MAF sensor error.

[drocket77]

I replaced the MAF sensor with an after market one, and it is still not reading any flow. I replaced the 2 rubber boots, and made sure it was flowing . If I place my hand over the intake before the MAF sensor, it is instantly sucked onto the hose, and car stalls. So I know there is good flow, and I do not hear any leaks. So I now hook up a Bi-Directional scan tool Launch X431 and go into the MAF sensor while the car is running to see how much flow, and low and behold ZERO kg/h. What are the chances of this MAF being DOA? And what should the resistance be on the MAF sensor.

I wish I could export the data into windows, but there is no option for that. But take my word, I had the graphs on the screen at the same time and as RPM went up, my MAF stayed at 0(zero) Kg/ h.

I would also like to know the EXACT pinout on the ECU, but I am have a hard time finding one. I want to check for continuity from the plug on the MAF to the ECU. I think I traced one by color, and that harness C pin 27, but the others are a pain. Thanks in advance for any help.

[drocket77]

OK, so no luck figuring anything out.I have been trying to do a bit here and there when time and temp permit. Here is what I have done so far.

1 Hook up 2 different scanners, and both are reading 284.3g/s. So I unplug it and read it again, now it reads 0.0
2. Hook up old MAF sensor, and it reads 0.1g/s, unplug it read it again, and now it reads 0.0.
3.Hook up MAF sensor from step #1, start the car, it still reads 284.3g/s. I now choke off the intake before the MAF sensor, car stalls, but the readings stayed the same at 284.3 and with the car off ignition in the on position, it is still reading 284.3

Now I do this...

Trace the wires to the ECU. I notice there is a red wire cut, but no where it seems to go. It is connected into a harness, and seems to be going with a Green/Brown wire. Now there are a few Green/Brown wires, and one is on the MAF sensor.


I am getting 12v and 5v on the respected wires, but I am not getting anything on the remaining wires.

So in "conclusion", I have no conclusion. I have a hunch that the previous owners son tried to turn this into a "tuner", and may have had the ECU flashed. What vs.# should the ECU be reading on the scanner? And would it be a waste of mobney to take it to the dealer and just have them save current flash, and then re-flash to stock?
Also on the very left hand side of the pic, you can see a green wire with a metal bracket. Why would anyone use one of these in a real world situation? I thought most people would understand that these would be live wires with chance of moving, and should only be used for testing.....

[pokeybritches]

You can find the wiring diagrams here: https://www.newtis.info/

I've attached a picture of the wire colors and what they should be. You'll also want to check for a voltage drop across the wires, not just continuity.

[RobMCoupe]

See if this is useful. Let me know if you need anything else.

[drocket77]

Thanks for the help. Here is the Voltage drop.... Left is at the plug, right is at ECU

1= 5.06 ---5.05
2= 14.03----14.04( was moving from .03-.05)
3= .04 ---.01
6= 5.05 ---5.05

And that other wiring diagram is for a 2006, and the colors are different, but I would assume that the positions would be the same so it does help some.

Now here is the other oddball thing. I will see if I can grab a screenshot of the ECU vs # and date. It looks a bit weird, unless the dealer flashed it after an update in 2014.



I have also driven the vehicle about 20x for 600 miles since last reset, and there a few things still not in ready status. I am about to just park the damn thing and fix my other car, cause I know whats wrong with that. Head gasket, and that is a bit of work, but it would be 100x easier then an electrical problem.

[drocket77]

OK, so after talking with 2 people. 1 a BMW specialist, the other a Euro Specialist, and both are leaning to bad ECU, bad wiring.... And the bad part is they can not get me in until 3rd week in March at the earliest.

[pokeybritches]

Originally Posted by drocket77

OK, so after talking with 2 people. 1 a BMW specialist, the other a Euro Specialist, and both are leaning to bad ECU, bad wiring.... And the bad part is they can not get me in until 3rd week in March at the earliest.

Your MAF signal voltage looks low. Output should be about 1.2V at idle, which is about 20-25 kg/hr. This of course depends on temperature and altitude. I'd start by replacing the sensor.

Based on your measurements, wiring looks ok, although voltage drop across the ground wire would be nice to see too. You can measure the wire itself, one end at the MAF connector and the other at the ECU. ECUs rarely go bad unless they have been exposed to the elements or improperly wired.

[pokeybritches]

You can download a free copy of ByteLogger from Renovelo's site https://www.renovelo.com/bytelogger/

Log everything related to the MAF sensor and IAT. If your other parameters look normal, the issue is probably the sensor itself.

[drocket77]

What i meant by bad is that the previous owner tried to make this a tuner and may have flashed the ecu by bypassing the maf. The digital date on the ECU is 2014. So unless this was flashed at the dealer in 2014, it should have a date of 2010 at the ltest for recall work that was done. I have a recall sticker in the engine bay.

[pokeybritches]

Alpha-n tunes only cause the ECU to ignore the MAF sensor readings. The MAF will still work if it's plugged in and functioning correctly from a hardware standpoint. The ECU accepts the MAF output as an input and has no control over the MAF sensor.

You can try reflashing the latest software version into the ECU via WinKFP, but I think you'll find the sensor is the issue.

[pokeybritches]

Revisiting this thread: 284.3 g/s is 1024 kg/hr, which is the maximum MAF reading, >4.6V. I'm guessing one MAF sensor has an open circuit and the other has a short.

Amazon has $30 MAF sensors that will work for a while, though I don't recommend them as a true OEM replacement.

FAERSI Mass Air Flow Sensor Meter MAF for BMW 330i 330Ci 330xi Z4 X3, 2003 2004 2005 2006 330Ci 3.0L, 2002-2005 330i 330XI 3.0L, 2004-2006 X3 3.0L & 2003 Z4 3.0L L6 https://www.amazon.com/dp/B07KYGS7Q9..._btZuEbSKM54N7

[drocket77]

Reviving this, as it is still an issue. I have 3 different MAF sensors and 2 IAC's. I have played around with different setups, and still can't find a fix.

I have Winkfp, INPA, NCS Expert and BMW Coding.
The problem with all of these is that the programs are German, and I do not comprehend it. I am assuming WinKFP will write an update to the ECU, but I am still trying to figure out the software. I would rather take my time, and not brick my ECU.

[drocket77]

So I gave it a go and ordered another MAF sensor. Well the diameter is bigger than the hoses. I just plugged it in and checked it it would work, and it did. I went to PEPBOYS, and bought a small 4 inch(length) reducer.

Now onto the front end damage.

[pokeybritches]

Which model do you have, and which model MAF sensor did you purchase?

[drocket77]

The one you suggested, and that was the first one i bought back in November, but it didn't fit, so i never plugged it in. Oh well you live and learn. Thanks.....

Now onto the physical parts... its a pain in the rear trying to find a decent painter.

[pokeybritches]

The reason I ask is, the 2.5i has a different MAF sensor than the 3.0i. The 3.0i MAF sensor can work just fine on a 2.5i, but the ECU needs some minor tuning changes to make it work.

[drocket77]

I have the 3.0. Since the previous owner had a CAI, I assumed the pipes were stock, and probably ordered the correct MAF first. Unfortunately the only color Pepboys had was blue, so I will be ordering some black tubes and redoing the whole intake in black.

[drocket77]

Now that the cosmetics are done, I took it for a test drive after resetting adaptations. It drives fine under 4k rpms, but when I give it full throttle it sputters now, and misfires. I have a video of the cylinder firing. #2 seems odd.

I am also thinking since the car was used without a MAF for a long time, and the oil smells of gas, there may be some sludge. I will be doing a an oil change and spark plugs next week, and hopefully that helps.