papyrus

So as a followup to my earlier thread trying to find the cause of my fuel-trim mult too-rich codes...
I've now replaced the o2 sensors in addition to coil packs, plugs, maf, etc. Per my earlier thread (search "ape$hit") a last hope is EGT sensors. Running some searches, I see people report codes around these when they fail. I have no such codes.

1) Does this completely rule out the possibility they are shot?
2) assuming no - any other way to diagnose them? is there a register I can monitor with vag com to see the values the EGT sensors report? Any normal/bad behavior?
3) If I do decide to replace them, any how-tos - doable sans lift? Where can I buy them (only audi?)?
4) thanks.

DxC

when my EGT sensors were bad, it threw a code.
also when you would go WOT, at 4k RPM it would buck real HARD and cut fuel.

replacing them ... the passenger side is pretty straightforward and easy. the drivers side is a PITA!! i got to it on a lift going underneath near the turbo with a wrench i had to grind down to fit ...

there is a write up in the tech articles section of this site ...

oh and ECS has them, they are expensive for a sensor!!

HdiaS4

i guess depends on the problem but if your egt is reading too hot wil make the car run rich so the temp cna go down.

egt are abou $180 each on ecs, same for both sides.
034 EGT temp bank 1
035 EGT temp bank 2
here is a quote from edyjun site
EGT - Don't let these go over 980 deg C, at those temps, the EGT sensor will trip, it only works in a small range between like 945-1045 deg C, and if "tripped" it will signal the ECU to dump fuel, richening the mixture and reducing the EGTs. You can read temp using the O2 sensor temps, or by installing an actual EGT gauge

Avantgarde

I am running Stage 3- (GIAC 3- software). I started throwing the same CEL codes - Rich on both banks.

I spent literally all summer tracking down some PITA small boost leaks thinking that this was the problem. When i finally got the boost squared away i still throw the codes.

I am replacing both EGTs this weekend, but hate to spend the time and money if they are not the problem. Sorry this isn't helpful - but if you could keep me posted.

I guess the point of this long response is to say that FWUW, I am assuming that my EGTs are bad without the actual EGT code.

Good luck.

papyrus

I dug through the vag files looking for some codes to monitor EGT before reading followup posts this morning. I found measuring block 112 in vagcom which has bank 1 and bank 2 EGT monitored. I set it up and monitored them all the way into work. 945 deg C FLAT all the way to work, up and down RPM etc. Two options:
1) I'm reading the wrong codes or a block that isn't valid on my car/ECU
2) The sensors (or anything else) are shot indeed and reporting a flat minimum value at all times, and I'm turning the corner towards salvation.
Any comments? Searching more in the vag files this morning, I only see one file with "exhaust gas temp" and "Audi A6" (yeah it's not an S4 - 2.7t manual though, so same thing) in the same file:
078-907-551-AZA.lbl
The only line explicitly mentioning 034 and 035 comes from an unrelated label file - Audi A2 I think. Anyway I assume 'measuring block' 112 actually reads values 034 and 035 to fill in fields 1 and 3, but either way it really seems to me like I'm looking in the right place. Can someone else run block 112 to see if you get real (changing) values here?

Avantgarde

Might make sense to repost the request for 112 logs - i am sure someone will help us out with a healthy car here.

Feel free to drop me an email on this - maybe we can solve it together.

Thanks for the update!!!

papyrus

I gave it a shot and put up a separate thread requesting it. On a separate note I also monitored the 043 and 044 values, and they are a different ballgame. I haven't researched it yet but hazy memories of reading posts and logic combine to make me think these readings are in a different location than the 112 - before v. after the cats , turbos, or both. 043 and 044 were *identical* (thought left and right, but identical values are too lock-step to be true) and ranged frmo 350 deg to about 790 if I remember correctly - well correlated with what you would expect - more exploding gasoline = more heat.

papyrus

I found someone else's 112 logs.. flatline 945s. looks like I've learned absolutely nothing.

https://forums.audiworld.com/performance/msgs/74045.phtml

it might be cheaper and more fruitful to code something that just wipes all the DTCs every 5 seconds! How long are these damned cars going to last anyway?