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  1. #1
    Senior Member Three Rings quietcropduster's Avatar
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    Are my CAT temps too high?

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    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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  2. #2
    Established Member Two Rings
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    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.

  3. #3
    Established Member Two Rings PenttisHSR's Avatar
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    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

  4. #4
    Established Member Three Rings MSq5's Avatar
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    Quote Originally Posted by PenttisHSR View Post
    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.
    Last edited by MSq5; 08-12-2018 at 03:12 PM.
    2017 Q5 3.0T S-Line | Brilliant Black | EPL Stage 2 93 octane tune | JHM 179mm crank pulley | aFe Pro 5R (part#10-10121) filter in "modified" stock air box | 034 silicone throttle body hose | HP Tuners custom TCU tuned ZF8

  5. #5
    Established Member Two Rings PenttisHSR's Avatar
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    Problem is that those of us who came from the B5 S4 had 2 actual EGT sensors.

  6. #6
    Veteran Member Four Rings fitzydude's Avatar
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    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
    2010 S4 / 6MT / 034 RSWB & Motor Mounts / AMS Cooling / EC Alu Kreuz & inserts / B12 suspension / CTS SC & JHM OD Pulley (PR:3.139) / JHM STS & Stg 4 clutch / Magnaflow w/cutouts / CTS Downpipes / V710 / Eventuri-Euro / USP clutch line / E35 / Chipwerke 3-1 / Revo - 467 awhp

  7. #7
    Active Member Two Rings
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    Shit, I'm hitting 1100C per side on DP. That's 2012F.

  8. #8
    Senior Member Three Rings quietcropduster's Avatar
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    Quote Originally Posted by SCHOUGY View Post
    Shit, I'm hitting 1100C per side on DP. That's 2012F.
    Damn that's high lol

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  9. #9
    Established Member Three Rings MSq5's Avatar
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    Quote Originally Posted by PenttisHSR View Post
    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.
    Last edited by MSq5; 08-14-2018 at 07:16 AM.
    2017 Q5 3.0T S-Line | Brilliant Black | EPL Stage 2 93 octane tune | JHM 179mm crank pulley | aFe Pro 5R (part#10-10121) filter in "modified" stock air box | 034 silicone throttle body hose | HP Tuners custom TCU tuned ZF8

  10. #10
    Veteran Member Four Rings bhvrdr's Avatar
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    Quote Originally Posted by MSq5 View Post
    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

    2010 Audi A4 Avant 6AT - Unitronic Tuned - Bone Stock Hardware
    13.665 at 97.71mph - 93 octane - +1250DA
    Gone:
    2013 Audi S5 DSG - Unitronic Stage 2++ ECU & TCU, 3.17pr, Revo Charge Cooler, CTS Turbo Intake, ST60 380mm BBK
    11.482 at 118.70mph - 97 octane - +465DA
    --------------------------
    2016 A6 -- 2015 S4 -- 2009 A4 -- 2004 S4 -- 2006 A4 -- 2003 A4 -- 2000 A4

  11. #11
    Established Member Three Rings MSq5's Avatar
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    Quote Originally Posted by bhvrdr View Post
    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?
    2017 Q5 3.0T S-Line | Brilliant Black | EPL Stage 2 93 octane tune | JHM 179mm crank pulley | aFe Pro 5R (part#10-10121) filter in "modified" stock air box | 034 silicone throttle body hose | HP Tuners custom TCU tuned ZF8

  12. #12
    Veteran Member Four Rings bhvrdr's Avatar
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    Quote Originally Posted by MSq5 View Post
    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

    2010 Audi A4 Avant 6AT - Unitronic Tuned - Bone Stock Hardware
    13.665 at 97.71mph - 93 octane - +1250DA
    Gone:
    2013 Audi S5 DSG - Unitronic Stage 2++ ECU & TCU, 3.17pr, Revo Charge Cooler, CTS Turbo Intake, ST60 380mm BBK
    11.482 at 118.70mph - 97 octane - +465DA
    --------------------------
    2016 A6 -- 2015 S4 -- 2009 A4 -- 2004 S4 -- 2006 A4 -- 2003 A4 -- 2000 A4

  13. #13
    Senior Member Two Rings
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    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.
    2015 monsoon grey S5 sportback (yes the one with 4 doors)
    - MRC stage 2 (189mm Vdamper/Fluidampr crank pulley)



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