[sl0w35]

Need help identifying an issue with my car, ive been chasing a misfire for months now. Purchased the car from a family member. Had some rough starts and misfires under load. I went the regular route of replacing plugs and coils, bosch plugs and coils. Didn't seem to clean up my misfire, I then realized that the plug wells were filling up with oil due to the leaky valve cover. I then replaced that, still no change. Next I went with a set of index 12 injectors... Still no change.... now I went to my last step with cleaning the intake. STILL NO CHANGE. I'm stumped at this point. The car also has catless down pipes with a tune from some random guy my cousin went to. I'm thinking its an issue with the tune, now I'm wondering how to revert back to the factory map then have someone reliable tune my car.

Car also dose not have any fault codes for HPFP or LPFP. The car has a good cold start, then when I drive it, it shifts hard through gears with some hiccups, then when the car is parked and i restart the vehicle it has trouble idling and suddenly revs up to about 3k finally running normal.


I just want to enjoy this car. Any advice from someone on here?


2007 335xi e90 with about 141k

[witty]

try removing the tune and revert it back then let us know if it still happens!

[sl0w35]

Originally Posted by awesu

try removing the tune and revert it back then let us know if it still happens!

I will definitely let you know… kinda stumped on removing the tune. Wondering if MHD revert back to stock feature is free and will let me just use it? Puzzled.

[witty]

Originally Posted by sl0w35

I will definitely let you know… kinda stumped on removing the tune. Wondering if MHD revert back to stock feature is free and will let me just use it? Puzzled.

sadly i think your forced to buy the license to flash to stock i think

[sl0w35]

Originally Posted by awesu

sadly i think your forced to buy the license to flash to stock i think

The full license or just the flasher?

[Nolan2221]

Originally Posted by sl0w35

The full license or just the flasher?

I would try reverting the DME back to stock through MHD. If that doesn't work I would look into your valvetronic system.

[Ozzie335i]

As you bought it from a family member see if he still has the app loaded, or can temporarily load it to give you a hand. Lunch or a few beers later hopefully you'll have your answer.

[Torgus]

Reflash to stock or a OTS map and see what happens.

Did you gap the plugs?

Is the misfire always on the same cyl at the same RPMs?

Have you changed out all of the vacuum lines? It's cheap.

I would remove the coil packs and plugs, swap em around, see if there is any change. It is quick enough to do. Reflash to whatever then log with MHD. Upload logs to datazap and post log here of both cold start idle, warm idle, and WOT where you get the misfire.

[anjuna]

I'd be willing to bet coil packs.

You may have replaced them, but I only trust OEM and the "t00n" you're running can kill them quickly if not set correctly (dwell times)

[PS2N54]

(if back to stock tune, and no misfire codes, but you feel it misfiring)

i dont think the gear swift and misfire issue would be related given parts replaced. shift part could just be bad actuator solenoids on seals mechatronic unit.

- make sure coils+plugs good and are authentic (fake bosch going around). a heavy tune would kill them quick even if authentic.
- compression test the cylinders to make sure piston rings good (if valves cleaned properly, doubt it would be leaking from there)
- check VANOS and vanos check valves, it kinda sounds like it might end up being them or oil lines to them caked with sludge if car not properly maintained.

[sl0w35]

So plugs and coils are new and I swapped coiled around to see if it changed anything. Still the same problematic cylinders. I’m guessing tune, and the family member had it tuned and I believe it was Mhd, I contacted the tuner and he wanted nothing to do with me cursing at me. Also plugs are gapped correctly.

I’m guessing I’m going to have to purchase an mhd license to revert back to the factory map.

I should also look at the vac lines and make sure I’m none are leaking.

[whyzee125]

Definitely start by reverting to factory tune and reading codes to see which cylinders are misfiring. I'd just get MHD, you'll likely want it in the long run if you're keeping the car anyway for monitoring, code reading/clearing, and tuning.

ALso, is this n54? I see you said index 12 injectors so I'm guessing n54 but this is the n55 section so it would help to know which engine.

[Kevin39]

Originally Posted by whyzee125

ALso, is this n54? I see you said index 12 injectors so I'm guessing n54 but this is the n55 section so it would help to know which engine.

Yep, you're right. At the bottom of his first post it says 07 E90

[whyzee125]

Originally Posted by Kevin39

Yep, you're right. At the bottom of his first post it says 07 E90

Totally missed that, thanks!

In that case, it could be a mosfet if it's a constant misfire

[sl0w35]

I didn't post in the right section? Whoops

So what I'm willing to do next step is replacing both VANOS Solenoids, the front of the motor leaks oil where they are located. If that does not work I will revert to the factory map. I need to get rid of this bootleg tune. If the original tuner is not willing to help me I'm sure he has a bad rep.

If that does not work i will go through FCP and grab more coils, i purchased 2 from them thinking that i had purchased some faulty ones through amazon. I swapped them around, and it did not change a thing.

But appreciate all the help everyone. I will keep ya'll updated. I wish I could enjoy this car.

[sl0w35]

So changed vanos, seems to help with driving getting hesitation, still misfire on start. I’m reverting back to the factory map.