996 Turbo / GT2 Turbo discussion on previous model 2000-2005 Porsche 911 Twin Turbo and 911 GT2.

What are normal values for post cat O2 sensors on this car?

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Old 12-07-2013, 02:01 PM
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What are normal values for post cat O2 sensors on this car?

Ever since I unplugged the battery a few months ago I have had a hell of a time getting all my monitors to switch to ready so I can pass inspection. I got a Durametric a month or so ago so I could monitor what was going on and found a code chilling in the background that didn't actually trip the CEL. I have since fixed that, disconnected the battery again, and am working on getting those monitors set.

The monitors I am having trouble with are for the cats and HO2 sensors. I have attempted the drive cycles to reset the monitors. I have logged pre and post cat O2 sensor values. Rear O2's are generally 0.00v-0.08 v at idle and 0.65v - 0.80v cruising. Idle seems fine to me, but is the cruising a little high?

In reviewing the logs I notice that one bank seems to lag compared to the other when going from on throttle to off throttle. Is this normal? I have no codes for slow response on O2 sensors.

Other relevant information:

Last time I know for sure I had all monitors ready (last inspection) I had the same EPL tune, modded stock exhaust (pretty sure it is stock cats), old O2 sensors.

Now I have the same EPL tune, AP exhaust with 200 cell cats, and fresh front O2 sensors.

I spoke with someone at EPL. They stated my tune does not turn off any monitors.

I know cat monitors tend to take a while to set but I am starting to get antsy now that I am two months late on inspection.
 
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Old 12-07-2013, 03:42 PM
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Originally Posted by sinKing
Ever since I unplugged the battery a few months ago I have had a hell of a time getting all my monitors to switch to ready so I can pass inspection. I got a Durametric a month or so ago so I could monitor what was going on and found a code chilling in the background that didn't actually trip the CEL. I have since fixed that, disconnected the battery again, and am working on getting those monitors set.

The monitors I am having trouble with are for the cats and HO2 sensors. I have attempted the drive cycles to reset the monitors. I have logged pre and post cat O2 sensor values. Rear O2's are generally 0.00v-0.08 v at idle and 0.65v - 0.80v cruising. Idle seems fine to me, but is the cruising a little high?

In reviewing the logs I notice that one bank seems to lag compared to the other when going from on throttle to off throttle. Is this normal? I have no codes for slow response on O2 sensors.

Other relevant information:

Last time I know for sure I had all monitors ready (last inspection) I had the same EPL tune, modded stock exhaust (pretty sure it is stock cats), old O2 sensors.

Now I have the same EPL tune, AP exhaust with 200 cell cats, and fresh front O2 sensors.

I spoke with someone at EPL. They stated my tune does not turn off any monitors.

I know cat monitors tend to take a while to set but I am starting to get antsy now that I am two months late on inspection.

One thing i learned if its not broke don't touch it lol the volts that your seeing are about the same as mine cruising.
 
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Old 12-07-2013, 04:30 PM
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Originally Posted by 996tt550hp
One thing i learned if its not broke don't touch it lol the volts that your seeing are about the same as mine cruising.
It's not really about that. It is about whether the high flow cats I have are efficient enough for my car. I don't want to waste my time waiting for my monitors to switch to ready when I could just put my stock system back on for inspection. However, I don't want to waste my time putting my stock system back on if everything here is withing normal range.
 
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Old 12-07-2013, 10:20 PM
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Been a while since I viewed the #2 sensor voltages with my Turbo. Generally the post cat sensors want to read 0.65 or better, which indicates low oxygen content in the exhaust gas. The oxygen is being consumed in the converters as they process exhaust gases. The ECU knows there should be excess oxygen for this as it monitors the #1 sensors to see an excess of oxygen going into the converters.

A 0.0V reading at the #2 sensors is not a good sign. My Boxster's #2 sensor (one bank) reads low -- say down to 0.2V -- when I check it after the CEL comes on and the I read a DTC of P0430: converter operating below efficiency.

If the sensors are reading that low the readiness monitors for the converters will likely not be set to complete and if you drove the car enough -- roughly 30 miles of mixed driving -- you'd probably get a CEL.
 
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Old 12-08-2013, 03:58 AM
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over 50000miles and tuning (more heat vs. stock) the monitorsonde are old and slow...and the sensoring isnt good
 
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Old 12-21-2013, 04:29 PM
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Update: EPL sent me an updated tune that helped set the monitors. I successfully passed inspection today.

I couple months ago I had gotten frustrated with the communication with EPL when shopping for my next tune but they really redeemed themselves with this interaction. Maybe they were just very busy back then and only quickly glancing over my emails but Dave @ EPL was very responsive and thorough in his emails this time around. They stood behind their product even though I was not the original purchaser.
 
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