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Question for 991.2 owners that have installed the Cobb tune

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Question for 991.2 owners that have installed the Cobb tune

 
Old 06-02-2019, 08:00 PM
  #16  
Norge911
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Also need to add high flow filter, car needs more air as well. Those poor little things are sucking like crazy and are getting all winded.

Question, from what I have read, with stage 2 type or custom tunes, isn’t it recommended to go cat less?
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Old 06-02-2019, 09:01 PM
  #17  
arter
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plot of your run ( datalog 7 )shows opening of throttle blade and wastegate occurs at 6000 rpm.
Throttle blade changes angle even if you have your foot planted based on ECU.
Calculated engine torque was running at ECU limit ( might be why throttle blade opened up).
RPM is blue ( divided by 100), yellow is net boost in psi, grey is wastegate, brown is actual throttle blade angle.


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Old 06-02-2019, 10:53 PM
  #18  
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I have restore the stage 0 map and here's the datalog

Thanks everyone for their inputs
Attached Files
File Type: csv
datalog12.csv (80.9 KB, 19 views)
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Old 06-02-2019, 10:57 PM
  #19  
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Originally Posted by arter View Post
plot of your run ( datalog 7 )shows opening of throttle blade and wastegate occurs at 6000 rpm.
Throttle blade changes angle even if you have your foot planted based on ECU.
Calculated engine torque was running at ECU limit ( might be why throttle blade opened up).
RPM is blue ( divided by 100), yellow is net boost in psi, grey is wastegate, brown is actual throttle blade angle.


1. You guys are awesome for doing these plots
2. Thats the craziest plot ive ever seen
3. This is gonna be interesting
4. OP. I hope its just the software
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Old 06-03-2019, 01:03 AM
  #20  
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Originally Posted by 991.2GTS View Post
I have restore the stage 0 map and here's the datalog

Thanks everyone for their inputs
Stage 0 has similar timing pull to performance tune. Looks like fuel may be the culprit.
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Old 06-03-2019, 01:10 AM
  #21  
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Stock map shows same effect on boost, throttle blade, with your setup at 6000 rpm
red line if ECU max torque allowed, green calc torque
throttle blade opens if calc torque rises above max torque
note with tune you were getting boost of 25psi, torque of 540 ft-lb
stock map boost of 16 psi, torque more like 420
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Old 06-03-2019, 01:12 AM
  #22  
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I don't feel the boost drop at stage 0, but maybe because the boost wasn't as crazy before 6000rpm thats why it feels smooth. So you guys think is the fuel problem right?
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Old 06-03-2019, 01:17 AM
  #23  
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timing is connected to fuel, intake temp, and ECU other senses..... so higher octane would help. ( colder days..... etc etc.)
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Old 06-03-2019, 02:09 AM
  #24  
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Originally Posted by 991.2GTS View Post
I have restore the stage 0 map and here's the datalog

Thanks everyone for their inputs
Still pulling tons of timing. Try different fuel. And drive easy until this tank is gone.
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Old 06-03-2019, 04:55 PM
  #25  
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So I got a reply from Cobb and they basically saying maybe cause I have a header that's why everything is off.
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Old 06-03-2019, 05:18 PM
  #26  
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Originally Posted by 991.2GTS View Post
So I got a reply from Cobb and they basically saying maybe cause I have a header that's why everything is off.
No, the headers won't cause that much of a change. That plot I showed from another car is WITH a header. I honestly believe it's a bad tank of gas. Or, slightly possible, you have some loose nuts or something that are vibrating and causing false knock.

edit: it's not unheard of for the premium tank at the station to have been filled with regular (accidentally or not...). I bet you just got a tank of low octane fuel.

Last edited by spdracerut; 06-03-2019 at 06:14 PM.
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Old 06-03-2019, 05:26 PM
  #27  
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What about intercoolers, did you upgrade? if not, this is your next step along with airfilter, plenum and maybe consider removing cats.

When tuning turbo charged engines, need to increase air mass and improve airflow. First and easy gains are;
1. Air filter
2. Intercoolers
3. Cats.
For stage 2 type tune and incremental change in airflow;
1. Plenum (and intercooler if not already completed)
2. Headers/down pipes
3. remove cats, replace muffler
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Old 06-03-2019, 09:45 PM
  #28  
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I will definitely try another gas station and keep the stage 0 map for now and do another datalog.
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Old 06-04-2019, 12:41 AM
  #29  
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For what it's worth, my car was used to develop the stage 2 map. I have akra cats and exhaust and no other mods, so that's what the OTS stage 2 map was developed with/for. With my setup, I have none of these issues. It pulls strong all the way, and there is no clunkiness or other drivability issues.

Just wanted to clarify for the people saying you need this or that for the Cobb stage 2 map. You only need high flow cats and nothing else.
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Old 06-04-2019, 01:03 AM
  #30  
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