r/335i

I have a 2009 e90 335i that randomly and inconsistently enters a sort of limp mode. However, the car doesn't actually go into limp mode (no lights on the dash, and the car can still reach highway speed). The car limits itself to 3k rpms, shifts very slowly, and won't build boost until 6th gear. While that's happening, the fan runs at full speed and won't go back down until the car is turned off.

It will do this regardless of the oil or coolant temperature, and sometimes it happens a couple of minutes after a cold start. The car is tuned with MHD and XHP. I've tried de-tuning the car, and it still happens.

The car was recently in the shop (this was happening before and after its visit to the shop), and while there I had my turbos inspected, a compression test, and an exhaust/boost leak test, which all came back with no issues. The car has no codes or shadow codes. Otherwise, the car performs and acts as expected.

I will try to get a video of this ASAP, but if anyone has any ideas, all the help will be greatly appreciated.

P.S - The car was in the shop for a valve cover replacement, replacement of the JBE due to water damage, a full cooling system overhaul (new water pump, expansion tank, and all the hoses/fittings were replaced), oil change, and new NGK spark plugs.

parts list

-index 12 injectors

-vrsf charge pipe

-50mm tial BOV

-upgraded fuel pump (idk which one previous owner had it installed at the same shop)

- vrsf 7.5in intercooler

-cold air intakes

hello hello i drive a 09 335i and am seeking some help

a week ago as i was warming my car the idle shot up to 1k out of nowhere and then settled back at 600ish where it normally does, i shake it off as a misfire but i still go to c&c, and when i get there it starts to do it when i parked

when i left it kept doing it too, on repeat, at stops and when i got home and put it in park, something was obviously wrong at this point but it was a controlled spike / fall so i was just got home and chose to deal with it later in the day

ff and i start it up like 5 ish hours later and it dies before i can even realize whats happening, the idle was was rougher than previously described and the exhaust genuinely sounded like it was choking on itself

i have no codes and no dash lights but i used my code reader and mhd to clear codes

it stabilized at first after both times but then started doing it again, super rough kept shooting up to try and stabilizing but would fall down sounding like it was choking

i’ve smoked tested turbo and vaccum side, nothing

have checked both vanos solenoids

- gets interesting here cause there’s some visible scratching near the holes but looking as hard as i could i maybe saw one piece of metal in my oil filter

am i smoke testing vaccum side wrong?

dirty maf sensor or do i need new vanos solenoids?

i kinda dont know what to do past this point, i just got a new valve cover installed a little over a month ago and im worried that may be involved and perchance the pcv system already cooked