Hey! I've been pulling my hair out on this one the last few weeks and finally have resorted to asking the greater Audi community if anyone knows what's going on with my car.

To start, I semi recently (last year) bought this car and it ran mostly fine, but being an older S6 I knew there would be some things that likely needed addressed (as well as a few oil leaks). So, shortly after buying, I did the following (~88k miles)

• Intake manifold flap delete
• Intake valve carbon clean
• Valve cover gaskets, Oil filter housing gasket/o-ring
• Spark plugs
• Engine air filters
• Throttle body clean
• Accessory belt
• Oil change

I did all of this service at once (since so much has to come out to carbon blast the valves). Before doing this work, there was no check engine light or ESP fault.

After putting everything back together, the CEL and ESP lights are now on, the car feels very low on power, and it smells like it's running rich. Full VCDS scan is attached if needed.

I've already replaced the MAF/Intake Air Temp sensors to no avail on that code(s) since it seemed easy. If it is relevant, the TPMS on this car was disabled a while back through VCDS and has the fuse pulled (I know how to reverse this if needed, but would prefer to avoid buying 5 tire pressure sensors if I can). I suspect I may have put the intake manifold flap motors back on incorrectly causing the manifold flap faults. For the rest, I can really only think I left a plug (or multiple) not fully plugged in or something when putting everything back together, because I have no other notion of what the intake manifold would have to do with causing all these ABS/ESP lights. It's also possible I'm reading more into this than I need to be and this is instead a bad coincidence. Regardless, I'm looking for literally any course of action to resolve this because the car is otherwise great and I miss it. Thanks all in advance for any thoughts.

 

EDIT: Removed comment about replacement parts

Any chance you adapted the Throttle bodies when you finished all of this work?
Under each of the engine modules go to basic settings and adapt the TBs Not sure this will help, but damn sure can't hurt.

In all of the scans I have done, I have never seen this message, That doesn't me much, but is interesting
Under Trans
1 Fault Found:
006231 - Load Signal
P1857 - 001 - Error Message from ECU

As for the voltage issues, especially this one,
Under Engine II
005634 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
Freeze Frame:
I am thinking you have a loose connection somewhere.

As for the flaps, Personally, unless They are broken in several places, I am against removing or gluing them in place, they are there for a reason. I also realize that sometime you just don't have a choice. I was lucky and only had one broken spot and was able to JB Weld (Our favorite) them back together.

I would start by going to each module Engine 1 Engine 11 and engine other 31 and manually clearing the codes.

 

I did not adapt the throttle bodies but it is worth a shot. Would have never thought of that, so thanks.

As for the loose connection, I'll give every plug I may have touched a check.

My flaps were in rough shape. The cars supposedly run fine without them as evident by numerous other people who have done the flap delete, so I suspect I messed up elsewhere. It's either the delete or a new $4,000 manifold. Easy choice IMO.

 

You will loose torque on either to top end or bottom end depending on whether you remove or glue them in place. I think the longer runners will cause loss at the top end and the shorter (removed) will affect the bottom end.
Not just plug connectors, but ground connections as well. There are more than a couple you need to be sure are tight. 2 that I can think of are just in front of the HPFPs

Any time you do anything to the TB, they need to be adapted.

 

I have been driving for years with the TPMS light on for years, I'm old enough to remember when cars were not equipped with TPMS sensors and figured out myself if I had a tire with low/no air pressure.
When I had to replace my tires, I had inquired with Costco if they had replacement TPMS sensors and they told me that they did not offer them for my Audi but their scanner was able to tell me which sensor was bad.
I thought of ordering new sensors and have them replaced the next time I needed new tires but was so use to not having that feature I left them alone.

 

Just an update, I adapted the throttle bodies and cleared all codes. I also checked both of the ground points by the high pressure fuel pumps. I also triple checked all the plugs on the front of the intake manifold as there's quite a few of various colors that could theoretically be swapped around. This cleared a couple of codes, but not the MAF, Intake Air Temp, Intake Manifold, or P1602 voltage codes. The MIL and ESP lights are still on as well.

Any idea where else there may be a ground for the Intake Air Temp sensor? That by itself can/will trigger the limp mode and ESP stuff. The flap delete I know caused the intake manifold codes and needs tuned out, so that's less of a worry.

 

Pretty sure the Air temp is in the MAF, so I would be looking at them.
You can use VCDS to monitor the values that the sensors are seeing. As for the grounds, get a copy of the wiring diagrams from eRwin.

 

I know the IAT sensor is part of the MAF. I've replaced the MAFs and still get the code. They show -40 degrees constantly on VCDS so there's gotta be a short somewhere I think.

 

Also, can you elaborate on what you mean by "get the wiring diagrams from erwin"? Is that member in the forums?

Thanks for the reply btw. Anything is appreciated

 

Sorry, eRwin is the official Audi document storage.
https://erwin.audiusa.com/erwin/showOrderFlatrate.do
create an account and buy the one day subscription go in and down load everything you can find on your car.