Technical Persistent Cylinder 6 Misfire!

[purpol e9deh]

07 E90 335i 6AT posted this to e90post but not much happening over there so I’ll try here for as much info as I can get

I originally chased a misfire all the way around the car (bad HPFP and coil on cyl 3), I replaced my entire fuel system besides injectors 1-4 and fuel pump control module, all my coils with dinan coils, new plugs, HPFP, VANOS solenoids.

I get 800-900 psi or more around idle at my rail. 2500+ when I rev it, and lpfp shows 70-80 psi. Index 10s all around so I replaced 6 with index 11 and cyl 5. Still misfires so I swap 5 and 6 and no difference. (Coded when swapped).

Misfire cylinder 6 code

INPA shows richer AFRs on bank 2, it is knocking BADDDD but here’s the thing; the knock comes and goes. Sometimes it’s “papapapap” misfiring or sometimes it’s “KANGKANGKANGKANG”. INPA also shows running roughness % in cylinder 6 is WAY out of whack, 1-5 barely move when I rev and 6 goes all over the place.

I compression tested my motor and got
1 170psi
2 160psi
3 165psi
4 163psi
5 160psi
6 165psi

Valves have some carbon on them but cylinder 6 is by far the best. My intake manifold is clear and clean. I took it off.

My turbo seals are blowing oil into the intake side of the engine, I’m waiting on some new seals to rebuild.

I’m stumped. I’m thinking it’s either: ECU issue (it’s an msd80) Valve sticking?, All the oil only going into cylinder 6? It ran fine before with the oil leak into the intake.

It will get worse and better. It sounds like the DME is tapering fuel or timing at idle when it’s knocking in cylinder 6.

Have not replaced the 02 sensors. But wouldn’t that make more cylinders in bank 2 misfire if it had a bad 02? (Primaries are only used as it’s tuned by twisted tuning, flashed with MHD)

Here’s links to some videos where it shows the 02 levels and knocking:

And

I’m stumped. Cars been down for two months now and had many paycheques put into with no result. lol

New to n54s so Any help appreciated!

 

[Jern54]

Post a log and upload the csv file if possible
Monitor default channels + STFT 1+2, LTFT 1+2 and Fuel Mode

Start with:
-Plugs
-Coils
-Injector

 

[purpol e9deh]

Post a log and upload the csv file if possible
Monitor default channels + STFT 1+2, LTFT 1+2 and Fuel Mode

Start with:
-Plugs
-Coils
-Injector

Gotcha. Appreciate the help!

I’ll mix around my injectors and plugs and coils. New dinan coils as of last week and OEM Bosch plugs, as well as the two index 11s but hey I get faulty new parts at work here and there.

I’m assuming those channels are in INPA?
I have MHD and a super license but I have a faulty scanner that can’t connect with the engine running. It also has issues resetting parameters and I can’t reset my fuel parameter after recoding my injectors.

And where can I find that csv file at? Is that the file I can pull off the car with MHD?

Sorry if I misread / misinterpreted what you said as I’m an n54 noobie

I do have another android reader called Torque Pro that can read Fuel trims if that’s what u mean. It was as high as 14% when driving, I got a video of it but I’ll try and get a log either through MHD (if my replacement scanner is here) or torque pro.

 

[swellengear]

You can test your DME quite easily. You need to disconnect the battery, remove DME from the car, open it up, and then you can measure the mosfets inside. Set your multimeter to read continuity. - it should only beep on the centre pin. If one or both of the outer legs beep, the mosfet is cooked. Quite common on the MSD80.

Video:

 

[Greenie]

index 11 = around 10 years old injectors?
where did you purchase them?
take photos and post them here.

 

[purpol e9deh]

So I cranked the car over by hand and put air to the cylinder and saw this on cyl 6

So yeah. Carbon buildup. Cleaning will solve this? Or could this be a bent valve too?.

I tested the ECU. It was ok. Popped it apart and tested the MOSFETS and they all tested ok. I put the DME back together and back in the car.

I checked my spark plugs when I removed them and they didn’t seem to have fuel on them. Cylinder 3 is the blackest. I’m guessing this has to do with the oil being blown everywhere plus carbon and gunk keeping valves partially open?

The plugs are a month old and a few are black. Coils are fine, swapped them around again before I took it apart and noticed no difference.

I got to rebuild my turbos. The seals are toast and letting oil get blown all around the charge pipes and exhaust. I have 17ts that match with the OEM P/N But they’re for the TD03 housing turbos, not the td04 the 17ts.

If it’s the wrong size I’ll use a pair of stock turbos that need seals my friend gave me and flash MHD stg2+

Index 11s were listed as “refurbished” on marketplace. A guy had them in his car and bought 12s to fix a misfire but it turned out to be an 02. Swapping 5 and 6 which I bought from marketplace doesn’t result in a change in cylinder 6 misfire changing.

Is it worth popping the valve cover off and looking for any issues in there with springs?

I gotta run the car to move it onto the hoist to do turbo seals. I’ll log some stuff then.

Appreciate the help!

 

[Greenie]

Real circus.
These injectors CANNOT be refurbished or cleaned.
Install brand new injectors first.
If the 5th and 6th swap didn't help, it seems the 4th is leaking.
Anyway, spark plugs confirm that your injectors are total crap.

p.s. carbon buildup is NOT the cause of this issue.
Your stg2 COULD be (because destroyed software is one of the most popular issues).
So, install correctly working injectors; restore stock software, install correctly working turbos; perform re-adaptation of the engine and everything will be fine.

 

[purpol e9deh]

Appreciate guidance. I’ll go through and pick up some index 12s when I can. I beat on the car I might as well take care of it and it’s a matter of time till the 10s and 11s fail.

I’m just concerned that the intake valve there popped back open? When I cranked it last night and in the video it seals for a second then pops open. Is it worth popping the valve cover off and looking at the springs?

I need to clean the carbon lol it’s a lot worse in the other cylinders. They got hella chunks in the ports.

I bought the car with these 17t turbos and a tune on it. I’d like to not lose access to that tune if I’m switching the map to stock. Is there any way I can pull that map off and save it?

 

[Greenie]

btw, your first video doesn't show knocking. It's the mechanical efficiency of cylinders.
Cylinders are numbered by firing order. Reduced value - increased mechanical efficiency.
And yes, the 6th cylinder shows incorrect efficiency - the injector is leaking, and adaptations are incorrect.

 

[purpol e9deh]

btw, your first video doesn't show knocking. It's the mechanical efficiency of cylinders.
Cylinders are numbered by firing order. Reduced value - increased mechanical efficiency.
And yes, the 6th cylinder shows incorrect efficiency - the injector is leaking, and adaptations are incorrect.

Oh! Ok I understand now.

2 things.

1. My MHD stopped letting me reset adaptations like the other night. Not sure why. Can I do this in INPA?

2. I coded my injector and the value shows like .2 lower on both ends than coded value. It did this before with the old injector.

 

[Greenie]

Coded and confirmed values differ. It's normal.
The first step - using proper software (INPA, ISTA, etc.).
Also, re-adaptation is NOT clearing of old adaptations!
If these injectors are ''refurbished'', their coding is crap/fake.

 

[BillV]

Appreciate guidance. I’ll go through and pick up some index 12s when I can. I beat on the car I might as well take care of it and it’s a matter of time till the 10s and 11s fail.

I’m just concerned that the intake valve there popped back open? When I cranked it last night and in the video it seals for a second then pops open. Is it worth popping the valve cover off and looking at the springs?

I need to clean the carbon lol it’s a lot worse in the other cylinders. They got hella chunks in the ports.

I bought the car with these 17t turbos and a tune on it. I’d like to not lose access to that tune if I’m switching the map to stock. Is there any way I can pull that map off and save it?

If you decide walnut blast, be super careful that valves are closed. I screwed my engine up, getting shells into cylinder. Wasn’t a total shit show, well maybe it was, but as a result of pulling head off, I rebuilt turbos, new orings in coolant and oil lines to turbos. Major source of oil leaks BTW.
companion cylinders on the n54: 1&6, 2&5, 3&4.

 

[Nosrok]

Before you go spending 3k on new injectors, try swapping the front 3 for the back 3. Remember to re-code them when replaced and reset adaptions/octane. Without port injection you should a spike of 200+ in your AFR when getting off throttle, if you don't then it's. Assign an injector is leaking.

Also you can clean these type of injectors and that's usually what is marketed as "rebuilt" some places will even provide new flow numbers to go along with the tested injectors. It's a few hundred bucks for all 6 but if the problem persists on #6 it's highly unlikely that you have an injector issue.

Check the plug for the injector, it could have been damaged.

Finally the msd80 dme can fail on the bottom board and cause misfire issues as well. It's not as common but it happened to one of my cars. The MOSFETs had been replaced and tested good but I couldn't resolve an intermittent misfire.

 

[Greenie]

Forums are a perfect place where people with zero understanding to place their opinions, ideas, and thoughts.

 

[purpol e9deh]

Ok so I have returned!

My car is in pieces and honestly I’m not even sure where exactly the misfire would have came from as this bozo before me did half the job of putting the turbos back in.

Broken vac lines everywhere, waste gate line was OFF, yadda yadda. Fixing those.

Now let alone turbo seals; they’re toast. The front turbo shaft wiggles and its seals are toast. Oil everywhere, in the exhaust, intake, and all over the turbos. Rebuild time!

I’m throwing some new primary 02 sensors in as well as the old ones were SOAKED in oil.

When I go to prime my turbos after rebuild (cranking but no start) I will attach my injectors to the rail facing outwards of the engine, crank it over with rags underneath and check for leaks when I build pressure.

Still hunting for some index 12s.

I’m on my second injector for #6 and boom!

Misfire jumped to Cyl 5 (on code reader) and I’ve swapped all my coils and plugs and verified they work.

So far it’s mostly been on back bank of cylinders. I’ll knock off the rest of the replacement parts in my turbo rebuild and give another update.

I’ve seen some shops in the states and now one in BC, Canada (near me) that cleans and tests n54 injectors. I’ll swap the banks of 3 around and watch my AFRs before I drop any money though.

Appreciate the tips again guys!

 

[purpol e9deh]

If you decide walnut blast, be super careful that valves are closed. I screwed my engine up, getting shells into cylinder. Wasn’t a total shit show, well maybe it was, but as a result of pulling head off, I rebuilt turbos, new orings in coolant and oil lines to turbos. Major source of oil leaks BTW.
companion cylinders on the n54: 1&6, 2&5, 3&4.

Cleaned my intake with a pick, brush, brakeleen and carb clean and WOW it looks like new. Walnut would definitely be faster but hey it was free.

 

[RogerThat]

Hello, l too was chasing a missfire from no.6 was Intermittent, then became constant.
Was O2 sensor before cat.
I have a 08 335i msport wagon. Catless DP’s.
I found when l disconnected the grey wire coming from rear of engine along right side of rocker cover at square connector, the engine ran smoothly. The other connector lead is black. That is front bank before cat. The after cat sensor connectors are down under the trans. Front edge of pan.

 

[RogerThat]

O2 sensors can be used again, if dirty or oil soaked, by soaking in toilet cleaner.