[ksw2pro]

I have 2009 335i X Drive. The vehicle has 95k Miles.
The vehicle starts with no problems or hesitations. It idles perfectly, but when I take it out for a drive, It starts with a half engine light and limp mode. Then it starts to misfire severely. It shakes so much I can hear my heat shields rattling under the car. If I keep driving it like this, I will get some popping noise, presumably exhaust backfire from unburnt fuel, and I have no power. 0-40mph(max I can go) takes literally 30 seconds. Then if I turn the car off, and clear the check engine light It has a very smooth idle. Revs with no problems to 7-8k RPM in park.
It currently has codes misfire cylinder 1 2 and 3. It usually starts off with Misfires 1 and 3. Then after some acceleration, cylinder 2 pops up. If swapped coils with no change in symptoms. If replaced plugs. If changed out the injectors for cylinder 1 2 and 3. bank 1 pre cat o2 sensor replaced as well. Nothing seems to change.
Currently, Im cleaning out my VANOS solenoids.
Next week, Im scheduled to have my intake valves cleaned.
and my scanner will be coming in next week so I can have a good read at hidden codes. Will update!! but, If anyone has any insight on whats going on, Please help. Im getting tired of throwing money at this car.

[Ravenseal]

Come back when you've done everything you're supposed to in order to address misfires. Intake valve, spark plugs, coil packs, injectors. Lol. None of us have a magic solution for them.

[Gohan335i7]

Here it is! The Magic Wand! 🙌🖖🙌🖖 Your car is ready sir. Lol. I agree with the above . Plugs, coils, injectors, valves first. -Gohan335i7

[mxchris727]

Sounds like a failing DME

[Swizzie7]

Any Mods??

[ksw2pro]

Originally Posted by Swizzie7

Any Mods??

stock with dci.

[ksw2pro]

UPDATE: Just had my intake valves cleaned. Still the same.
Coil packs had been swapped out and misfire persists in the same cylinders. Injectors had been replaced and coded.
Sparks plugs were the first to be replaced.
My D-can cable broke a few weeks back and I have another one on order coming in next week. Ill post logs as soon as I get the cable.
Today, I will be removing my DME to test mosfets.

Update 2: I took a closer inspection at the code reader and it seems like Cylinders 1 and Cylinders 3 misfire first. And about a half mile later, Cylinder 2 code appears.

Originally Posted by Ravenseal

Come back when you've done everything you're supposed to in order to address misfires. Intake valve, spark plugs, coil packs, injectors. Lol. None of us have a magic solution for them.

I'm OBVIOUSLY following the misfire guide.... I was asking for insight on things that I should check out other than the things I had listed out or similar instances. Not looking for a magic solution. If you have nothing useful to post, please refrain from posting. Your post helped me in no way other than to inform me that you had not read my post.

[ksw2pro]

Originally Posted by mxchris727

Sounds like a failing DME

Thank you for actually posting something for me to try.

[muncie21]

I went through a similar issue recently.
Do yourself a favor and double check everything you recently changed first.

• Pull the plugs to see if they are wet
• Make sure the coils are completely seated
• Reset adaptations
• Verify the injectors are coded correctly

After you've done this, I'd start looking at the mosfets in the DME. The mosfets themselves are cheap but it's easy to fry the DME if you aren't used to soldering around delicate electronics. Toasting the DME will indeed be an expensive proposition.


Best of luck, let us know how things turn out...

[924er]

Do what's stated above.

Also check your DME, o2 sensors and clean your VANOS

[ksw2pro]

Originally Posted by muncie21

I went through a similar issue recently.
Do yourself a favor and double check everything you recently changed first.

• Pull the plugs to see if they are wet
• Make sure the coils are completely seated
• Reset adaptations
• Verify the injectors are coded correctly

After you've done this, I'd start looking at the mosfets in the DME. The mosfets themselves are cheap but it's easy to fry the DME if you aren't used to soldering around delicate electronics. Toasting the DME will indeed be an expensive proposition.


Best of luck, let us know how things turn out...

i will be checking the coding on injectors when my cable gets here.

there seems to be a little bit of wetness on my spark plugs 1 2 and 3. it was the same way before i replaced my injectors. 4 5 and 5 are still dry

i removed my dme this morning and checked the mosfets for injectors 1 2 3. and it seems. like 1 and 3 are shorted. will be sending it out to be repaired today.

Thank you very much for your insight

[ksw2pro]

Originally Posted by 924er

Do what's stated above.

Also check your DME, o2 sensors and clean your VANOS

checked all4 o2 sensors. found the bank 1 precat to be a little fouled and replaced it last week. still no change

vanos for both intake and exhaust have been thoroughly cleaned with parts cleaner and a rag. was very careful with it last week. no change

dme was removed this morning. it seems like 1 and 3 mosfet is toast, but will know for sure when i send it out to the repair shop. will update

thank you for your input

[muncie21]

Originally Posted by ksw2pro

dme was removed this morning. it seems like 1 and 3 mosfet is toast, but will know for sure when i send it out to the repair shop.

Best of luck and let us know how things turn out

[fly5280]

Have you considered a vacuum leak?
Just thinking... It could cause the misfire under load like you're experiencing.

[ksw2pro]

Originally Posted by fly5280

Have you considered a vacuum leak?
Just thinking... It could cause the misfire under load like you're experiencing.

Oh!!! good call! ill check all my lines. i did check my valve cover, charge pipe, and intake manifold for possible cracks or leaks. but not the smaller lines. thanks!

[Spacecpe]

My money is on the mosfets.. vacuum leaks don't cause crazy limp modes.. usually if u go through plug, coil, injectors and walnut blast there's nothing left but the DME..

[ksw2pro]

Originally Posted by E90 M335i

My money is on the mosfets.. vacuum leaks don't cause crazy limp modes.. usually if u go through plug, coil, injectors and walnut blast there's nothing left but the DME..

does anyone know why these mosfets go bad? moisture? wear and tear? faulty injectors?

[Socket]

Originally Posted by ksw2pro

does anyone know why these mosfets go bad? moisture? wear and tear? faulty injectors?

I think it has something to do with they way they are soldered up, they flex and crack?? or is that the atm gear stick I cant remember

[Ravenseal]

Originally Posted by ksw2pro

I'm OBVIOUSLY following the misfire guide.... I was asking for insight on things that I should check out other than the things I had listed out or similar instances. Not looking for a magic solution. If you have nothing useful to post, please refrain from posting. Your post helped me in no way other than to inform me that you had not read my post.

Ok. So finish following the guide