Poor Idle, Lean/Misfire codes after Stock Intake install

dinocrest

Lurker
Apr 27, 2021
16
2
0
Hello!,

I am reverting my car back to stock for inspection and swapped out my Injen Intake for a stock one the other week. Immediately after install the car begin to run rough or not idle at all. It threw a ton of misfire and lean codes too. I was able to "fix" the idle issue mostly by unplugging the MAF. Although even with MAF unplugged the car still occasionally will die at idle and throw the codes.

I have tried cleaning the MAF, and replacing it with another MAF and the problem persists.

Intake seems to be installed correctly. I have also reset idle adaptations on MHD and it seemed to help just a little at first but still having issues.

After a little bit of driving the car will smoothen out and run mostly fine with MAF unplugged but I'm still getting codes.


Stock Downpipe
MHD Stage 1
Stock Intake
VRSF 7.5 FMIC
VRSF CP

Thanks!
 

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SLOWESTN54

Lieutenant
Feb 9, 2021
738
477
0
22
B.C. Canada
Ride
2007 E92 335i / 2008 E60 535i
I'd start off with checking all the pcv hoses that connect to the intake itself possibly ones cracked or disconnected
 

wheela

Sergeant
Jun 4, 2021
407
235
0
Twin Cities, MN
Ride
2015 e84 X1 35i Msport
One particular hose that likes to crack is this little corrugated one here, that would definately be worth checking. Also, it seems a little strange that you didn't have problems with the injen intake, but are having problems with the stock intake. Usually it's the opposite with aftermarket intakes and OTS tunes, as the HFM tables in the OTS tune aren't adjusted for a different intake duct. If you can't find any leaks or damaged connections, perhaps there's still some adaptation that MHD doesn't clear that needs time to adapt back to the stock intake🤷‍♂️
 

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dinocrest

Lurker
Apr 27, 2021
16
2
0
One particular hose that likes to crack is this little corrugated one here, that would definately be worth checking. Also, it seems a little strange that you didn't have problems with the injen intake, but are having problems with the stock intake. Usually it's the opposite with aftermarket intakes and OTS tunes, as the HFM tables in the OTS tune aren't adjusted for a different intake duct. If you can't find any leaks or damaged connections, perhaps there's still some adaptation that MHD doesn't clear that needs time to adapt back to the stock intake🤷‍♂️
Yeah I remember that hose, I had to replace it the first time around when I cracked it during Injen install. I'll check it again and see if I cracked it this time around. If the hose is fine do you have any idea if there's any other adaptations I should clear thru the MHD app that could solve this? I've driven the car about 800 miles since the stock intake install I figured it should of adapted by now.
 

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wheela

Sergeant
Jun 4, 2021
407
235
0
Twin Cities, MN
Ride
2015 e84 X1 35i Msport
Hmm... I'd think that should be plenty of miles to re-adapt. Did you reset the intake mass flow adaptation? I haven't had to reset any adaptations yet, so I'm not the best person to ask. But since things improve when you unplug your maf that's why I mention the intake mass flow adaptation.
 

dinocrest

Lurker
Apr 27, 2021
16
2
0
Hmm... I'd think that should be plenty of miles to re-adapt. Did you reset the intake mass flow adaptation? I haven't had to reset any adaptations yet, so I'm not the best person to ask. But since things improve when you unplug your maf that's why I mention the intake mass flow adaptation.
Yes I did reset that, and it seemed to fix the problem just a few min or so. But quickly came back
 

SLOWESTN54

Lieutenant
Feb 9, 2021
738
477
0
22
B.C. Canada
Ride
2007 E92 335i / 2008 E60 535i
The fact that it runs better with the maf unplugged shows that there is a leak after the maf sensor. id check for crack in the intake itself or maybe a pcv line that's not in right
 
  • Agree
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