X5 35D misfire help!! (Solved)

[Colbyt93]

Good afternoon everyone, I've been chasing what feels like a misfire and I'm at a loss so I'm looking for some insight/help.

So a little background on my x5, it was tuned/fully deleted by Kassel tuning as well as new valve cover gasket about 2 years ago with zero issues up until now, I replaced the low pressure turbo last year which was the only major hiccup since owning and it's been running great since up until a few months ago it started to feel like it had a very slight misfire/rough idle but it was only when it was up to running temp, from a cold start up until at running temp it wouldn't skip a beat but it progressively got worse and now it's to the point it runs very rough and smokes at idle but only when hot, and if you bring rpms up over 1200 the miss/smoke goes away

It has not thrown a code this whole time so I don't really have a smoking gun to point me in the right direction, so I decided to do some tune up maintenance and this is what I've done so far.

Replaced vacuum lines
Had injectors sent out to S&S tested
Replaced #3 injector (failed resistance once hot)
New crush washers
Coded and reset adaptations once installed
Fuel filter
Changed glow plugs since everything was off
Compression is good across all cylinders
New gaskets on intake manifold
Thermostat

Using protocol I can see that cylinder 5 seems to be missing the most, I swapped injectors 1/5 and reset adaptations to see if the misa followed and it did no, II've checked all my vacuum line several times and even pulled intake off to make sure the gaskets were all in place so at this point I'm kinda lost. I appreciate any info you guys can pass along to help, I'm new to the forums so I apologize if this isn't posted in the correct spot.

[jbash87]

Hmm. Seems like you've done most of the normal things already. I've heard in gassers you can get misfires due to carbon buildup in the intake manifold and intake runners. Have yours been cleaned?

Check out the NABDOG (North American BMW Diesel Owners Group) group on facebook. They might be able to help you a bit better with weird diesel specific issues.

[Colbyt93]

As far are carbon build up I think the previous owner did the cbu cleaning because when I had the intake off I bore scoped it and the valves/intake are almost spotless

[jbash87]

Originally Posted by Colbyt93

As far are carbon build up I think the previous owner did the cbu cleaning because when I had the intake off I bore scoped it and the valves/intake are almost spotless

Bummer. Well not bummer because they're clean, but bummer because that isn't the issue it seems.

Could the intake manifold gaskets for cyl 5 be pinched or something? Maybe when things get to temp they allow air to escape? I'm just throwing stuff out there at this point.

Check out the NABDOG group. Post the Protools code and explain exactly what you've explained here.

[Colbyt93]

I've looked on a few forums but nothing really comes up similar to my dilemma lol, I've checked everything about 3 times I take wise and everything gasket wise looks good, the only od thing I've noticed is the flow rate on the MAF is almost half of what my 335D reads so I'm going to swap mafs between the 2 and see if that does anything

[wcs531]

Are the swirl flaps deleted? Stock swirl flaps are known for being leaky and apparently many of the delete kits can leak slightly as well because they have somewhat small orings. I went with these to replace the orings on my tunemyeuro swirl flap delete kit:
https://www.oringsandmore.com/fkm-o-...minimum-2-pcs/

[Colbyt93]

Yeah they are deleted and I was thinking about checking them for leaks since I'm kinda at a loss

[wcs531]

A video capturing the engine noise may help someone identify the issue. Also show how much smoke.

Smoke is more often than not one of the turbos going but I don't know how that would cause misfires or rough idle

[Colbyt93]

I'll have to do that next time I take it for a drive, and the previous owner replaced the high pressure turbo shortly before I bought it and then I replaced the low pressure about a year ago, I checked all the intercooler piping and even the exhaust side of the low pressure and the turbo seem to be okay and the smoke is definitely a grayish white like unburnt diesel and it smells very strongly of diesel not so much oil

[RL18]

What color is the smoke?

Edit didn’t see the comment above lol ^

[wcs531]

One thing I keep thinking about is maybe a bad valve spring somehow? Strong enough to hold the valve closed during the compression test with the engine off, but when the engine is running and hot maybe its not rebounding fast enough to close the valve fully.

This doesnt make sense that it would go away at higher rpms though.

[Colbyt93]

Yeah I was thinking valve also but it's tough to say, and like I mentioned earlier from cold to operating temp there is zero issues, after it's been running and everything is up to temp is when it begins to act up. tomorrow I'm going to try swapping mafs between my x5 and 335D mainly because at operating temp the 335D reads almost 3x the amount of air flow than the x5, I know every engine is slightly different but that's the only thing that has really stood out to me and id imagine being the same engine it would be closer to the same parameters.

[RL18]

Originally Posted by Colbyt93

Yeah I was thinking valve also but it's tough to say, and like I mentioned earlier from cold to operating temp there is zero issues, after it's been running and everything is up to temp is when it begins to act up. tomorrow I'm going to try swapping mafs between my x5 and 335D mainly because at operating temp the 335D reads almost 3x the amount of air flow than the x5, I know every engine is slightly different but that's the only thing that has really stood out to me and id imagine being the same engine it would be closer to the same parameters.

X5 intake flows much better than 335d. I change my Maf sensor every year, they suck.
I would start with the easiest thing to do and ask Kassel to update or check over the tune for you. Other than that I would say a stuck injector but you said the problem didn’t follow the injector when you switched them.

Could also give the injector plugs a check over. I know when my vcg was done there was enough dielectric grease in the plug to not let the plug seat all the way.

[Colbyt93]

Well my 335D was showing more air flow than the x5, I also removed both air boxed when I was looking at what the MAF was reading so I had both reading with zero restrictions, and yes everything injector wise is good, they were tested/cleaned/balanced by S&S, with 1 new injector being Installed in cylinder 3. If the MAF doesn't change anything being swapped and checking the swirl flap deleted doesn't show any signs or leaking from a bad oring like someone mentioned, I may venture into checking a vcg, but Im going to contact Kassel this week if I get a chance and run this by them, im like 2-2.5 hours away from them so I can always drive it down if that's something they'd recommend

[Colbyt93]

Sorry I forgot to mention, I did check all the plugs/wiring for any fraying/cracks and everything seems okay, I do have another harness from a parts car I considered swapping to see if it would make a difference, I just wish the damn car would throw some kind of code so I have something to focus my efforts on 🤪😂

[DialedIn]

I heard about a similar misfire issue and it turned out to be an electrical issue and nothing wrong with the engine.

It was a bad component on the circuit board for the ECU.

[Colbyt93]

I swapped MAF between my 335D and x5 with no difference in readings and then driving today it finally threw a code for cylinder 4 misfire, so I pulled the intake off, checked swirl flaps, they all looks fine and then since I was there I swapped injectors 4/1, coded them/reset adaptations and it didn't change anything, still is missing on cylinder 4. With everything mechanical/compression/injectors being good im starting to wonder if it's something electrical, if cylinder 4 wasn't getting a signal to inject id imagine cylinders 3/5 would inject more fuel to try and compensate but im not 100% sure. ive had crank sensors on gas engine cause misfires intermittently when they got warm due to a change in resistance or something making it read wrong I'm guessing, don't know if that's something possible on the m57 but I might be to the point I have to bring it to a shop that has scan tools that can see injector pulse/cam signals/crank signals and everything else.

[Colbyt93]

So update, I've read a while ago about fuel getting into the dde from a leaky sensor so I figured I'd check and sure enough as soon as I open the box the dde sits in, reaked of diesel, so I took the computer out and it was fairly saturated as well as the harness. I cleaned everything thoroughly with electrical cleaner and a light scrubbing with super soft brush, as well as cleaned up the wire harness/connectors the best I could, then started to search for a leaky sensor and sure enough the fuel temp sensor just before the hpfp was soaked inside the plug, so with that on its way and the dde all dried/installed I'll give an update once the new fuel temp sensor is installed, hoping this is the cause of my mystery misfire!

[DialedIn]

I'm glad to hear that you found a fault/the cause of your problems.

[wcs531]

Seems the diesel wicking up to the DDE is becoming less rare.

Is it part# 13537789304? I was having trouble finding it on realoem, and for some reason they list it as the 335d only. I'll have to check mine out and maybe even just replace it preemptively.

[Colbyt93]

I'd imagine it's more rare because it's been fixed in most of the vehicles that are still on the road and I ordered mine from fcp euro part #13537806960, you can pull the plug and look inside to see if it's dry but doing so without removing the intake would be a pain

[wcs531]

Originally Posted by Colbyt93

I'd imagine it's more rare because it's been fixed in most of the vehicles that are still on the road and I ordered mine from fcp euro part #13537806960, you can pull the plug and look inside to see if it's dry but doing so without removing the intake would be a pain

Ah so the sensor is integrated into the line, thank you