Question for 991.2 owners that have installed the Cobb tune
 

Last week i installed the Cobb tune stage 2 on 2018 GTS. My car has ak exhaust, fabspeed 200 cel and header. Question is do you guys that have the Cobb tune feel like the pull less after 6000rpm, cause this is what happened to my car. I feel my car has a boost drop after 6000rpm, especially 3rd and 4th gear, I know the gauge in the car is not as accurate but it dropped to 12psi after 6000rpm. Anyone experience the same problem? Thanks guys

i did change to stage 1 map and it seems the boost drop not as much but probably because the stage 1 pull less before 6000rpm

connect up your cobb unit in datalogger mode and see what is happening during a pull

Doesn't sound right. Possibly the boost tables messed up due to your specific exhaust mods not working well with the OTS map. Happens periodically to my friend with cobb on his base after exhaust install.

I loved the power from the tune, but the drive became clunky.... did a transmission reset and the drive quality improved significantly, can give that a shot

With those mods you will need a pro tune
You can confirm that by just calling cobb

Yeah... the Stage 2 tune was done on a car with only high flow cats, IIRC. So with the headers and exhaust, you freed up some more flow. I bet you're getting a lot of knock and the ecu is pulling ignition timing in the upper rpm range. However, with a COBB tune, it should be doing like ~21psi of boost at redline. So if it's dropping all the way to 12psi, there's some serious stuff going on where the engine isn't happy about something and trying to save itself by lowering boost/power. Or you have a massive boost leak. I'm assuming you have premium gas in it? I suppose it's possible you got a bad tank of gas. If you datalog it to see what the car is doing, it may help the diagnosis.

That's the thing - once you start messing with stock, getting stability and reliability takes some effort.

You didn't mention any improvements on the intake side, like BMC and plenum mods. They say Stage 1 requires BMC or equal. For Stage 2 I'd want the BMC and plenum mods. I'd try those first, b4 spending more on another custom tune.

I do have plenum but stock intake filter. After I change it back to stage 0 map everything is fine so I hope is not any boost leak. I will upload a Datalog a bit later and see if you guys can see the problem

Im using the 91 map because the 94 gas that I’m using here in Canada got like 0 ethanol

I recall reading some GTS turbos dropping off PSI at higher RPMs due to poor lubrication and replacements was fix. It was a really obvious drop though...its normal for all 991.2 turbos to drop 2-3 PSI near redline.

Assuming its less than ideal conditions like hot outside or high altitude, GTS will boost 15/16 PSI in mid RPMs then near redline or past 6k you could see 12/13....so I would consider it normal for stock. Doubt you should go to dealer since its not stock. Your best bet is to call Cobb...they'll probably be more helpful. My 2 cents is that its normal and your guage is not functioning correctly due to tune (its probably boosting to 16 when it says 13 in the meter). Its possible Cobb tune made mid RPMs stronger and than higher RPMs so its a perception thing.

You can and should use the 93 file.

COBB recommends data logging the car with the AP to verify there is no timing pull. If there is timing pull, then switch to the 91 file.

The datalog7 and datalog10 one are from stage 2 map and the datalog11 one from the stage 1 map. Any expert here know how to analyze this? The ignition timing seems a bit off compare to other members' datalog

Btw, thank you for everyone's input, you guys have been helpful

If its 94 RON then he needs the 91 octane map. 98 RON is for the 93 map

Your car is pulling insane amounts of timing.

This is what a so-so timing map looks like. It's still pulling some timing at ~4200rpm as you can see by the step down/retard of the timing. But it's running about 9-10 degrees of timing above 6k rpm.
https://cimg8.ibsrv.net/gimg/rennlis...8c1ed2db2c.jpg

This is what your car is doing. It's running like -6 degrees. And you can see the drop in boost at ~5800rpm as the engine is trying to save itself.
https://cimg4.ibsrv.net/gimg/rennlis...b02552b0ff.jpg

Looking at the data, I highlighted the columns which show timing correction for each cylinder. You're getting massive timing retard for each cylinder which also causes the main ignition timing to drop.
https://cimg2.ibsrv.net/gimg/rennlis...3fa35ec2b3.jpg


I would try different gas. A different station and just the highest octane there is. This beyond a tune vs. parts issues. This is just bad gas in my opinion.

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?

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.


https://cimg1.ibsrv.net/gimg/rennlis...caf77b3a43.jpg

I have restore the stage 0 map and here's the datalog

Thanks everyone for their inputs

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

Stage 0 has similar timing pull to performance tune. Looks like fuel may be the culprit.

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
https://cimg2.ibsrv.net/gimg/rennlis...288fb249a3.jpg

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?

timing is connected to fuel, intake temp, and ECU other senses..... so higher octane would help. ( colder days..... etc etc.)

Still pulling tons of timing. Try different fuel. And drive easy until this tank is gone.

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.

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

I will definitely try another gas station and keep the stage 0 map for now and do another datalog.

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.

https://cimg4.ibsrv.net/gimg/rennlis...1b8d91fbfb.png

So I have put in new fuel and seems the same. I have looked at the datalog again and I saw that over 6100rpm the torque reduction request is on. Is what circumstance the torque reduction request will trigger?

Thanks

I would go to a Cobb pro tune.

The torque limit allowed is much higher for a stage 1 tune than stock.
Your stage 2 tune torque limit should be slightly higher than a stage 2 tune ( I have not checked this).
A pro tune could possibly increase this further.

Bad gas would effect timing and reduce power which would decrease your torque actual and prevent you from hitting the torque limit ( yea???) by slowing you down.

Are you seeing the timing retard and boost reduction? Also, different gas station?

What did cobb say about the logs? Just curious, although i doubt insight will go beyond the comprehensive analyses above. If this was my car, I would have a shop check the turbos and for exhaust/manifold leaks and if hardware is ok do a protune. I have been told if the engine was knocking alot it will throw a CEL. There also appears to be a need for a TCU tune. Is it possible some of this is TCU intervention?

Since working fine at stage 0 I still think it is being choked. Need better air filter, and upgraded intercoolers.

I'll log my car on stage 1 and stage 0 tonight and report results.

I will upload my datalog again tomorrow. Today I went to track with the stage 2 map. After couple sessions (3rd gear after 6000rpm still struggle), my ecu seemed like reset the stage 2 and back to stage 0 (the boost gauge not getting over 15-17 psi) and the power was linear like stock. After I cool down my car after couple hours and it was the same, the power is exactly like stock (linear with boost arond 14-15 psi). I think I may just uninstall it and sell it.

Based on your previous datalogs, if it isn't a gas quality issue, you have some mechanical issue. All the ecu is doing is detecting tons of knock and retarding the timing and boost to save the engine. The question is, why is it detecting tons of knock?

So this is my datalog from last night. Pretty obvious is in some kind of limp mode or stock map.

It looks like stock map boost levels. It's still pulling tons of timing because it's detecting a ton of knock. As it seems you eliminated fuel quality as the issue, it leads me to believe there's some issue with the install of your exhaust components which is leading to the detected knock.

https://cimg1.ibsrv.net/gimg/rennlis...dd534596df.jpg

Did you end up doing the datalog?

Rain prevented it. I'll need to try again this weekend.

So this is the error code I got. Maybe is related? I see some post from before that the Cobb tune leads to some pdk error codehttps://cimg0.ibsrv.net/gimg/rennlis...7042a6588.jpeg

No, unrelated to all the knock you're getting. Unless there's something inside the transmission rattling around like a can full of nuts and bolts.

To continue to beat a dead horse, if you go on track with stage 2 and you haven’t changed air filter and you intercoolers you get way too hot air into your engine.
I would make these changes before scrapping the COBB.



“I ride my horse and whip my porsche”

I know I’m new to this forum, and I have a 718 Base, but I have Cobb stage 1 and have the same codes as you. PDK and UC401. Trying to figure out what is causing it.

I got a question two for those with chrono pack
does the tune stage 1 or 2 retain the default characteristics of sports and sports plus mode?
in sports there is backfire
in sports plus no backfire but constant boost of 1psi at idle and always on boost

My friend has cobb and after a recent update the sport and sport+ burbles got mixed up. None in sport and burbling in sport +. Not sure if other folks have this experience as well. Everything else works as stock afaik.

I plan on using access port just for upload/download of custom maps, still have 600miles to go before breakin
plan on tweaking just the sport and sports+ maps for a bit more power, all custom. nothing aggressive. Dyno/road tune to make sure its a daily driver.
I am Apex Autoworks lined up in NJ

Just curious if there is any data/logs to back this up? I have been running stage 2 as well as doing pulls and logs with John at BGB for a protune and have noticed no issues with the stock air filter and stock intercoolers (my only mod is cat bypass pipes). The intake air temps are actually really close to ambient temps (or even below depending if the wing is up or not) and it seems to have no impact on knock or timing pulls. I do agree that the air filter and intercooler cannot hurt-just not sure how necessary they are off the bat.

did you ever figure it out @axthomson ? or anyone else getting this code?

mine shows the same codes, seems to run fine though

Y'all ever sort out the UC401?