[rhmarquez]

Hi! New to the forums here. The N55 in my 2014 435i starts misfiring and shaking a little bit upon startup, doesn't matter if its a cold start or if car is already warm. Weird thing is that it's an intermittent issue and happens randomly. I already tried running Techron Fuel System cleaner, cleaned MAF/MAP sensors, installed fresh OE Spark Plugs and Coils to no avail. As soon as the RPM starts coming down like 30-45 secs after engine start, the rough idle seems to disappear every time. While driving everything feels fine.

Although I'm not getting a Check Engine light. I pulled the codes using Bimmerlink, and this is what I got. Any tips?

*Also, I don't get those "Check Control Message: Refill Engine Oil", I just did an oil change, and in iDrive it shows the level as full.

[jh_f30]

Originally Posted by rhmarquez

Hi! New to the forums here. The N55 in my 2014 435i starts misfiring and shaking a little bit upon startup, doesn't matter if its a cold start or if car is already warm. Weird thing is that it's an intermittent issue and happens randomly. I already tried running Techron Fuel System cleaner, cleaned MAF/MAP sensors, installed fresh OE Spark Plugs and Coils to no avail. As soon as the RPM starts coming down like 30-45 secs after engine start, the rough idle seems to disappear every time. While driving everything feels fine.

Although I'm not getting a Check Engine light. I pulled the codes using Bimmerlink, and this is what I got. Any tips?

*Also, I don't get those "Check Control Message: Refill Engine Oil", I just did an oil change, and in iDrive it shows the level as full.

Check your battery voltage. I've heard when a battery gets weak, the car throws all sorts of random codes.

BimmerLink has a battery voltage value available.

[rhmarquez]

Originally Posted by jh_f30

Check your battery voltage. I've heard when a battery gets weak, the car throws all sorts of random codes.

BimmerLink has a battery voltage value available.

I'll definitely check that tomorrow. Although I think a bit unlikely, due to the fact that the engine cranks normally with no hesitation at all. But I'll report tomorrow.

[awilki0101]

Originally Posted by rhmarquez

I'll definitely check that tomorrow. Although I think a bit unlikely, due to the fact that the engine cranks normally with no hesitation at all. But I'll report tomorrow.

Still very likely battery. All of those codes too random. Even with lower voltage the battery will have enough to crank car but will still throw codes. With age of car I wouldn't be surprised if battery never changed and would be right about time to do so

[Zanity]

You missed my post by a few days, see if this helps.:

https://f30.bimmerpost.com/forums/sh....php?t=1727053

[rhmarquez]

Originally Posted by awilki0101

Still very likely battery. All of those codes too random. Even with lower voltage the battery will have enough to crank car but will still throw codes. With age of car I wouldn't be surprised if battery never changed and would be right about time to do so

Ok, just did a little bit of data logging using bimmerlink. My battery has a build date of 52/13, safe to say it's never been replaced (car is a 2014 model).

With ignition ON but engine OFF I was getting 12.15V.

While cranking, the lowest it went down to was: 11.25V

Once the engine was started: 14.8-15.0V

Do all those numbers seem normal?

[awilki0101]

The 11.25 is the giveaway that's too low. When car is running it will use alternator so should always be around 14

[rhmarquez]

Originally Posted by awilki0101

The 11.25 is the giveaway that's too low. When car is running it will use alternator so should always be around 14

Related to my startup misfire issues or not I’ll definitely look into replacing it. If it’s not the cause, it will likely start to cause problems soon anyways since its getting old almost at 7 years now. Bimmerlink shows the battery’s State of Charge as 73%. Is that acceptable, or already bad?

[awilki0101]

Originally Posted by rhmarquez

Related to my startup misfire issues or not I’ll definitely look into replacing it. If it’s not the cause, it will likely start to cause problems soon anyways since its getting old almost at 7 years now. Bimmerlink shows the battery’s State of Charge as 73%. Is that acceptable, or already bad?

That's a bit low. Typically operates 80% or higher. Buy yourself a new battery and get a Foxwell scan tool. They are about $160 but you can clear yours codes with it and register the new battery so no new problems come up. It will cost you about the same to have BMW register the battery and check everything so it's a worthwhile investment

[jh_f30]

Originally Posted by awilki0101

That's a bit low. Typically operates 80% or higher. Buy yourself a new battery and get a Foxwell scan tool. They are about $160 but you can clear yours codes with it and register the new battery so no new problems come up. It will cost you about the same to have BMW register the battery and check everything so it's a worthwhile investment

Bimmerlink can clear codes and register battery as well.

[rhmarquez]

Well, replaced/registered the battery, cleared all the codes and they are still showing up. Worth noting that these codes only appear on the "Info Memory" and not the "Error Memory" or "Permanent Errors". The ones I'm most interested in are the ones from Digital Engine Electronics, since they're likely the cause of the startup misfires/rough idle. I was thinking maybe a bad MAF, MAP sensor, or leaking fuel injector... Does someone have any other ideas?

[rhmarquez]

Ok, so I'm trying to understand these codes in a logical way. Focusing just on the most important codes (I guess). Follow the numbers here with their corresponding codes in the attached image.

1. Apparently there's a leak somewhere. This code from what I've seen relates to the fuel tank vent breather in the engine. So there's vaccum pressure leaking out of somewhere here.
2. Since there's a leak, I'm not getting adequate fuel pressure, which would agree with these codes.
3. Since I'm not getting enough fuel, there's too much air for the amount of fuel.
4. Ultimately causing the engine to misfire, and triggering this code.

Would this make sense? Any pro on the N55 engine, feel free to chime in!

[Rebound]

When I read your first post, the first thing I thought was failed PCV. There are a few YouTube videos if N55 PCV replacement. Take a look at some, particularly the one or two which show the symptoms which the PCV failure leads to.

As for the codes... did you reset/clear all codes and restart the test?

[rhmarquez]

Originally Posted by Rebound

When I read your first post, the first thing I thought was failed PCV. There are a few YouTube videos if N55 PCV replacement. Take a look at some, particularly the one or two which show the symptoms which the PCV failure leads to.

As for the codes... did you reset/clear all codes and restart the test?

Yeah, I've reset them multiple times. I'll check today if it's the PCV system. The weird thing is that all the videos I've seen mention a whining noise, check engine light, or limp mode. And I don't get any of those... Just misfires/rough idles for the first 20-30 seconds the car is on, after that it goes back to normal.

I'm also inspecting today the EVAP system with its fuel breather lines, since I'm getting a code related to it. Also read it may be the NVLD module.. but again, symptoms always have a check engine light. Hopefully is just a cracked fuel breather line that I can DIY and call it a day.

[floridaorange]

So at stop lights while idling - it's not rough? Just 20-30 secs after startup?

[rhmarquez]

Originally Posted by floridaorange

So at stop lights while idling - it's not rough? Just 20-30 secs after startup?

Exactly. It's weird. And it only idles rough sometimes on startup. Sometimes worse than others. Doesn't matter if it's cold or warm start. My friend the other day mentioned "what do you have under there, an american v8 with cams?" And after 30 secs it's normal. I'll post a video if it decides to do it today.

[floridaorange]

Ya that's exactly how my issues began... it got worse after months of trying to diy it. New plugs, coils, battery, tiny exhaust leak fixed.... brought to tuning shop they said the rough idle was normal no way.
I also cleaned my MAF... but BM3 flashing was clearing my codes. At least you are on the right path.

[rhmarquez]

Originally Posted by floridaorange

Ya that's exactly how my issues began... it got worse after months of trying to diy it. New plugs, coils, battery, tiny exhaust leak fixed.... brought to tuning shop they said the rough idle was normal no way.

That's crazy! But it's what I'm starting to believe. Hahaha. Ever since I got her at 62k miles it's had a very small rough idle on start, but I just feel it getting progressively worse.

[Rebound]

Originally Posted by rhmarquez

Yeah, I've reset them multiple times. I'll check today if it's the PCV system. The weird thing is that all the videos I've seen mention a whining noise, check engine light, or limp mode. And I don't get any of those... Just misfires/rough idles for the first 20-30 seconds the car is on, after that it goes back to normal.

I'm also inspecting today the EVAP system with its fuel breather lines, since I'm getting a code related to it. Also read it may be the NVLD module.. but again, symptoms always have a check engine light. Hopefully is just a cracked fuel breather line that I can DIY and call it a day.

Maybe I wasn't clear, but there are videos on YouTube of a bad PCV on an N55. Just listen to what a bad PCV sounds like; that should be all the diagnosis you need.

[rhmarquez]

Originally Posted by Rebound

Maybe I wasn't clear, but there are videos on YouTube of a bad PCV on an N55. Just listen to what a bad PCV sounds like; that should be all the diagnosis you need.

Yeah, I actually looked into it today. I'm not getting most of the symptoms of a bad PCV valve.

Out of 3 different trips I did today, the last startup was the only one with misfires/rough idle. And like always, lasted for the initial 20 seconds after startup and then all good.

Also worth noting that on my first trip today, I had a code saying "CODE 1FB601: AUTO START STOP FUNCTION DISABLED". Reset it, and as soon as I started the engine again, came right up again with all my other usual codes listed above. And just like the code said, the car wasn't auto start-stopping. But then on my second and third trip, it started auto start-stoping normally again.

I'm starting to give up on this, and will probably have to take it to a shop.

[exE36M3]

So... rough idle and you took care of all the electrical and mechanical stuff.
I'm leaning toward a vacuum leak. Like a cracked charge pipe? If you are over 60k miles, might be worth a look.
A LOT of the plastics under the hood of the x35 cars are pretty brittle by 65k.

[rhmarquez]

Originally Posted by exE36M3

So... rough idle and you took care of all the electrical and mechanical stuff.
I'm leaning toward a vacuum leak. Like a cracked charge pipe? If you are over 60k miles, might be worth a look.
A LOT of the plastics under the hood of the x35 cars are pretty brittle by 65k.

I have an AFE Power aluminum charge pipe, but now that you mention it, when I unscrewed my intake manifold for the oil filter housing gasket, the charge pipe felt loose at the bottom (intercooler I believe) connection. And I never got around to take a look at it. I'll definitely check that!

But could this be the cause of my symptoms, since it only happens on startup and my boost seems fine?