[flanmorrison]

X

[XutvJet]

First things first, get rid of the oiled air filter. K&N and Dinan intakes use oiled filters and they sometimes don't mesh well with the BMW MAF sensor readings. Install the stock intake and install an OEM style paper filter.

MAF sensors rarely go bad on these cars. It usually the wonky air intake readings from the high flow filters that trip them up. You need to give the car some time, a number of starts, and miles before codes will clear. Typically a couple days and 10+ start/stops.

If you have a major vacuum leak with unmetered air getting in, the motor will run poorly and a CEL typically thrown. Most leaks occur at the charge pipe and only under boost. This isn't a vacuum leak and typically the sound you'll hear is a whistle or whooshing sound as boost pressure leaks out. Rarely will a CEL be thrown as no unmetered is getting in.

What does happen though is that the wastegate works overtime to make up for the loss in boost pressure. If the motor isn't making the commanded boost or the DME is seeing excessive high wastegate duty cycles, then a CEL might be thrown.

Yes, the shop sounds extremely sketchy. I would do my business elsewhere.

I'm an environmental consultant and do a lot of work in Texas, the US, and internationally. Yes, intentional and willful dumping of fuel, or most any chemical for that matter, into the environment is very much against the law and the state of Texas takes this very seriously. Given the shop's response to you, my guess is that they willfully dump petroleum products into their lot on a regular basis. If you care about the water your drink and the ecosystem, then you can report what you saw to the Texas Commission on Environmental Quality (TCEQ) 800-832-8224. Your call can be anonymous and the TCEQ will definitely investigate within 2 days or less.

[Jelly_Belly]

^ Jet nailed this one down.

Get out of there and report them for dumping diesel down the drain. What the fk is wrong with them? I try my best to avoid Chain/Franchise mechanics. Find an independent specialist in your area. Even if labour comes out of your pocket, at least the parts are covered. Unfortunately it sounds like the clock is ticking for you. Get it solved asap before your warranty runs out. Best of luck!

[flanmorrison]

Originally Posted by XutvJet

First things first, get rid of the oiled air filter. K&N and Dinan intakes use oiled filters and they sometimes don't mesh well with the BMW MAF sensor readings. Install the stock intake and install an OEM style paper filter.

MAF sensors rarely go bad on these cars. It usually the wonky air intake readings from the high flow filters that trip them up. You need to give the car some time, a number of starts, and miles before codes will clear. Typically a couple days and 10+ start/stops.

Just to confirm, you believe the MAF High Air Mass reading is due to the Dinan filter? Do you think it will learn the higher volume of air eventually? I find it odd that Dinan_Engineering uses a filter that causes issues with the MAF sensor, and even if it was due to the oil on the filter, I wouldn't think that it'd gunk it up in 24 hours.

Is there any implication to keeping it as-is, besides the potential effects of oil on the MAF? Does a higher volume of air cause any increased stress or wear downstream? If so, would tuning it to adjust for the higher air flow resolve that?

It's worth noting that the first time I brought it in for this issue I was noticing rough idle and the vehicle stalled twice at idle.

Originally Posted by XutvJet

If you have a major vacuum leak with unmetered air getting in, the motor will run poorly and a CEL typically thrown. Most leaks occur at the charge pipe and only under boost. This isn't a vacuum leak and typically the sound you'll hear is a whistle or whooshing sound as boost pressure leaks out. Rarely will a CEL be thrown as no unmetered is getting in.

What does happen though is that the wastegate works overtime to make up for the loss in boost pressure. If the motor isn't making the commanded boost or the DME is seeing excessive high wastegate duty cycles, then a CEL might be thrown.

So what is sounds like you're saying is that the code I'm seeing can only be caused by:
a) a faulty or damaged MAF sensor
b) a large leak before the MAF sensor

Since two MAF sensors have reported the error concurrently, it's likely not the sensor itself.

And since it isn't running like shit, it's probably not a large leak before the MAF sensor.

Leaving the high-flow air filters as the culprit?

Originally Posted by XutvJet

Yes, the shop sounds extremely sketchy. I would do my business elsewhere.

I'm an environmental consultant and do a lot of work in Texas, the US, and internationally. Yes, intentional and willful dumping of fuel, or most any chemical for that matter, into the environment is very much against the law and the state of Texas takes this very seriously. Given the shop's response to you, my guess is that they willfully dump petroleum products into their lot on a regular basis. If you care about the water your drink and the ecosystem, then you can report what you saw to the Texas Commission on Environmental Quality (TCEQ) 800-832-8224. Your call can be anonymous and the TCEQ will definitely investigate within 2 days or less.

Agreed (and oddly coincidental that you are an environmental consultant). I reported to 311, but I might also report to TCEQ tomorrow. It was a very negligent thing to see and I didn't fully absorb it until I got home.

[dradernh]

Originally Posted by Jelly_Belly

Find an independent specialist in your area.

BIMRS.org shows three shops in and around Austin: https://www.bimrs.org/find-a-shop.html.

[John in VA]

Terry Sayther's shop would be a good choice in Austin - long-time BMW tech & straight shooter. https://www.terrysaytherauto.com/

[flanmorrison]

Originally Posted by John in VA

Terry Sayther's shop would be a good choice in Austin - long-time BMW tech & straight shooter. https://www.terrysaytherauto.com/

Thanks. I went to Terry Sayther's shop for a few years, and my wife still goes there. I had a few bad experiences there and it seemed like things were going in the wrong direction, and I just recently rejoined the BMW club. The only reason I used this regional shop was because they are covered under the warranty.

I think I'll be checking out Black Forest or VanosLab for the long-term, I've heard some great things about both.

[RGM330i]

I agree with what everyone has contributed. I especially agree with the oiled air filters issue. As an aside, I had put a CAI with a dry filter that worked with the airbox on a 2018 330i and a couple hundred miles of running developed an engine code. Took it to the dealer....smoke tested and found a pinhole leak in the tube just after the MAF location. Went back to stock with no further issues.

[XutvJet]

Originally Posted by flanmorrison

Just to confirm, you believe the MAF High Air Mass reading is due to the Dinan filter? Do you think it will learn the higher volume of air eventually? I find it odd that Dinan_Engineering uses a filter that causes issues with the MAF sensor, and even if it was due to the oil on the filter, I wouldn't think that it'd gunk it up in 24 hours.

Is there any implication to keeping it as-is, besides the potential effects of oil on the MAF? Does a higher volume of air cause any increased stress or wear downstream? If so, would tuning it to adjust for the higher air flow resolve that?

It's worth noting that the first time I brought it in for this issue I was noticing rough idle and the vehicle stalled twice at idle.



So what is sounds like you're saying is that the code I'm seeing can only be caused by:
a) a faulty or damaged MAF sensor
b) a large leak before the MAF sensor

Since two MAF sensors have reported the error concurrently, it's likely not the sensor itself.

And since it isn't running like shit, it's probably not a large leak before the MAF sensor.

Leaving the high-flow air filters as the culprit?

Yes, Dinan intakes have been known to cause MAF and driveability issues on stock M235s. There is no obvious reason why some cars are affected and others are not.

It makes no sense to me that a MAF sensor would go bad, especially twice. MAF sensors failures in there cars rarely fail (been on this forum since 2015). If there is a MAF issue, it's usually caused by some aftermarket intake/filter. If the MAF sensor is dirty, a few shots of electronics cleaner is all it takes.

Stalling and rough idling isn't normal and isn't caused by a failing MAF. It does sound like you have a vacuum leak somewhere. I'd make sure the MAF is seated correctly in the housing, in intake tubing is fully seated in the accordion connection that leads to the turbo, and verify that the charge pipe isn't cracked at the throttle body connection (I'm assuming your car has the stock, failure prone charge pipe). If that's not it, then a smoke test is needed. It's possible that valve cover could be leaking (rare).

[John in VA]

Originally Posted by flanmorrison

Thanks. I went to Terry Sayther's shop for a few years, and my wife still goes there. I had a few bad experiences there and it seemed like things were going in the wrong direction, and I just recently rejoined the BMW club. The only reason I used this regional shop was because they are covered under the warranty.

That's sad to hear. I hope you spoke with him about your issues.

[flanmorrison]

Originally Posted by XutvJet

I'd make sure the MAF is seated correctly in the housing, in intake tubing is fully seated in the accordion connection that leads to the turbo, and verify that the charge pipe isn't cracked at the throttle body connection (I'm assuming your car has the stock, failure prone charge pipe). If that's not it, then a smoke test is needed. It's possible that valve cover could be leaking (rare).

Yeah, haven't noticed issues under load, only when starting/idling/slowing to idle from 10-15mph in higher RPMs

I visually inspected pipe and c-clamp at the throttle body connection, but I can't get a visual on the connections to the intercooler. Charge pipe is upgraded VRSF. (VRSF intercooler and downpipe are the only two aftermarket parts).

Taking it into BMW tomorrow, I'll ask them to do a smoke test if they can't find anything through disassembly/visual inspection.

Dinan asked me to measure the opening for the MAF sensor, so I guess they're thinking it was a defect or incorrect part.

If it's simply getting too much airflow, can I adjust via tune? That was going to be my next upgrade anyway.