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Author Topic: Coding out intermittent egt faults  (Read 24561 times)
Mechsoldier
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« on: February 16, 2016, 04:49:59 PM »

Had a friend ask me about coding the egt out today, I tell customers no normally, but he's an Audi tech so I was less apprehensive about it blowing up.

At first I codes out cdatr, cdats, and catr, and obviously it just fell on its face because I didn't realize I had to change the fueling now that it isn't hitting the threshold.

His sensors actually function fine the majority of the time, but I guess very intermittently, talking every couple weeks throw an implausible signal fault.
I ended up only changing cdatr and cdats to zero,
Which resulted in me being able to even unplug tje sensor without a fault, indicating it's ignoring the diagnosis of them, but as long as I leave them plugged in the car drives great.

Anybody ever use this as a work around for somebody whwre the egt seem to be properly functionING 99.9 percent of the time?

Like I said he's a master audi tech so he can monitor this from now on, on his own, and I'm awaiting feedback, but it might be good for people whose cars seem to exhibit it little or no symptoms of bad egt but for whatever reason are throwing a fault.
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giles92
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« Reply #1 on: February 16, 2016, 05:28:58 PM »

year make and model or the type of file your using?
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Mechsoldier
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« Reply #2 on: February 16, 2016, 06:55:58 PM »

year make and model or the type of file your using?

I used an m box file
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giles92
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« Reply #3 on: February 16, 2016, 07:41:53 PM »

Have you tried this? per s4wiki:
You shouldn't have to touch these, but are included here for completeness:

CLAATR - Error class exhaust gas temperature regulation
CLAATR2 - Error class exhaust gas temperature regulation bank 2
CLAATS - Error class exhaust gas temperature sensor
CLAATS2 - Error class exhaust gas temperature sensor bank 2
Also check your other cdatr catr cdats hex location against the ones posted on s4 wiki. Ive had success using this process
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Mechsoldier
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« Reply #4 on: February 16, 2016, 08:29:08 PM »

I had no problem removing the sensors it's just then don't you have to modify the fueling? He wasn't having issues with the sensors functioning just an intermittent code. What I did seemed to fix the problem is what I'm saying
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giles92
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« Reply #5 on: February 16, 2016, 08:42:33 PM »

The ecu will now run off of calculated egts extrapolated from the o2 sensors. If you wanna mess around with the component protection fueling (bts) more read the stage 1 551m community thread. Youll need to adjust fbstabgm axis and tabgbts described in the LAMBTS category. If your giving the car a tune i would also change lamfa to cover fueling. That can be found in the community thread as well.
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prj
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« Reply #6 on: February 18, 2016, 12:24:10 AM »

The ecu will now run off of calculated egts extrapolated from the o2 sensors.
Bullshit.

OP:
CATR switches off actual enrichment, probably the most important one.
Also, you might want to adjust BTS so that it keeps EGT's in check.
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Mechsoldier
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« Reply #7 on: February 19, 2016, 04:41:38 AM »

The ecu will now run off of calculated egts extrapolated from the o2 sensors.
Once again, I ONLY turned off the diagnostic portions. So I did NOT disable the CATR. At first I did, but that isn't what I intended. And yes it fell on its face and I realized I couldn't do that without messing with fueling.

So I ONLY turned off diagnostic. So sort of.like when you turn of cold light diagnosis of the tail lights to put on LED so that it doesn't check resistance. I didn't disable.the signal. I only told it ignore signal plausibility. And sensor resistance check.



Bullshit.

OP:
CATR switches off actual enrichment, probably the most important one.
Also, you might want to adjust BTS so that it keeps EGT's in check.

Again, the car is NOT ignoring the EGT. In my opinion this is a much safer way to go about "disabling" the egt from people that are getting egt faults. Especially if the car is running fine as verified by a wide band or something.

And as far as the tuning faq. I actually own Kess v2 and ecm titanium. The real registered versions. So a lot of the things are defined in their drivers. And actually they'll make any drivers for me I want.

So to reiterate again, if you disable CDATR and CDATS, and leave CATR alone, the vehicle will no longer throw any egt faults for the signal being implausible, nor for the sensor resistance being faulty,  and the ecm will still use the EGT for fueling calculations.I have the innovate motorsport wide band, and I also have a thermocouple with a testing meter so I can verify fueking and egt independently.
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ddillenger
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« Reply #8 on: February 19, 2016, 05:06:56 AM »

You need to learn to differentiate between when the egt model is used, and when the egt sensors are used. Your statement was incorrect.
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prj
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« Reply #9 on: February 19, 2016, 09:35:04 AM »

So to reiterate again, if you disable CDATR and CDATS, and leave CATR alone, the vehicle will no longer throw any egt faults for the signal being implausible, nor for the sensor resistance being faulty,  and the ecm will still use the EGT for fueling calculations.
You're wrong. Not surprising if you use ecm titanium lol.

Here is how it actually works:
1. EGT sensors are used only in the ATR module, which is a closed loop controller. The target is a fixed "never exceed" value. The feedback comes from the EGT sensors. The control parameter is lambda. The more EGT, the lower the lambda is driven, to control the EGT. BTS runs off of simulated EGT's that has no connection to EGT sensors whatsoever.
2. When you disable diagnosis, what happens is, when the EGT sensor errors out, the value momentarily jumps to maximum 1000+C and ATR will fully enrich down to the flammability limit. It will not recognize it as a fault condition and just drive lambda into the ground.

Thus the car will intermittently puff black smoke at totally random times and bog due to the super rich lamdba.
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vwaudiguy
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« Reply #10 on: February 19, 2016, 02:04:44 PM »

You're wrong. Not surprising if you use ecm titanium lol.

Here is how it actually works:
1. EGT sensors are used only in the ATR module, which is a closed loop controller. The target is a fixed "never exceed" value. The feedback comes from the EGT sensors. The control parameter is lambda. The more EGT, the lower the lambda is driven, to control the EGT. BTS runs off of simulated EGT's that has no connection to EGT sensors whatsoever.
2. When you disable diagnosis, what happens is, when the EGT sensor errors out, the value momentarily jumps to maximum 1000+C and ATR will fully enrich down to the flammability limit. It will not recognize it as a fault condition and just drive lambda into the ground.

Thus the car will intermittently puff black smoke at totally random times and bog due to the super rich lamdba.

Does the ecu use any feedback from the 02 sensors to arrive at the calculated value?
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« Reply #11 on: February 19, 2016, 02:38:40 PM »

Does the ecu use any feedback from the 02 sensors to arrive at the calculated value?

No.

I think that misnomer started from tabgm being referred to as "temp at O2 sensor", then it gets regurgitated as "O2 sensor temp". Now it seems people think the O2 sensor is reporting temps.

It's mostly load, rpm, and airflow, then corrected by target lambda, ignition angle efficiency, etc

Edit: assuming you're referring to ATM, prj's text you quoted was ATR specific
« Last Edit: February 19, 2016, 02:40:24 PM by phila_dot » Logged
giles92
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« Reply #12 on: February 19, 2016, 03:33:01 PM »

The ecu will now run off of calculated egts extrapolated from the o2 sensors.

I didnt mean the o2 would be measuring the temp but that the ecu would be calculating a theoretical temp in there based on ATM. I didnt describe it in the best way, I understand. I figured the o2s and a few other inputs were what was used to come up with the exhaust temp model. I see that its more iat, load and rpm based. Thanks for correcting me.
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ddillenger
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« Reply #13 on: February 19, 2016, 03:57:42 PM »

Ignition angle.
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nyet
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« Reply #14 on: February 19, 2016, 04:00:42 PM »

I blame the wiki: it says something about removing the O2 requires fixes to the "EGT model" which is a misnomer. It should be the "O2 sensor temp model".

I'll fix it time permitting... or maybe dd will beat me too it Smiley
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