Ignition missfire....possibly?

BimmerBrian440 · 05-25-2024, 12:53 AM

Hey guys, new to the site.

Second owner of an Estoril Blue, 2017 440i Gran Coupe XDrive that I picked up back in the summer of 2021. Been a great car. Has the 355hp MPPSK package as well as the MSport 1 & 2 package (adaptive suspension, big brakes, etc). Love this car. Good power, sharp handling, practical, great mileage, plenty of storage. Car is stock, with the exception of a paint matched rear spoiler and the recent addition of a set of a set of bronzed and staggered VMR V703's (19x8.5" 245/40R19 and 19x9.5" 275/35R19's). Will get some pics up when I finish setting up the account.

My issue is, the mileage is getting up there 155,000km and with that, some wear items are needing replacing.

Car has treated me really well for the most part. As part of preventative maintenance, I changed all of the fluids (coolant, front and rear diffs, transfer case, transmission) this spring and to my surprise, it seems as though all but the front differential had been done at least once, by the previous owner.

My most recent issue has been chasing down a stumble and miss problem. Starts and idles smooth. Has this weird little "shudder" for 2-3 seconds after the first 45 seconds or so, of running, but I just attributed it to the ECU switching maps as the car warmed up? Otherwise, idles smooth as glass with the very odd, random miss. Nothing I could pinpoint. The drama happens when I start driving. Mostly at light throttle I can feel a slight miss, but even as I roll more aggressively into the throttle like you would when say passing a car, I would get what I could only describe as a stumble or random surging of power? It also intermittently "falls on its face" between up-shift gear changes under light/moderate pedal, from time to time. Unfortunately, whatever it is, isn't severe enough to set off a check engine light. I went ahead and bought the full version of BimmerLink, and have found and cleared other random unrelated codes, bur nothing pertaining to the issue I'm having? Haven't quite figured out how to datalog with it yet, or what parameter I should be datalogging, so if there are any of you in here that are well versed with the software, please feel free to chime in.

I did some research and changed a few common wear parts I though should be done at this mileage anyway. Changed all of the spart plugs, that to be honest....looked pretty good. Changed both Vanos actuators, (that based on my research tend to fail over time) and while it did smooth out some of my issue I was having during cold operation and cruise...I am still having the problem. My next guess was ignition coils (that from what I can tell seem to be original), but before I threw any more money at it, I thought I'd see if anyone had any ideas? I haven't ruled out O2 sensors, but again....no check engine light, or codes tripped.

Thoughts?

pauli18c · 05-30-2024, 08:35 AM

I just had this issue on my 340i.

Had the stumbles on start up, and it was noticable while driving on the highway while on cruise.

Progressively got worse for a few months.
No codes.

I logged the intake and exhaust VANOS with MHD and saw the exhaust VANOS jumping around some, actual vs required. So I replaced both of them. Didn't do anything really.

Then I finally got a code for my O2 sensor. I then logged my AFR actual vs required and saw it was going crazy jumping all over the place. Replaced the O2 sensor and bam, everything back to perfect again, driving like normal.

I would definitely log your AFR and see if it's jumping all over the place.

I've now had to replace both O2 sensors with 87k on it. Post cat at 65k, and pre cat at 87k miles

g340ix · 05-30-2024, 08:55 AM

Quote:

Originally Posted by pauli18c

I just had this issue on my 340i.

Had the stumbles on start up, and it was noticable while driving on the highway while on cruise.

Progressively got worse for a few months.
No codes.

I logged the intake and exhaust VANOS with MHD and saw the exhaust VANOS jumping around some, actual vs required. So I replaced both of them. Didn't do anything really.

Then I finally got a code for my O2 sensor. I then logged my AFR actual vs required and saw it was going crazy jumping all over the place. Replaced the O2 sensor and bam, everything back to perfect again, driving like normal.

I would definitely log your AFR and see if it's jumping all over the place.

I've now had to replace both O2 sensors with 87k on it. Post cat at 65k, and pre cat at 87k miles

any chance you can post your log after you replaced the actuators?

pauli18c · 05-30-2024, 01:01 PM

Quote:

Originally Posted by g340ix

any chance you can post your log after you replaced the actuators?

I didn't record a log after as it didn't do anything for me, what exactly are you looking to see?

They should be relatively the same lines overlapping each other if they're working correctly

g340ix · 05-31-2024, 08:44 AM

Quote:

Originally Posted by pauli18c

I didn't record a log after as it didn't do anything for me, what exactly are you looking to see?

They should be relatively the same lines overlapping each other if they're working correctly

my exhaust vanos is driving me nuts, I've replaced the solenoid a few times, I have a feeling I may need to replace the central valve

pauli18c · 05-31-2024, 11:41 AM

Quote:

Originally Posted by g340ix

my exhaust vanos is driving me nuts, I've replaced the solenoid a few times, I have a feeling I may need to replace the central valve

What's making you think it's bad?

This was the log that made me think mine were bad:

samspiderman3125 · 06-03-2024, 09:03 AM

Quote:

Originally Posted by pauli18c

What's making you think it's bad?

This was the log that made me think mine were bad:

What parameters are you looking for to determine correct VANOS operation? Dont see it talked about here much

g340ix · 06-03-2024, 09:36 AM

Quote:

Originally Posted by pauli18c

What's making you think it's bad?

This was the log that made me think mine were bad:

Here is mine, one is very light throttle, doesn't look horrible, but during spool up and mid range under WOT it is atrocious

BimmerBrian440 · 06-03-2024, 10:39 PM

Well, update time. Ironically, about 2-days after I made this post, I finally got a check engine light from the pre cat 02 sensor (as I and it seems Pauli suspected). Priced out the BMW one and said f*ck that. Bought a Bosch 17404 sensor instead for under $100 CAD to my door. When I pulled the airbox off to change the sensor, I decided I might as well clean it up and saw it was 1/4 full of dirt and sand and that my filter was nearly plugged solid. So...a new 02 sensor and a $20 Mann air filter and the car runs like new again. Feels like I picked up about 30hp too. lol

Thanks to all that responded.

05-25-2024, 12:53 AM	#1
BimmerBrian440 Registered 0 Rep 2 Posts Drives: 2017 F36 440i Join Date: May 2024 Location: Waterloo, ON iTrader: (0)	Ignition missfire....possibly? Hey guys, new to the site. Second owner of an Estoril Blue, 2017 440i Gran Coupe XDrive that I picked up back in the summer of 2021. Been a great car. Has the 355hp MPPSK package as well as the MSport 1 & 2 package (adaptive suspension, big brakes, etc). Love this car. Good power, sharp handling, practical, great mileage, plenty of storage. Car is stock, with the exception of a paint matched rear spoiler and the recent addition of a set of a set of bronzed and staggered VMR V703's (19x8.5" 245/40R19 and 19x9.5" 275/35R19's). Will get some pics up when I finish setting up the account. My issue is, the mileage is getting up there 155,000km and with that, some wear items are needing replacing. Car has treated me really well for the most part. As part of preventative maintenance, I changed all of the fluids (coolant, front and rear diffs, transfer case, transmission) this spring and to my surprise, it seems as though all but the front differential had been done at least once, by the previous owner. My most recent issue has been chasing down a stumble and miss problem. Starts and idles smooth. Has this weird little "shudder" for 2-3 seconds after the first 45 seconds or so, of running, but I just attributed it to the ECU switching maps as the car warmed up? Otherwise, idles smooth as glass with the very odd, random miss. Nothing I could pinpoint. The drama happens when I start driving. Mostly at light throttle I can feel a slight miss, but even as I roll more aggressively into the throttle like you would when say passing a car, I would get what I could only describe as a stumble or random surging of power? It also intermittently "falls on its face" between up-shift gear changes under light/moderate pedal, from time to time. Unfortunately, whatever it is, isn't severe enough to set off a check engine light. I went ahead and bought the full version of BimmerLink, and have found and cleared other random unrelated codes, bur nothing pertaining to the issue I'm having? Haven't quite figured out how to datalog with it yet, or what parameter I should be datalogging, so if there are any of you in here that are well versed with the software, please feel free to chime in. I did some research and changed a few common wear parts I though should be done at this mileage anyway. Changed all of the spart plugs, that to be honest....looked pretty good. Changed both Vanos actuators, (that based on my research tend to fail over time) and while it did smooth out some of my issue I was having during cold operation and cruise...I am still having the problem. My next guess was ignition coils (that from what I can tell seem to be original), but before I threw any more money at it, I thought I'd see if anyone had any ideas? I haven't ruled out O2 sensors, but again....no check engine light, or codes tripped. Thoughts?
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05-30-2024, 08:35 AM	#2
pauli18c Lieutenant 215 Rep 526 Posts Drives: 2017 340i RWD M Sport Join Date: Jun 2019 Location: Chicago iTrader: (4)	I just had this issue on my 340i. Had the stumbles on start up, and it was noticable while driving on the highway while on cruise. Progressively got worse for a few months. No codes. I logged the intake and exhaust VANOS with MHD and saw the exhaust VANOS jumping around some, actual vs required. So I replaced both of them. Didn't do anything really. Then I finally got a code for my O2 sensor. I then logged my AFR actual vs required and saw it was going crazy jumping all over the place. Replaced the O2 sensor and bam, everything back to perfect again, driving like normal. I would definitely log your AFR and see if it's jumping all over the place. I've now had to replace both O2 sensors with 87k on it. Post cat at 65k, and pre cat at 87k miles __________________ 2017 340i M Sport Alpine White / Coral Dorch Stg2, CTS catless, xHP, Custom E50 Tuned by Shoup
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06-03-2024, 10:39 PM	#9
BimmerBrian440 Registered 0 Rep 2 Posts Drives: 2017 F36 440i Join Date: May 2024 Location: Waterloo, ON iTrader: (0)	Well, update time. Ironically, about 2-days after I made this post, I finally got a check engine light from the pre cat 02 sensor (as I and it seems Pauli suspected). Priced out the BMW one and said f*ck that. Bought a Bosch 17404 sensor instead for under $100 CAD to my door. When I pulled the airbox off to change the sensor, I decided I might as well clean it up and saw it was 1/4 full of dirt and sand and that my filter was nearly plugged solid. So...a new 02 sensor and a $20 Mann air filter and the car runs like new again. Feels like I picked up about 30hp too. lol Thanks to all that responded.
	Appreciate 0 Quote