991.2 Cobb Tune Issue
#16
Drifting
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Wish there was a way to "open up" the factory gauge to read more (say up to 30 PSI). Not that we go that high but its nice to have a taller ceiling. My workaround since my car only goes to 15 psi (carerra T) is to have the accessport mounted and in monitor mode. For the future, I may put a boost gauge where the factory sport chrono clock goes..but I like the clean look without it.
#17
Rennlist Member
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Wish there was a way to "open up" the factory gauge to read more (say up to 30 PSI). Not that we go that high but its nice to have a taller ceiling. My workaround since my car only goes to 15 psi (carerra T) is to have the accessport mounted and in monitor mode. For the future, I may put a boost gauge where the factory sport chrono clock goes..but I like the clean look without it.
Did a lot of neat stuff with Bimmers with it.
#18
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Looked at the data log in the accessport and found that pre-boost (actual) seems to be the actual reported boost + ATM. So at sea level basically 14.8 or so PSI would have to be subtracted from the total pre-boost to get the real turbo compression. I am learning here so these are assumptions not fact.
In my case, I am at roughly 6500ft when I ran the 3rd gear pull. It shows a resting (actual) pre-boost @800 RPM idle of 11.8 PSI and a maximum (actual) pre-boost of 29.2 @ 4300 RPM wide open throttle. Thus a net of 17.4PSI actual boost - which coincidentally is exactly what my gauge shows.
I know many on here subscribe to the notion that the gauge is limited somehow but other threads are showing boost readings up to 18PSI at least where the GTS is supposed to be from factory. Ergo, I would expect to see at least 18 if that were the limiting factor assuming the S and GTS don't have different gauges. If data log showed more net boost I'd pack it up and agree that its a gauge issue. Not buying it now.
Other theory is that denser air (I ran this pull at 56 deg F) will be limited by the absolute torque maximum not max boost. Which makes a ton of sense. Over boost can blow up motors - but the max PSI values in the data I pulled show a consistent lower PSI than target or max values. I did see a -3.8 degree timing correction but I'm pretty far out of my depth at this point and have no idea what the heirarchy here is and how it would impact max boost. I saw zero torque limitation in the values so not sure on this one either.
All data now pointing to some deficiency in fuel or programming but hey, I'm obviously no ECU programmer. Best shot is for Cobb to diagnose.
In my case, I am at roughly 6500ft when I ran the 3rd gear pull. It shows a resting (actual) pre-boost @800 RPM idle of 11.8 PSI and a maximum (actual) pre-boost of 29.2 @ 4300 RPM wide open throttle. Thus a net of 17.4PSI actual boost - which coincidentally is exactly what my gauge shows.
I know many on here subscribe to the notion that the gauge is limited somehow but other threads are showing boost readings up to 18PSI at least where the GTS is supposed to be from factory. Ergo, I would expect to see at least 18 if that were the limiting factor assuming the S and GTS don't have different gauges. If data log showed more net boost I'd pack it up and agree that its a gauge issue. Not buying it now.
Other theory is that denser air (I ran this pull at 56 deg F) will be limited by the absolute torque maximum not max boost. Which makes a ton of sense. Over boost can blow up motors - but the max PSI values in the data I pulled show a consistent lower PSI than target or max values. I did see a -3.8 degree timing correction but I'm pretty far out of my depth at this point and have no idea what the heirarchy here is and how it would impact max boost. I saw zero torque limitation in the values so not sure on this one either.
All data now pointing to some deficiency in fuel or programming but hey, I'm obviously no ECU programmer. Best shot is for Cobb to diagnose.
#19
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on my GTS I would get boost pressures up to 28 psi ( v1.02) using boost minus 14.7 and the guage never went above 19 psi ( max stock for GTS).
V1.06 doesnt go as high anymore, but still like 23-24 psi.
yeah you have to use the datalogger to see what is happening. send to log to cobb and ask them about it.
V1.06 doesnt go as high anymore, but still like 23-24 psi.
yeah you have to use the datalogger to see what is happening. send to log to cobb and ask them about it.
#23
Rennlist Member
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Looked at the data log in the accessport and found that pre-boost (actual) seems to be the actual reported boost + ATM. So at sea level basically 14.8 or so PSI would have to be subtracted from the total pre-boost to get the real turbo compression. I am learning here so these are assumptions not fact.
In my case, I am at roughly 6500ft when I ran the 3rd gear pull. It shows a resting (actual) pre-boost @800 RPM idle of 11.8 PSI and a maximum (actual) pre-boost of 29.2 @ 4300 RPM wide open throttle. Thus a net of 17.4PSI actual boost - which coincidentally is exactly what my gauge shows.
I know many on here subscribe to the notion that the gauge is limited somehow but other threads are showing boost readings up to 18PSI at least where the GTS is supposed to be from factory. Ergo, I would expect to see at least 18 if that were the limiting factor assuming the S and GTS don't have different gauges. If data log showed more net boost I'd pack it up and agree that its a gauge issue. Not buying it now.
Other theory is that denser air (I ran this pull at 56 deg F) will be limited by the absolute torque maximum not max boost. Which makes a ton of sense. Over boost can blow up motors - but the max PSI values in the data I pulled show a consistent lower PSI than target or max values. I did see a -3.8 degree timing correction but I'm pretty far out of my depth at this point and have no idea what the heirarchy here is and how it would impact max boost. I saw zero torque limitation in the values so not sure on this one either.
All data now pointing to some deficiency in fuel or programming but hey, I'm obviously no ECU programmer. Best shot is for Cobb to diagnose.
In my case, I am at roughly 6500ft when I ran the 3rd gear pull. It shows a resting (actual) pre-boost @800 RPM idle of 11.8 PSI and a maximum (actual) pre-boost of 29.2 @ 4300 RPM wide open throttle. Thus a net of 17.4PSI actual boost - which coincidentally is exactly what my gauge shows.
I know many on here subscribe to the notion that the gauge is limited somehow but other threads are showing boost readings up to 18PSI at least where the GTS is supposed to be from factory. Ergo, I would expect to see at least 18 if that were the limiting factor assuming the S and GTS don't have different gauges. If data log showed more net boost I'd pack it up and agree that its a gauge issue. Not buying it now.
Other theory is that denser air (I ran this pull at 56 deg F) will be limited by the absolute torque maximum not max boost. Which makes a ton of sense. Over boost can blow up motors - but the max PSI values in the data I pulled show a consistent lower PSI than target or max values. I did see a -3.8 degree timing correction but I'm pretty far out of my depth at this point and have no idea what the heirarchy here is and how it would impact max boost. I saw zero torque limitation in the values so not sure on this one either.
All data now pointing to some deficiency in fuel or programming but hey, I'm obviously no ECU programmer. Best shot is for Cobb to diagnose.
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Carlo_Carrera (04-22-2020)
#24
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Well I guess I have this desire to see data and there's some above in my post that conflicts with some of the non data based statements. If you actually read and understood what wrote you might agree that there's a ton conflicting opinions on this and related threads. I spend hours today sifting through them and still no factual evidence that the gauge is limited by model. Base / S / GTS using the same basic hardware somehow individually limited. The point of this is to get to the bottom of it and ask the right questions.
I hope you're right about the PSI gauge but you've brought no facts or data to the discussion but feel it necessary to be combative and critical without offering anything.
I hope you're right about the PSI gauge but you've brought no facts or data to the discussion but feel it necessary to be combative and critical without offering anything.
#25
Rennlist Member
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Well I guess I have this desire to see data and there's some above in my post that conflicts with some of the non data based statements. If you actually read and understood what wrote you might agree that there's a ton conflicting opinions on this and related threads. I spend hours today sifting through them and still no factual evidence that the gauge is limited by model. Base / S / GTS using the same basic hardware somehow individually limited. The point of this is to get to the bottom of it and ask the right questions.
I hope you're right about the PSI gauge but you've brought no facts or data to the discussion but feel it necessary to be combative and critical without offering anything.
I hope you're right about the PSI gauge but you've brought no facts or data to the discussion but feel it necessary to be combative and critical without offering anything.
Regardless, if you ever find anything that says the factory gauge will go over 17 psi in the base/s models, please do enlighten us. I would definitely be intrigued by that!
#26
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Actually that's where youre wrong. I didn't ask for an opinion I asked for facts. And I didn't toss aside the genuine help that was offered, I'm simply offering data in response to an ongoing discussion that didn't land on a definitive conclusion. Damn I don't get why you trolls get so much enjoyment out of creating conflict on forums.
#27
Rennlist Member
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Actually that's where youre wrong. I didn't ask for an opinion I asked for facts. And I didn't toss aside the genuine help that was offered, I'm simply offering data in response to an ongoing discussion that didn't land on a definitive conclusion. Damn I don't get why you trolls get so much enjoyment out of creating conflict on forums.
If you want, I can see if one or two of the techs can put something in writing and post it up here if that helps with the facts part. I've tried to find literature on it previously, but was unable to. Again, I'll be following along because I would love to hear if someone finds information out there that goes against what everyone has known (or assumed to know) for the past couple of years.
#28
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You are not even a member and you are basically telling us that you are too good to search? And I am a troll? Read some of my posts and you will see how much I contribute to this forum, while you get defensive after a few posts?! The next time you have a question you better search because with that attitude you will be lucky to get an answer otherwise.
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Baba Ghanoush (04-23-2020)
#29
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From the Cobb maps notes page.
https://cobbtuning.atlassian.net/wik...rera+Map+Notes
Boost Target:
https://cobbtuning.atlassian.net/wik...rera+Map+Notes
Boost Target:
- 91 Octane (95 RON Minimum): 18 psi +/- 2psi tapering off to redline
- 93 Octane (98 RON Minimum): 18 psi +/- 2psi tapering off to redline
#30
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Post a log. Happy to review and let you know if there are any issues.
If there is a boost leak or any major issue, it should be easy to spot.
If there is a boost leak or any major issue, it should be easy to spot.