MAF Hack and Running Terribly

[LongTallTexan]

So after I did the timing belt service, the 325i was running great. I was patting myself on the back. Then I really jinxed it by offering my my wife a ride Saturday down to Travis lake for a margarita.

Well it started running like crap. Nailing it above 4k rpm it runs great. But under, it sputters and surges.

So I made it home and checked all the electrical connections and it all looks good.

I took it out again today (after unplugging and plugging in the MAF sensor connection) and it still runs like crap. Stopped at a store, unplugged and plugged in the MAF sensor cable again, and it ran great - for about 5 minutes. Then crap again. And it seemed to burn a 1/4 tank of gas!!!!

I had this problem months ago, but not that bad. After a new TPS (the closed throttle switch was broken) and general maintenance, it started running much better.

But now!

So I thought maybe the MAF. But I look at the parts diagram and I see an AFM (barn door) type sensor. But I have a MAF, Bosch #0 280 218 032. Is this a common conversion? The part's inlet flange is cut off.

Is my focus on the MAF warranted? It looks cheap enough to replace. But is there a way to know if I'm barking up the wrong tree?

My fuel injection experience is with K-jet, so any advice here is appreciated.

Thanks much!

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And yes, I'll probably start tearing things apart to check the crank and cam gear timing marks.

[sienayr]

It probably has the Miller MAF conversion, which involves a chip in the DME and installing the MAF. Unfortunately you probably can't tell just by looking if it's a miller conversion, you may have to check the DME for a replacement chip. Or figure out what MAF you need and replace it, you may be able to trace it by part numbers on the MAF and some creative googling.

[LongTallTexan]

It probably has the Miller MAF conversion, which involves a chip in the DME and installing the MAF. Unfortunately you probably can't tell just by looking if it's a miller conversion, you may have to check the DME for a replacement chip. Or figure out what MAF you need and replace it, you may be able to trace it by part numbers on the MAF and some creative googling.

I do know the the previous owner chipped it. And now I recall he did say he upgraded to MAF from the AFM. Figure the part number on the housing is not what I'm looking for but rather the measuring device that is screwed on to it. No hints on that part.

And it has 4 connectors where everything out there I google has 5.

Miller was a vendor that marketed it, or maybe DIY instructions?

I'll contact the PO and ask if he can help.

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[LongTallTexan]

And I need to give it a good cleaning before I panic much more.

[82eye]

could be a ssquid conversion. it converts a generic maf input to a signal the ecu can understand.

edit : works with or without a chip. i'd pull the ecu and look anyway.

[mbonder]

Vacuum leak? Sounds like there's too much air getting into the system (or the metering of that air is incorrect--which would confirm your thoughts). How's the vacuum line that runs from the intake manifold to the fuel pressure regulator? Check for cracks in the intake boot in the folds of the accordion sections. Also check that the rubber hoses to the ICV are not cracked and secured tightly. Clean the sensor in the MAF as well as the connector sections.

[LongTallTexan]

Vacuum leak? Sounds like there's too much air getting into the system (or the metering of that air is incorrect--which would confirm your thoughts). How's the vacuum line that runs from the intake manifold to the fuel pressure regulator? Check for cracks in the intake boot in the folds of the accordion sections. Also check that the rubber hoses to the ICV are not cracked and secured tightly. Clean the sensor in the MAF as well as the connector sections.

I did check that line to the fuel pressure regulator and it is not as snug as I'd like on the intake manifold side. Maybe a tiny zip tie is in its future.

The throttle body fittings to the power brakes are loose.

All other hoses look good.

I cleaned the MAF (did not look like it needed it), and will put it all back together today and see.

If it still runs bad, I'll pull off the TB and address the power brakes (and any other fittings).

I also bought a crank position sensor to tick the "throw parts at it" box.

[LongTallTexan]

After cleaning the MAF sensor and putting it back together, it still ran like crap. BTW the MAF sensor did not look like it needed cleaning.

So I put on the new crank position (speed?) sensor and now it runs great again!!!!!

It was a pain to replace, just doing a timing belt service and having to do most of it again to get to the CPS!

But well worth it!!!!!!

[LongTallTexan]

Threw another part at it, the cam sensor. And new cap, rotor and plugs while I was at it.

Pulled the brain and checked on the chip. It is the Miller chip upgrade for MAF sensor. (I re-wrote the green writing in black.)

I looked at the circuit board and everything looks good. Nothing burned or discolored. All soldering looks good.

This now seems to the regular symptoms when driving a loop with lots of curves and hills.

Drives GREAT!!!! For a few miles. Then on a fairly steep uphill grade running at 3k rpm, the engine starts losing power and "lunging."

Over 4k rpm, with my foot in it, runs fine.

I pull over, shut her down. Disconnect the MAF connector. Plug it back in.

And it runs great again!

Maybe the connection. Maybe the MAF is really going out.

Any thoughts appreciated.
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[Mikealwa]

Just to rule it out could you shine a light in the gas tank, see if you have sediment choking the field pump after a bit of driving? I've heard that hypothesized on a different thread with similar symptoms. I'm not sure if these symptoms would manifest from sediment in the tank, but worth a look. Maybe change the fuel filter if it hasn't been done and you have a bit of extra cash. I may be off track here.

[LongTallTexan]

Just to rule it out could you shine a light in the gas tank, see if you have sediment choking the field pump after a bit of driving? I've heard that hypothesized on a different thread with similar symptoms. I'm not sure if these symptoms would manifest from sediment in the tank, but worth a look. Maybe change the fuel filter if it hasn't been done and you have a bit of extra cash. I may be off track here.

The fuel pump was replaced a year or so ago. I think I replaced the fuel filter a few years ago (but that's cheap and easy to replace and rule out).

[82eye]

maybe reach out to miller and seed if you can source just the maf sensor.

[LongTallTexan]

maybe reach out to miller and seed if you can source just the maf sensor.

Thanks much.

Contacted them yesterday. Giving them some time to reply.

I have a feeling a new MAF is in my future. (Odd that the current one lasted < 10 years.)

[82eye]

Thanks much.

Contacted them yesterday. Giving them some time to reply.

I have a feeling a new MAF is in my future. (Odd that the current one lasted < 10 years.)

it's a generic maf. they should be viewed as a wear item. they don't last like original equipment does. let us know if that solves it, i've seen this pop up before in relation to maf conversions, not just the miller.

[LongTallTexan]

Miller is unresponsive to questions re their contact screen.

And their phone number on their website is out of service.

I am struggling. Any help identifying a new MAF is MUCH appreciated!!!!!!

[82eye]

Miller is unresponsive to questions re their contact screen.

And their phone number on their website is out of service.

I am struggling. Any help identifying a new MAF is MUCH appreciated!!!!!!

see if sssquid has any generic mafs in stock. the connector looks the same. i'm super surprised at miller going dark. guys seem to be going bust or hitting a wall everywhere.

[82eye]

double post. this site is really buggy.

[82eye]

i pulled the part number off the maf you have in the pic and found a half dozen places that have it. try rock auto even.

edit: rock auto and a couple other places list a cheapo generic as well. the bosch is pricey, you might get away with a generic, pay attention to the connector if you do.

[LongTallTexan]

i pulled the part number off the maf you have in the pic and found a half dozen places that have it. try rock auto even.

edit: rock auto and a couple other places list a cheapo generic as well. the bosch is pricey, you might get away with a generic, pay attention to the connector if you do.

I can't find an image of that part number (0 280 218 032) with the same style connector. That has spooked me!

I worry the modified housing is sourced as cheap is possibly and the MAF itself is purchased and dropped in.

[82eye]

I can't find an image of that part number (0 280 218 032) with the same style connector. That has spooked me!

I worry the modified housing is sourced as cheap is possibly and the MAF itself is purchased and dropped in.

you can swap the connector. it's 3 screws usually. it's the maf sensor itself that is the likely fail. if it has at all that is.

edit: the sensor itself is the bosch. i'd order that and go from there. a lot of the pics you see on part sites are generic. that may be what is going on.

[82eye]

if you wanna save some cash go pull one off an early 2000's vw jetta or golf with the 1.8 or 2.0L at a wrecker.

i cross referenced and found the maf. all miller did was hack the mount off one side, and pretty shitty at that as well i see.

edit : i have a daily beater 2001 jetta, i went and checked, it has that exact maf lol.

more edit : maybe only the 1.8. turns out mine is swapped. i have a 2.0L though with no turbo.

[LongTallTexan]

you can swap the connector. it's 3 screws usually. it's the maf sensor itself that is the likely fail. if it has at all that is.

edit: the sensor itself is the bosch. i'd order that and go from there. a lot of the pics you see on part sites are generic. that may be what is going on.

Now I'm confused. The 4 pin male contacts and the sensor's housing are a single part that has two screws to attach it to the "housing tube."

But yes, maybe just buy the part and cross my fingers

[82eye]

Now I'm confused. The 4 pin male contacts and the sensor's housing are a single part that has two screws to attach it to the "housing tube."

But yes, maybe just buy the part and cross my fingers

some of the listings for mafs include the number of pins. poke around and see if anyone shows or lists the number. otherwise i'd swap the connector or at least try.

edit: can always order a cheapo from rock auto for the vw and see if you can swap connectors on that before committing to a more expensive bosch maf.

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these guys have a list of vw that use the maf

Mass Air Flow Sensor (New) Bosch 0280218032 (eeuroparts.com)

[LongTallTexan]

Maybe the photos are stock and not accurate. You can see the unit I am holding has a different connector. Can't see if it is a 4 pin connector unfortunately. The top one is $70 on Amazon and I bet has a great return policy! Claims to be Bosch.
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[82eye]

Maybe the photos are stock and not accurate. You can see the unit I am holding has a different connector. Can't see if it is a 4 pin connector unfortunately.
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yeah, none of the part pics show the pins when i look for that maf. some others do. i'm pretty sure it's either the same, works the same, or can be swapped. miller either had to source a part that works off the shelf, or one that converts cheap. probably the first to make even more profit. even if not, you still have all the parts needed.