[MegaMatt3]

My car has begun to stall on cold starts. This doesn't happen every time, but often enough where I began recording each cold start until I captured it. There are two videos in the Imgur below, taken 2 days in a row. One is worse than the other, nearly stalling completely.

I'm not touching the accelerator at all during these videos - the car is overcompensating for the near stalls by winding up the engine, I think.

This is 2016 M235i with NO modifications to my car at all. All stock.

What could this be?

View post on imgur.com

View post on imgur.com

[MegaMatt3]

Bumping this. Anybody have any thoughts?

[trilax59]

Maybe try unplugging your MAF sensor. I had that after installing my intake and unplugging and replugging it back in seemed to do the trick.

[MegaMatt3]

Thanks for the tip. Funny you should mention MAF sensor. I've been having an issue since about 1500 miles on the car where it'll sometimes shudder and /or lurch when I give it gas or let off the throttle. It's usually subtle (I feel it, but others cannot), but sometimes it's fairly violent. Seems more noticeable in extreme temperatures, maybe more so hot than cold. Maybe a bad MAF sensor? Can those be replaced?

[overcoil]

mass air flow sensor failure is common and easy to either replace or check the connection, usually sets off a check engine light and can mess with transmission shifting.

Could be anything from a a bad sensor to a bad fuel pump.

[MegaMatt3]

No check engine lights, unfortunately, for all 70k miles it's been driven. My local non-dealership shop was started by ex-BMW dealerships techs. You think if I ask them to test the MAF sensor and fuel pump, they'll know what to do? Any specific direction I should give them?

[MegaMatt3]

By the way, this is a manual, in case that's relevant.

[trilax59]

I would suggest bringing it to a dealership or Indy shop and get their professional opinion. They will definitely understand the issue and will likely be able to come up with a solution.

[jyerelek]

I had the exact same problem on my 435i and took it into the dealer. They reset the vehicles software which lost all the things I coded but also fixed the problem. I've re coded now and issue hasn't come back.

[arhoads335i]

Kinda sounds like a HPFP

[RMNB]

Originally Posted by MegaMatt3

No check engine lights, unfortunately, for all 70k miles it's been driven. My local non-dealership shop was started by ex-BMW dealerships techs. You think if I ask them to test the MAF sensor and fuel pump, they'll know what to do? Any specific direction I should give them?

Once they read the codes your problem will be fixed. Either an air flow issue or simply fuel flow issue. Who is your local tech??

[MegaMatt3]

@arhoads335i Apologize for the ignorance, but what is HPFP?

335xi Beast I did speak with my local shop and the guy said there could be codes stored from this happening, even if the check engine light never came on. So I guess there's history there when they plug it up and read codes? My shop is a small local one called Revolution Motor Works, here in Maryland. Started by two former BMW techs. Only been going for about a year, but they've been helpful. The guy I spoke with yesterday had to "check on that" several times with my questions, where he'd put me on hold and ask someone else, so that wasn't great. But otherwise it's been ok. They said they'd want me to leave the car overnight so they could do a cold start in the morning while it's hooked up. I think that's a fine plan, but it's only happening maybe one out of every 7-10 starts, so I'm not sure they'll get what they need.

Of course, I can put up with some weird cold starts. But if this problem is related to the driving problem I've had for 68,000 miles where the car doesn't seem to receive and give back throttle very cleanly, sometimes lurching or shuddering, now I'm very interested.

[RMNB]

Originally Posted by MegaMatt3

@arhoads335i Apologize for the ignorance, but what is HPFP?

335xi Beast I did speak with my local shop and the guy said there could be codes stored from this happening, even if the check engine light never came on. So I guess there's history there when they plug it up and read codes? My shop is a small local one called Revolution Motor Works, here in Maryland. Started by two former BMW techs. Only been going for about a year, but they've been helpful. The guy I spoke with yesterday had to "check on that" several times with my questions, where he'd put me on hold and ask someone else, so that wasn't great. But otherwise it's been ok. They said they'd want me to leave the car overnight so they could do a cold start in the morning while it's hooked up. I think that's a fine plan, but it's only happening maybe one out of every 7-10 starts, so I'm not sure they'll get what they need.

Of course, I can put up with some weird cold starts. But if this problem is related to the driving problem I've had for 68,000 miles where the car doesn't seem to receive and give back throttle very cleanly, sometimes lurching or shuddering, now I'm very interested.

High Pressure Fuel Pump (HPFP). Keep us posted on what your tech finds wrong with your car. My tech at AKTIV-Gaithersburg just replaced my wife's HPFP on her 550xi but that's a known problem on these cars. Let us know … curious to see how it works out.

[MegaMatt3]

@335xi Beast Thanks. I'll definitely bring that up to my shop. What symptoms was your wife initially experiencing? And how did they figure out the HPFP was the cause?

[RMNB]

Originally Posted by MegaMatt3

@335xi Beast Thanks. I'll definitely bring that up to my shop. What symptoms was your wife initially experiencing? And how did they figure out the HPFP was the cause?

Symptoms were similar to a heart attack...chest pain, shortness of breath just wasn't feeling right. Sorry I just had to.

The car was never smooth at idle...almost surged at times, then almost stalls. Then the Drive Train Malfunction light comes on. Car shakes with half power, almost limp mode kinda. But we all know the HPFP, Injectors, O2 sensors on the "Hit" list on the service bulletin for the extended warranty fix for free by BMW. She's fixed and runs fine at the moment...hold your breath.

What's the latest on yours?

[RocketF22]

it sounds a lot like what happened to my Audi s4 a few years back. I hope its not but if it is maybe I can save u some money. tow it to your mechanic. your engine may be ready to blow or did blow but hasnt thrown a rod. check it out fast. dont make my mistake. I drove mine and started mine a lot until the guys at Audi told me what was up

[MegaMatt3]

@335xi Beast Thanks for the extra info. Can you elaborate on your statement: "But we all know the HPFP, Injectors, O2 sensors on the "Hit" list on the service bulletin for the extended warranty fix for free by BMW."

I'm planning on taking it to them next week and leaving it overnight so they can do a cold start in the morning with it plugged up. I'm a little concerned that I haven't had any lights at all. Makes me think they're going to come up empty on the diagnostics.

Apparently there's also a LPFP. In 3rd grader terms, what's the difference between HPFP and LPFP? Seems to me low pressure would be at idle, but I genuinely know nothing.

[K8_M235i]

My car does this when the weather changes. Usually the first very hot day in awhile. A few cold starts later it doesn't do it.

[overcoil]

Originally Posted by K8_M235i

My car does this when the weather changes. Usually the first very hot day in awhile. A few cold starts later it doesn't do it.

Isn’t fuel formulated for cold weather ( or warm weather )

https://www.caranddriver.com/news/a1...ine-explained/

Wonder if that is the culprit

[MegaMatt3]

Well, I'll say that the cold start issue didn't occur on days of extreme temperature. This was about a month ago when the days were a little warmer, but it was the morning, and I'm parked in a garage when I start. The temperatures wouldn't have been too high (or low).

ScottSinger If it were only the cold start issue, I might chalk it up to what others have proposed in other threads, like a bad batch of gas or even deposits left over time (the car has 70k miles). But I'm also having that power delivery issue when I give and let off the throttle. It's not severe, but noticeable pretty much all the time, and that's been going on for at least 60k miles. That wouldn't just be bad gas, and more and more I'm thinking it's either an air delivery issue or a fuel delivery issue.

My concern is that the car won't have thrown any codes at all, and the techs are going to throw their hands up. That's what happened at the dealership when it was under warranty and I repeatedly got nowhere on the throttle issue. Cold start issue is new, so maybe a code will be there, but I'm not optimistic given the history.

[nixeighty6]

My car does this on cold starts but only if I put it in drive right after starting. I just caulked it up to load on the engine to soon after starting cold, when the ignition is advanced. My cars a 14 m235i automatic with 33k miles, I'll do plugs in a week or so with a stage 2 and will let you know.
did plugs today when i was bored.. i'll update if it fixed it

[MegaMatt3]

Ok thanks. Mine's a manual, btw, so I'm just throwing it in neutral after starting.