[stellae90]

Hello guys! Over the course of a few months I have started to work on my n55, adding bolt ons such as a vrsf charpipe, bms intake, vrsf fmic, vrsf catless dp, and a mhd stage 0 tune and a xhp stage 3 flash, I run on 89 with a burble tune. For a month or so it ran flawlessly with perfect cold starts and pretty much no problems.

Recently I started noticing a shaky idle that occurs during some cold but also when I restart car when hot. In park it shakes here and there but hasn't ever died yet, although I haven't been driving it much.

I recently changed the oil to 5w-40, not sure if that has anything to do with it as it was driving fine after oil change and is now acting weird.

Id like to mention the car drives fine and doesn't really feel like it has power loss but I don't want to go WOT with this problem occurring lol.

When I first noticed this problem, it threw me these codes:
3774 - Air volume, plausibility: Air volume too high.
2BEA - Mixture control: Fuel-air mixture too lean, large deviation.
(And a shadow code - 2C42 Mixture control: Multiple fault).

I cleared the codes to see which one would pop back up first, but it did not come up for a bit. The next day it started fine with no problems and I drove around for a bit. I then restarted car and the problem returned. I threw the following codes below:
28AO - Air mass system, plausibility: calculated air volumes in air intake system implausible.
(And a shadow code -2820 Absolute pressure sensor, intake pipe: Multiple fault).

The shadow code points towards the intake, I installed the intake around 54,000 miles and am now at 60,000, Maybe change filter?

Then something terrible happened the next day that made me change my mind about the intake.

My car was driving fine the next day with a cold start that was fine (I uninstalled mhd and burble tune at this point which seemed to help a little). Then I restarted after a workout and boom very shaky idle. I threw multiple misfire codes and will list below this paragraph. I realize it could be spark plugs, coils, fuel injectors, or even a valve cover gasket (although I got replaced at 51k). I ordered NGK spark plugs and am gonna see if that does anything, I will try to take some logs of idle today and see if that will give me any information.

(I do also realize it could be a maf, or some other dirt sensor or vacuume leak, but I want to stress the car drives fine and is not loosing boost).

List of codes:

2774 - Air volume, plausibility: Air volume too high.
28A0 - Air mass system, plausibility: calculated air volumes in air intake system implausible.
2BEA - Mixture control: Fuel-air mixture too lean, large deviation.
2EE2 - Combustion misfires, several cylinders: Damaging exhaust gas after starting up.
2EEC - Combustion misfire, cylinder 3: Damaging exhaust gas after starting up.
2EF0 - Combustion misfire, cylinder 4: Damaging exhaust gas after starting up.
2EF3 - Combustion misfire, cylinder 5: Damaging exhaust gas after starting up.
2EF6 - Combustion misfire, cylinder 6: Damaging exhaust gas after starting up.
2EFE - Combustion misfires, several cylinders: Damaging to catalytic converter or damaging exhaust gas.
2F01 - Combustion misfire, cylinder 3: Damaging to catalytic converter or damaging exhaust gas.
2F02 - Combustion misfire, cylinder 4: Damaging to catalytic converter or damaging exhaust gas.
2F03 - Combustion misfire, cylinder 5: Damaging to catalytic converter or damaging exhaust gas.
2F04 - Combustion misfire, cylinder 6: Damaging to catalytic converter or damaging exhaust gas.

- DME shadow (inactive) codes -
2820 - Absolute pressure sensor, intake pipe: Multiple fault.
2C42 - Mixture control: Multiple fault.

I'm only 17 and owned this car for a few months and been trying to learn a lot from it and it sure has been testing me, just want to double check with the pros. Please let me know if you guys have any idea or tips for diagnosing, and thanks for your time.

-Stella

[houtan]

Did you ever figure this out?