Are my CAT temps too high?

[quietcropduster]

Has anyone ever done any logging on The Torque Pro app and or vcds of their catalytic converter temperatures? While cruising versus a wide open throttle pull etc?

While on the highway I'm around 1100 or 1200 consistently with cruise control turned on.

If I do a wide open throttle pull to about 100 miles per hour and Max is at about 1750 but comes back down quick.

Currently on EPL stage 1 tune. I have a sneaky suspicion my CATs are at the very start of being on their way out. Anytime I flog it past 3 RPM with my windows down I can smell something that smells like exhaust, not sulfur. My friend and I didn't exhaust leak test no exhaust leaks. Two other local guys with ironically the same tunes as me but stage 2 don't have this smell.

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[LocoLobo]

That's a good idea on checking the cats out, i've been wondering about mine for a bit. I'll see if I can figure out the datalogging in VCDS and get you my results. No good place around here for 100+, but I can get some high RPM readings and 80mph cruise and see how they compare.

[PenttisHSR]

The problem is that the EGT temps are a calculated value, there are no actual temps.

See discussion here...... .https://www.audizine.com/forum/showt...t-s-Talk-EGT-s

[MSq5]

The problem is that the EGT temps are a calculated value, there are no actual temps.

See discussion here...... .https://www.audizine.com/forum/showt...t-s-Talk-EGT-s

It's really not a problem. The calculated value is useful. Almost no OEM cars, regardless of make or model, have actual exhaust gas temperature thermocouple probes in the exhaust manifolds or downpipes. Such probes are fragile and usually are limited to automotive engineering or race engine building shops.

The calculated values obtained from the wideband pre-cat sensor will be pretty close.

[PenttisHSR]

Problem is that those of us who came from the B5 S4 had 2 actual EGT sensors.

[fitzydude]

Switch to Celsius and I think those temps are about where they should be.

Here is a thread where I reference my cat temps:

https://www.audizine.com/forum/showt...ight=Cat+temps

[SCHOUGY]

Shit, I'm hitting 1100C per side on DP. That's 2012F.

[quietcropduster]

Shit, I'm hitting 1100C per side on DP. That's 2012F.

Damn that's high lol

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[MSq5]

Problem is that those of us who came from the B5 S4 had 2 actual EGT sensors.

Why is this a problem? Can you produce data that the calculated values are unreliable?

As to absolutes, there may be variations. Probably varies based on your monitoring software and different calculation algorithms. I have not logged calculated EGT on my engine, so I don't know what is the norm for different operating conditions. Maybe someone here has and can post values, especially on a long run in a higher gear. Values on the other thread vary depending on monitoring or logging device (P3 versus VCDS). It is probably the delta between cruising value and sustained WOT value that will be useful.

[bhvrdr]

Why is this a problem? Can you produce data that the calculated values are unreliable?

As to absolutes, there may be variations. I have not logged calculated EGT on my engine, so I don't know what is the norm for different operating conditions. Maybe someone here has and can post values, especially on a long run in a higher gear.

I would say they are pretty reliable. Accurate...i cant say but generally pretty reliable i that I have seen corresponding increases in them as the boost went up. When I got to a 3.5 pulley ratio the EGTs scared me and the heat from it melted the SC belt. I believe I saw upwards of 1225C on a 3.5PR. I've seen 1050c to 1100c peaks on all 10 audis i've owned during the past 14 years.

Mike

[MSq5]

I would say they are pretty reliable. Accurate...i cant say but generally pretty reliable i that I have seen corresponding increases in them as the boost went up. When I got to a 3.5 pulley ratio the EGTs scared me and the heat from it melted the SC belt. I believe I saw upwards of 1225C on a 3.5PR. I've seen 1050c to 1100c peaks on all 10 audis i've owned during the past 14 years.

Mike

Thanks, Mike. On turbo cars (where I have more experience) very high EGTs affect turbo life, as the heat can soften the center shaft, and destroy bearings. On one platform we had to stay below 1600 F. (also calculated) to protect the turbo. We didn't care about cats as most of us were running catless and cats were easy to access and remove.

Are your values taken via VCDS?

[bhvrdr]

Thanks, Mike. On turbo cars (where I have more experience) very high EGTs affect turbo life, as the heat can soften the center shaft, and destroy bearings. On one platform we had to stay below 1600 F. (also calculated) to protect the turbo. We didn't care about cats as most of us were running catless and cats were easy to access and remove.

Are your values taken via VCDS?

yeah all vcds.

I've had turbo cars and NA from audi. At least on the B6 A4, B7 A4, B8 A4 boards we never had issues with people killing turbos and any EGT related issues I can think of other than cats like you say. I remember peaking 29psi on the B6.

Bosch would spec peak temps in the 1050c range was as high as they liked to see in their manuals IIRC.

Even back then in 2003 audi was running enrichment strategies on the MED so seeing .78 lambda up top on WOT runs wasnt unusual.

Seems like people were bending rods or head gaskets more in the B6 days and of course on the B8 A4 those engines tear themselves apart from looking at them funny on stock tunes.

Mike

[Dippy]

It may not be relevant, but I found out that in my ECU there are 2 pairs of EGT values. I have IDE00167/8 "Exhaust temperature 1 bank 1/2" and IDE02116/08263 "Exhaust gas temperature before catalytic converter/Exhaust gas temperature before catalytic converter: bank 2". I have seen the former go just over 1000C, and the latter peaks at somewhere between 850C and 900C. As we know these values are calculated, it might be important to know for any particular ECU, at what point along the exhaust the calculation is supposed to represent.