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      12-12-2009, 12:23 PM   #1
E92westy
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Question Disconnected MAF - Car runs better (320i)!

OK, I posted about my 320i 'missing' issue in the sticky thread above.
Had the software update, seemed a bit better but symptoms still present.
Out of curiosity today, I disconnected the MAF and went for a drive.
Viola!! No 'missing', stable idle etc and car went well, if a little 'flat'.
I'm assuming that a new MAF should solve my 'issues'.

It's booked in at the dealer on Thursday, soooo... do I tell them what I've done.. or will they not like the fact I've done this whilst the car's still under warranty?

Will it hurt to run with the MAF disconnected for more than a 'test drive' - there's no light on the dash.

Cheers,

Westy.
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      12-12-2009, 02:30 PM   #2
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The diags will tell them that there is an implausible signal from the MAF. The ECU will revert to using calculated value estimates based on things like throttle position and absolute pressure etc..

If the issue is eliminated by removing the MAF inputs it "suggests" as though this is the root cause to your problem. Long term though using calculated values will cause the car to run either too rich, or too lean and effect both performance and economy.

Oh... I just read its under warranty... I'd connect it back up. The fault code will still remain that the signal went implausible along with freeze frame data of date and mileage. That will probably be enough to point them in the right general direction..
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      12-12-2009, 05:34 PM   #3
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I wouldn't say anything to the stealer.

Certainly disconnecting the MAF on a poor performing diesel and getting restored performance is an indicator of a borked MAF - so I can only assume it'd be the same on this petrol car.

The workshop should be able to sort it fairly easily as quattro says.
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      12-13-2009, 11:05 AM   #4
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it will put the MIL engine management light on eventually, it will be going through drive cycles before it puts it on.....
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      12-13-2009, 12:18 PM   #5
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Thanks guys.
Light has now come on and I've connected it back up.
Let's see what the dealer says later in the week...
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      12-15-2009, 04:55 PM   #6
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Don't want to sound dumb here... what's the MAF??
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      12-15-2009, 05:13 PM   #7
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Mass Airflow Sensor - basically 'senses' the mass of air flowing into the engine.

For more info http://en.wikipedia.org/wiki/Mass_flow_sensor
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      12-15-2009, 05:15 PM   #8
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Mass Airflow Sensor.
Sits in the air intake after the filter.
Had one go flakey on a previous Golf GTI turbo, too
No. 7 on here 'Hot film air mass meter'...



They can get dirty and / or fail without any errors logged.
Lots of info avaliable on a search.
Cheers.
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      12-16-2009, 03:38 PM   #9
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Thanks guys! Here's the next question. On idling a few nights ago someone commented on my engine making a strange noise every so often for about 3 seconds at a time, when I popped the bonnet the sound seemed to be coming from around that MAF area on the engine map above. I had noticed my car not quite driving as good, so I took it for a rag and it's slightly better with no strange noise in idling - any ideas?

The only way I can describe the noise was like white noise from an old TV - but I guess it could be air leaking/gushing/being sucked in?
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      12-16-2009, 05:50 PM   #10
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Can't really say from your description - not noticed that.
All I can say is, if you suspect it, disconnect it and go for a couple of drives.
If it's worse, connect it back up and forget it, if it's better, connect it back up and send it in....

Cheers,

Westy.
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      08-14-2015, 03:27 PM   #11
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Okay I have a 330i 06 I recently bought and intake so I had to remove my maf sensor so after installing the intake I notice there was no space or fitting for my maf sensor I started the car up and it sounded fine but when I stepped on the brake it would idle up and down like if it had a vacuum leak but after letting it run for 5 minutes the car went back to normal I just wana know will it damage anything if I run it without the maf sensor
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      08-14-2015, 07:58 PM   #12
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i've installed a racing tuner chip , car's about 200 bhp now , pick ups much better and no missing at all now , might be worth a try

i've got a sports filter and a sports exhaust aswell .


Quote:
Originally Posted by E92westy View Post
OK, I posted about my 320i 'missing' issue in the sticky thread above.
Had the software update, seemed a bit better but symptoms still present.
Out of curiosity today, I disconnected the MAF and went for a drive.
Viola!! No 'missing', stable idle etc and car went well, if a little 'flat'.
I'm assuming that a new MAF should solve my 'issues'.

It's booked in at the dealer on Thursday, soooo... do I tell them what I've done.. or will they not like the fact I've done this whilst the car's still under warranty?

Will it hurt to run with the MAF disconnected for more than a 'test drive' - there's no light on the dash.

Cheers,

Westy.
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      08-14-2015, 08:00 PM   #13
blood_Game18
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you should connect the sensor as the cars going to jerk a lot , i connected the sensor in mine after a week , runs much better and smooth you need to take out the sensor module from the stock air filter unit

Quote:
Originally Posted by 330ijose View Post
Okay I have a 330i 06 I recently bought and intake so I had to remove my maf sensor so after installing the intake I notice there was no space or fitting for my maf sensor I started the car up and it sounded fine but when I stepped on the brake it would idle up and down like if it had a vacuum leak but after letting it run for 5 minutes the car went back to normal I just wana know will it damage anything if I run it without the maf sensor
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      08-15-2015, 01:28 PM   #14
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The MAF is the ECU's primary load input, from which it bases all calculations for fuelling/timing etc.

Without the MAF the ECU will revert to a safety backup programming, with the aim of allowing the engine to run as best as possible given the situation. You'll almost certainly have poorer fuel economy, less power and worse drivability without the MAF connected, and all of that will without doubt eclipse any small gains your intake might have given you.
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      05-26-2016, 05:43 PM   #15
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unplugged maf

hey guys, its my first post, bought my first BMW sport edition plus privately a few months ago now.
Gorgeous car to look at, full leather all singing all dancing but was a total embarrassment to drive, it was jerking and hesitating in low gear, BUT i have today disconnected my maf sensor and its driving like a brand spanking new car... im loving it, so clearly thats what the problem has been,
Are these parts easy enough to clean with spray ? or would i be best to buy a new one.
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      06-09-2016, 08:04 AM   #16
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better to replace than try cleaning tbh.
My experience of all air flow sensors no matter the manufacturer once its broken its impossible to "fix"
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      11-07-2016, 01:54 AM   #17
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Looking to buy a new MAF for my E92 325d. Looked up the part number on realoem,

13627788744 maf. Will I also need the gasket ? 13712247395

And, looking these up on ebay, the average price is around £40 for the maf, I did see one for £150.

Any suggestions on where to source from please ?

Thanks
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