had 7...yes 7 HVAC control units in my car since 28K miles). Seriously i think just everything inside my my engine block, (not so much everything attached to it), my radiator and inter coolers, and the drive shaft/rear differential are about it on original parts other than the frame/body panels, sunroof, and most of the interior...oops nope, i have had new front door interior panels too.

what happened to your hvac? i have had a code for a LONG time regarding a flapper valve in the hvac, but the car has been running absolutely great. an independant tech mentioned it was an a/c issue? I assume he meant one of the little motors that adjusts the vents of the a/c output to the cab.

[mmaturo]

I have circular posts going...i just replied to a thread from today about HVAC issues and it was the fact that it would not properly operate the 'flapper' valve or damper that allows the cooled air into the cabin. As the car ran the AC to get the temp that was inputted it would be fine till it reached that selected temp...at that point it would throttle back, the damper would close, and then unfortunately as the cabin warmed up again it would not reopen...so the compressor is running, the fans are blowing but nothing is coming out anywhere. Only happened after about an hour of driving so only caught it on the 3 months of summer (on above 75 degree days so rarely) we have in Chicago on long commutes or when doing a long road trip say to Florida. Unit after unit (it would be fine for a few months then same problem would happen...it still did it till the last one finally works correctly all the time.

So once it closed car had to sit for more than a couple of hours for it to work correctly again. When i would take it in they would let it sit so couldn't replicate unless they drove it for an hour...i finally told them to just leave it out in the parking lot on a warm day running for an hour...bingo.

[MaxRS6]

issue. However; the tech noted some vibration during the test drive and recommends the drive shaft now be replaced. ETA is now Wednesday to get the car back.

I'll certainly miss the Ford Focus they have me in at the moment..:)

[hahnmgh63]

How many miles are on the car? Is the car on an extended warranty as Audi would charge a fortune to replace the driveline.

[MaxRS6]

How many miles are on the car? Is the car on an extended warranty as Audi would charge a fortune to replace the driveline.

$1,300 for the drive shaft/parts and approximately $400 labor for install. I do have an extended warranty and I'm awaiting investigation/review to see if they will cover the repair.

[hahnmgh63]

Hopefully they will cover it. If it isn't covered a shop can pull it without too much work. I'm not sure about the RS6 but some of the older Quattros Audi wouldn't sell the center bearing and many of the parts separately but only the whole Driveline in one piece. I haven't checked out Vagcat.com to see if this is still the same. Some high end driveline shops can usually rebuild and balance them to as good or even better than OEM specs. If they are pulled apart for a new center bearing and joints, it is always a good idea to have it rebalanced.

[MaxRS6]

:rs6kiss:

The solenoid corrected the power issue, and the drive shaft (warranty covered- thank you Bruce) has removed some slight shaking that was going on during acceleration. It is a beautiful thing- and was a great 2 hour drive home from the dealer with a fully functioning beast