You're mostly right about that, if we're talking about possible issues with EGT sensors and ECU's reaction to it. Apart from that accented part.
It does "something". It does enrich badly when your EGT shorts out. You keep insisting that you did stuff right when clearly that is not the case.


I can only quote prj here for great justice.

Honestly I'm not claiming to be omniscient or know everything I'm nowhere near the best tuner in here, a but I am good at diagnosis, and I am a dealer trained VW and Audi master technician as well. I merely wanted to share something I found out that may work for some people, and despite the fact that I've seen the car and logged it, there's people telling me what I'm saying is impossible and its not. The questions I post are about ecm tuning which I still have a ton to learn about. Telling me that because I know about ecm disgnosis, I shouldn't need to ask about tuning, isn't really true. One of my main sourcs of income is answering questions for people about diagnosis on websites online. Doesn't mean i know how to tune a car.

People are making the assumption that whatever is going on with the signal that is causing the fault is either not the ECM to enrich at the correct time, telling the ECM to enrich when it shouldn't, or that it definitely will do so at some poiny. Without seeing what it's actually doing, which I have, that's not really necessarily true.

The only thing that I'm claiming, is that the ECM pays attention to the EGT signals all the time, and therefor it's possible for the ECM to throw a fault for the EGT signal being out of whack even if the problem with the signal is that it's reading funny down at lower voltages well below the enrichment threshold.

It is definitely possible for a sensor to read incorrectly at one part of its range and not others. As I stated I've seen coolant temp sensors that will start out at 44 degrees and read fine until it hits say 72 degrees then drop off to -40 degrees and then start reading Fine Again all the way to full operating temp, I've even seen them do that on the instrument panel side but not the ECM reading side. I seen fan switches that will turn the fans on at 25 degrees celcilus, then the engine gets a little warmer they shut back off and then they get back on again at the proper time. I'm not surmising that it's possible. I've seen it 100 times in the course of working at the dealer and in my own shop over the past decade. Ive had customers decline the repair because they don't have the cash and seen the car for years after that still functioning the same way. Should it be replaced because it's malfunctioning? Probably, but is a fan switch that turns them on from 30 to 35 Celsius. Then shuts them off and operates properly
from 85 to 110 Celsius going to cause an issue with over or undercooling? No.

The assumption that the problem with the EGT signal is incorrect in the operating range that deals with enrichment fueling is incorrect. The assumption that it's necessarily going to degrade further and begin to malfunction in that range down the line is incorrect. And that has nothing to do with tuning at all. That is vehicle diagnosis related.

So, I'm not saying I'm even good at tuning at all, but I do know how sensors function, what the ECM is looking at, and what can cause a fault.

The only claim I'm making in this thread is the following.

The ECM looks at the signal and resistance of the EGT sensors at all times. It only actually does anything in response to that signal is if the sensor voltages crosses the threshold for enrichment per the setting in the ECM. If the EGT sensor does not read in the correct manner or the resistance of the sensor changes, then the ECM throws a fault. The ECM throws the fault regardless of whether or not the malfunction occurs at a temperature range that the exhaust is at idle, or if it's at a temperature range consistent with moderate throttle freeway cruising, or full throttle running lean as hell with a bad fuel pump. So if the signal malfunction is happening at a very low temperature where the ECM only pays attention to the signal for the purpose of signal diagnosis, but functions properly in the temperature range that deals with enrichment fueling, it will not cause any issues with fueling.

Will it get worse some day and start to malfunction in a range of temperature that could cause misfueling? Sure, but will it DEFINITELY? No. Will all EGT sensors fail in this manner? No. And will an EGT sensor that's malfunctioning below the temperature range used for enrichment fueling cause a fault, but not effect the entirichment strategy if you disable the signal diagnosis. Yes.

Again. You absolutely shouldn't do this to a customer car, but if it's your own personal car, and you can log the air fuel ratio or you have an air fuel gauge with a wideband installed, and can verify the Afr is correct, then fuck spending 600 dollars on EGT sensors.

Ok I'll check it out. I gotta see if he'll let me borrow it to weld in a bung. I know how to admit if and when I'm wrong and do my due diligence.

I can tell you with almost 100% certainty that if diagnosis is masked and CATR is enabled, if the EGT sensor reads enough to activate enrich, you will see enrichment on ME7

I could be wrong, of course.

You're not wrong obviously.  We ALL know this to be a FACT from much testing logging and experience that what PRJ and the FR says is true and the OP is wrong.

What the OP did and his assumptions because he has an "audi tech" that knows how a car is supposed to "feel" is laughable at best.

3 pages of nonsense for a basic part of the ECU's functions being debated is crazy.  Alone the fact that he hasn't taken any logs to see this for himself is enough to end this thread, never mind having it bumped after months.