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Discussion Starter · #1 ·
Hello all,

just recently purchased a 2015 GT-R. I purchased the Cobb Big SF intake system and installed it this weekend. I installed the accessport with the stage 1 Big SF tune. Everything went well until I started the engine. There was harsh shuddering and low revving. CEL appeared along with other dash lights. After a short time I turned the engine off and checked the codes with the accessport.

TRANS
P2637
P2641
E-SUS
C1D04

I reset the ECU and tried again. Same shuddering and codes.
I tried uninstalling the accessport and same thing occurred.
I tried uninstalling and reinstalling the MAF senors on the intakes and same result. Each time I reset the ECU.

I even tried disconnecting the battery and the same thing would still happen.
Do you think there is an air leak somewhere? When you do this install you have to remove the charge pipe and blow off valve piping...maybe this is the issue? Everything looks good visually. I haven't taken everything apart yet to check connections.
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Anyone go through this? I have an email out to Cobb but being its a Sunday they won't get back to me until tomorrow or the following day.
Let me know your thoughts. Thanks
 

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Moved to the COBB sub-forum
 

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Discussion Starter · #4 ·
Are you sure you are loading the correct map? I believe it's actually Stage 1+, the other is for stock size intake. Double check that and let us know.
Yes. Stage 1+ Big SF. I have gone over and over all the connections. In and out with the MAF sensors. Next step is to take it all apart again to recheck connections/hoses and try again. If that doesn’t work then I’ll likely reinstall factory intake and uninstall the accessport. I’m also still waiting to hear from Cobb. So frustrating
 

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You can also try a stage 2 map just as a test, idle/no load won't matter. If it still doesn't work then definitely something else is going on.
 

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MAJJ
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the harsh shuddering happened to me as well when I first got the Cobb big intake, but no codes. turned out being the clamps and the silicone hose not being tight enough -- leak.
 

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Discussion Starter · #7 ·
After talking with Cobb I uninstalled and then reinstalled the accessport with the stage 1+ tune. No change. I have a video and the data log. I'll wait to hear from Cobb again but I'll try uninstalling the entire intake and reinstalling it again to check all the hoses/clamps etc once again.

 

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You've got a significant flow difference across banks as you can see from the MAF voltages. Please include in the next log "ECU Throttle Pos. B2" so I can see if they are trimming the same. Before we get into logging ISC parameters, with the car off unplug each throttle body connector and then reconnect the plug to make sure they are seated properly. Next, swap MAF sensors to the other side and redo the same log. I suspect your issue is something trivial, but we'll see if we can get it sorted.

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Discussion Starter · #9 ·
Thanks for the info. I appreciate it. I also Noticed something was off with the airflow from B1 to B2. Is there a way to determine which side this is, left or right ? Would this possibly indicate a leak in the intake somewhere throwing off the air inflow readings ? I was planning on removing the intake completely tomorrow as well as the charge pipe/blow off valve set up to look for a loose fitting and then put it all back together. Could it even be at the cone filter? Those were a pain in the ass to get in there. Is there a way to determine right or left MAF sensors ? I looked at them closely and the only different numbers or letters I could see was one has an “L” and one has a “K”. To the rest of your recommendations…..I’m an amateur at this stuff. I don’t know how to decided what parameters I am logging. It’s on an accessport from Cobb. I’ll try the throttle body trick and can try switching the MAF sensors again…. Thanks !
 

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Bank 1 = Passenger Side
Bank 2 = Driver Side

MAF sensors are the same so just swap them to see if the flow issue follows the MAF or if it stays with the Bank. You'll need to select the logging parameters in your AP. Unplug the throttle body connectors and then reconnect them just to make sure there is no issue. Repeat the log.
 

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Although it is a remote possibility, check that the MAF sensor housing wasn't welded/molded backwards in the intake pipe. That type of manufacturing error has happened in the past.
 

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Discussion Starter · #12 ·
Good point. I swear the sensor wiring harness is turned the opposite direction when plugged in into the carbon intake compared to the stock intake. I’ll check it out
 

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Discussion Starter · #13 ·
L.L. I believe you are correct. I got the stock intakes back out and checked the OEM orientation of the MAF sensor housing. I confirmed that the lettering of the MAF sensors should be facing forward towards the filter on both sides. I then went back to the Cobb intake and realized that on the passenger side the only orientation that will fit is with the sensor letters towards the engine (opposite of OEM). I wonder if this could be the culprit. I'll reach out to Cobb and see what they say. Good thinking!

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Can you zoom out on the passenger side tube?
 

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Discussion Starter · #15 ·
L.L. I believe you are correct. I got the stock intakes back out and checked the OEM orientation of the MAF sensor housing. I confirmed that the lettering of the MAF sensors should be facing forward towards the filter on both sides. I then went back to the Cobb intake and realized that on the passenger side the only orientation that will fit is with the sensor letters towards the engine (opposite of OEM). I wonder if this could be the culprit. I'll reach out to Cobb and see what they say. Good thinking!

View attachment 401441 View attachment 401442 View attachment 401443 View attachment 401444
 

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Discussion Starter · #16 ·
Two more pics....one with the MAF bolted in place (wrong direction) and one with the correct orientation without the bolts. Both pics on passenger side.
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L.L. FTW

who’d a thunk that was the issue?
 

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Discussion Starter · #18 ·
After multiple emails and pictures back and forth with Cobb, they confirmed that the passenger intake MAF sensor housing was manfufactured or put together backwords forcing the sensor to be placed in the opposite direction from OEM. They are over-nighting a new passenger intake. I'll install it this weekend and hope this solves my issues. I'll let you guys know. Thanks again to L.L and 240Z Twin Turbo. Much appreciated.
 

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Discussion Starter · #19 ·
UPDATE:
Removed the passenger side intake with the faulty MAF sensor position and installed the new one that was over-nighted by Cobb. Attached is the data log after install. Engine ran fine. No CEL. The MAF readings on the data log are about 4-7 hundredths off from side to side (i.e 1.26 vs 1.20 etc) but that must be negligible for the ECU. I haven't driven it yet but will hopefully get it out tomorrow. Thanks again LL and 240Z Twin Turbo.
 

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UPDATE:
Removed the passenger side intake with the faulty MAF sensor position and installed the new one that was over-nighted by Cobb. Attached is the data log after install. Engine ran fine. No CEL. The MAF readings on the data log are about 4-7 hundredths off from side to side (i.e 1.26 vs 1.20 etc) but that must be negligible for the ECU. I haven't driven it yet but will hopefully get it out tomorrow. Thanks again LL and 240Z Twin Turbo.
Glad to hear this was resolved and the real thanks goes to LL, who will hereby be referred to as "The Oracle."

The bank balance is slightly off, but not bad so just do a bank balance using your V3 after the car is warmed up.
 
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