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Old 12-16-2014, 09:23 PM   #1
DMahoney
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MAF Sensor Issue - Please Help

Long story short my sucking jet pump broke and I had to fix it. I also replaced both intake boots and such. I put everything back together but I had trouble getting the MAF sensor on the new intake boot and airbox. I pushed and pushed and I gently hit it with the screwdriver on the sides.

I got everything back together and had a problem.. A couple times I noticed that when I hit the accelerator when I was in neutral it didn't do anything. It didn't rev up ect.. But it didn't happen again. I got a code and it was P0102. I cleared it a few times and it kept coming up. So I brought up my u-scan data and got a reading of zero:
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I will buy cleaner tomorrow and see what's up, but I'm afraid I may have broke it when I tapped on it... I certainly don't have a money to buy the correct (not el-cheapo) sensor right now.

I looked at the male and female ends of the connections and they were okay. My question is, if it happened to be that the sensor itself was fine but the electrical connector was bad, how would I change that? I can't find anything on it. Also, how can I test the actual connector that feeds under the engine? Do I just book a voltage tester up to it?



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Old 12-16-2014, 10:25 PM   #2
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Do not bother cleaning the MAF, it will not help.

Probably broke/cracked internal solder joint in the MAF?

If you have a 3 wire MAF, there should be 12 Volts, Ground and MAF output.

I prefer to use a test like to confirm the 12 Volts and Ground rather than a meter. Or use both, test light to load the circuit with the Voltmeter to verify what the actual measurement is.

Wiring could have broken in the harness or the MAF could have been damaged. Might be able to watch the U-Scan graph while wiggling, moving/pulling the wiring and see if the graph jumps with data.

If you have an early 325 you may be able to use the Bosch Hyundai sensor, search the forum here for the info.
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Last edited by jfoj; 12-16-2014 at 10:27 PM.
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Old 12-16-2014, 10:42 PM   #3
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For what it's worth, I have the same issue. Been chasing the same thing for ages, and jfoj has helped me out a lot. For me, it is more than likely a broken wire in the harness. I have used a brand new MAF, and I still had the same error. Still have not been bothered to fix the harness break.
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Old 12-16-2014, 10:57 PM   #4
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If the break is in the harness, it is most likely between the MAF and the wire box near the throttle body.

The problem is the wires break inside the insulation and it is hard to find.

You need to get needles to prob the wiring to look for the break and/or use the wiggle, pull, pressure test on the wiring to try and narrow down where the problem may be.

The OP may have broken something in the MAF but it is worth checking for power and ground to the MAF connector first.
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Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Old 12-16-2014, 11:04 PM   #5
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Yup, you are correct. It's somewhere in the line between the MAF and wirebox.

@OP; do as jfoj says; test the MAF connector. If you access to another MAF without buying, try it as well. I made the mistake of assuming I had a dead MAF, and bought a new one only to realise it didn't solve my problem. Good luck!
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Old 12-17-2014, 09:56 AM   #6
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Thanks I will later today.. It's raining right now..


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Old 12-17-2014, 10:00 AM   #7
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Is it at anyway possible that it could be the jet sucking pump?


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Old 12-17-2014, 11:06 AM   #8
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Nope, unless there is ZERO air moving through the MAF.
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Old 12-18-2014, 04:09 PM   #9
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I haven't gotten around to checking the connections on the sensor yet or anything like that because it still raining, but I had a question. I noticed that if the car is either in Drive, neutral, or reverse, or even park, and I have my foot on the brake even a little bit and push the accelerator, nothing happens. The RPMs don't move , there's no noise, nothing. Could that be a jet sucking pump issue? Or just MAF ..?


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Old 12-18-2014, 04:13 PM   #10
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Jfoj will weigh in more on this, but from my (relatively little) experience, the MAF failing shouldn't have too huge of an issue. Your car will run on a factory mapped setting if the MAF is disconnected. (So mine is on factory mapped 100% of the time because I'm too lazy).
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Old 12-18-2014, 04:17 PM   #11
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Quote:
Originally Posted by DMahoney View Post
I haven't gotten around to checking the connections on the sensor yet or anything like that because it still raining, but I had a question. I noticed that if the car is either in Drive, neutral, or reverse, or even park, and I have my foot on the brake even a little bit and push the accelerator, nothing happens. The RPMs don't move , there's no noise, nothing. Could that be a jet sucking pump issue? Or just MAF ..?
Some of the engines will go into a Limp mode if the MAF is disconnected, usually triggering lights on the dash.

Some of the engines will run fine with the MAF disconnected.

But if you had the lower intake boot off, you should split the upper and lower boot at the collar, take a good flashlight and look down the lower boot and make sure the flap on the side of the lower intake boot did not get caught and folded back toward the inside the throttle body.
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Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Lower hose temp switch O-ring - BMW #13621743299
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Old 12-18-2014, 08:10 PM   #12
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Yeah I double checked the lower intake boots position.. And I felt around with my finger also to make sure . :/The MAF sensor does read 0 though like I said on the live data..

I just know that if I touch the brake and accelerator at the same time in any manner the car doesn't go anywhere. There's no acceleration whatsoever. I just didn't think the MAF sensor you did that if it was completely blown or anything.. That's why asked if the Jet sucking pump & brake booster etc. had anything to do with it.


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Old 12-18-2014, 08:25 PM   #13
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Quote:
Originally Posted by DMahoney View Post
Yeah I double checked the lower intake boots position.. And I felt around with my finger also to make sure . :/The MAF sensor does read 0 though like I said on the live data..

I just know that if I touch the brake and accelerator at the same time in any manner the car doesn't go anywhere. There's no acceleration whatsoever. I just didn't think the MAF sensor you did that if it was completely blown or anything.. That's why asked if the Jet sucking pump & brake booster etc. had anything to do with it.
I think what you are seeing is a fail safe mode because the MAF reading is 0. Or at least the DME is confused about things. Looks like it is time for a loaner, test or new MAF.
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Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Old 12-20-2014, 01:03 PM   #14
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Okay. Well I made a new thread asking if anyone in my area can help. We will see. I am also hearing a new noise that increases with acceleration. It's like I was humming like noise but I wouldn't call it a humming, it's really weird. Happened after the intake boot repair...


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Old 12-21-2014, 12:33 PM   #15
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How do I test the MAF sensor with this? I really don't know much about electronic so I know is this is my dad's tool but I don't know what to do with it

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Old 12-30-2014, 04:46 PM   #16
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So I got the Jets sucking pump fixed and everything on perfectly. Everything looks good. The mass airflow sensor is still reading zero and when my foot is on the break it does not read the engine or accelerator. The RPMs go all the way down to zero basically..

I have not tested the mass airflow sensor yet my dad is going to help me so I can use his tool.so I'm waiting on him. I don't want to buy a new MAF sensor and have it not help. Most places won't even let you return them. Well least after they're used..

If there's anyone in my area, Massachusetts, with the MAF sensor that I could try out that would be great. I don't see how it could be anything else but the mass airflow sensor
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Old 01-02-2015, 02:11 PM   #17
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Okay so I finally got to check the connector that plugs into the MAF sensor. With the car on accessory, it was about 12 V. When I turn the car on, it went to 0 V. Is it supposed to be at 0 V when the car is on?

Because I mean, when The key was turned into the second position, it had the 12 V. It was only when I turn the car actually on was went and had zero.I didn't know if that was because when the car is on it is supposed to actually send it the opposite way to the computer or whatever. Anyways, just wanted to know if that was normal.
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Old 01-02-2015, 02:31 PM   #18
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This is unconfirmed and this is from the Bentley wiring diagram.

3 wires.

#1 Black wire - possible ground but this comes from the DME. Note this wire appears to have a DME supervisory Voltage present so it may confuse things a bit when taking measurements?

#2 Yellow wire - possible MAF output

#3 Red with a white stripe - 12 Volts from F3 20 Amp fuse in the DME box. Assume this is only hot when the ignition on/engine running. This wire may also have a supervisory Voltage present so it may confuse thing a bit when taking measurements.

You will probably need to back probe the connections and measure/monitor the signals while the MAF is connected and working.

You can use a bent paperclip to slide into the connector from the rear side where the wire exits the connector to attempt to monitor to Voltage while the sensor is operating.

But if there is a broken wire in the harness, using an OBDII tool that can monitor the MAF reading in real time while wiggling the harness is the best way to check for broken wiring.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

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Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 01-07-2015, 08:52 AM   #19
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There any problem with buying a really cheap MAF sensor off eBay just to test it? I mean I'm not going to use it after the test, I will buy a new one from either BMW or maybe Hyundai who knows. Or maybe used OEM one off someone in here or eBay. But just to simply buy any cheap one off eBay is that okay? Just to test it one or two times
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Old 01-07-2015, 08:55 AM   #20
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Also, with the MAF sensor issue affect my pedals? What I mean by that is if I am accelerating, and I hit the brake with my other foot well my foot is still on the accelerator, the car basically stops rpm's and doesn't go anywhere. doesn't stallI hope you guys know what I mean. If I am in neutral with my foot on the brake and try to hit the accelerator to read about the RPMs, it doesn't do anything no noise whatsoever.
I thought it may have something to do with my jet sucking pump being broken because it was but after I fixed it, it's still doing it with this MAF issue...
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