Eric Vermeire

I finally got around to changing out the circuit board on the driver's side EGT sensor. Not that bad, I kept the probe installed and just working over the middle of the engine. I was able to clean out the goop using a small slotted screw driver and patience.

In the end, my engine RPM fluctuations are the same, so I am not sure if I didn't solder the EGT sensor circuit boards in well enough or it is something else. The audi dealer originally diagnosed the EGT sensors as the problems, so I feel I need to just spend the $600 for new sensors and another $400 to install the driver's side (local mechanic).

AllWorld

Did you use the replacement circuit boards from Poland? Just do both sides with those. You have any codes/service engine light?

Eric Vermeire

Yes I did replace with the circuit boards from Poland. I don't have any service warning lights on my dash, but there were codes that were detected with scanner by my local mechanic and the Audi dealer. At this point, I am thinking that I didn't do a good job of soldering or maybe the probe is bad.

AllWorld

you don't have your own vag-com. When you clear codes with a regular scanner or even correct problems with the car and the light goes out - there are codes that remain. perhaps this is what they saw when they got codes even tho your service engine light was not on. they should be noted and cleared and see if it comes back. not sure if poor driveability would come from egt sensors though.

Eric Vermeire

Sorry about the very slow reply. This has been an ongoing issue. I ended up having the EGT sensors replaced by my local mechanic. The EGT sensors were purchased from the local audi dealer ($700) and another $300 in labor to install and still the same symptoms. Before I go and say all is bad after one week of driving with the new EGT sensors, my gas mileage improved 2 miles per gallon and I haven't had any warning lights. But the fluctuation in the RPMs at sub 3,000 RPM in 3, 4, or 5th gears is still persistent. I can avoid most of the engine RPM fluctuation via manual shifting and keeping the engine RPM about 3,000 RPM.

NOTE: I also had the transmission fluid replaced (5 liters) with audi OEM fluid and there were a bunch of small metal shavings stuck to the magnets in the transmission pan. But my mechanic said there wasn't any brass shavings. That transmission has about 110,000+ miles since being serviced. The transmission does shift smoother, but....I now the transmission isn't doing so great as some of the shifts are abrupt and at times when going downhill and turning right at about 10 miles per hour, the transmission will not engage for a couple of seconds.

Eric Vermeire

In the end the problem is my torque converter. I ended up paying $1,200 to have my local mechanic replace both EGT sensors with new Audi factory ones. I have my old sensros with the new Czech Republic circuit boards. I only kept one of the original circuit boards. I should have kept them both. Either way, I am am selling the old sensors for cheap on Ebay.

https://www.ebay.com/itm/11303361797...84.m1555.l2649

Adam's Dad

That's too bad you had your EGT sensors replaced! I'm (not) surprised Audi would recommend that as a fix for an RPM fluctuation problem. Knowing these cars, my first thought when reading your initial post just now was a transmission issue.
I'm sorry I wasn't here to see this thread earlier because I would have strongly reiterated what 5v/cyl said about bad EGT sensors only causing low boost and a richer fuel mixture.