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Hey! I`ve got some problems with my e38. The car was kinda short on power when pushing the gas pedal. I suspected the MAF, so i changed it. But it still does not get any better. I cleaned the car`s "brain" with electro cleaner. And now the car works just fine. But without the MAF connected. When I connect the MAF, the car won`t start. Any suggestions yo what to look for next??

Submitted: 45 days and 10 hours ago.

Category: BMW

Value: $21

Status: AWAITING CUSTOMER ACTION

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Optional Information

Year: 1999
Make: BMW
Model: e38 735I
Engine: M62 3,5L

Posted by AMEDEE 44 days and 13 hours ago.

Info Request

Hello!

Did you say that the engine will not run if the mass air flow sensor is connected?

44 days and 12 hours ago.

Reply

Yeah! That`s right. I`ve tested with a brand new mass air flow sensor. The car works fine without the MAF, but uses more fuel offcourse

Posted by AMEDEE 44 days and 12 hours ago.

Info Request

Where did you get the new mass air flow sensor from?

44 days and 12 hours ago.

Reply

From a friend. He`s got a e39 M5. He got a new one, but crashed his car before he got the time to replace it. So he gave it to me. Checked the part number, and it`s the same MAF

Posted by AMEDEE 44 days and 12 hours ago.

Info Request

DO you know where he got it from?

44 days and 12 hours ago.

Reply

Yes, he said he got it from a local bmw dealer. So I believe it`s original

Posted by AMEDEE 44 days and 12 hours ago.

Answer

Well, this does not sound right.

Usually, when vehicles run worse or do not run at all with the mass air flow sensor plugged in compared to when the mass air is disconnected, this indicates the mass air flow sensor is bad!

44 days and 12 hours ago.

Reply

Yeah, I know. Do you have any tips for what else to check? By the way, I\ve just changed my cam sensors, so that should not be thought of as a possible fault

Posted by AMEDEE 44 days and 12 hours ago.

Answer

I would recommend to check for codes, check fuel pressure and engine vacuum.

44 days and 12 hours ago.

Reply

I`ve thought about the cable to the MAF. Maybe it`s broken. How can I controll this? What values too look for with a multimeter?

Posted by AMEDEE 44 days and 12 hours ago.

Answer

Well, we will need to start by checking the wires that go to the mas air flow sensor for power with the key on.

44 days and 12 hours ago.

Reply

Yes, but what result can I get if the wires are okey? I`ll go out to my car right now, and check what values I get

Posted by AMEDEE 44 days and 12 hours ago.

Answer

Well, we not only need to check the wires going to the mass air flow sensor, we need to check the entire circuit. THis would include checking the wires from the mass air flow sensor back to the computer. This will ensure that the wires to the mass air flow sensor are ok and that the wires from the mass air flow sensor to the computer are good.

44 days and 12 hours ago.

Reply

Okey.. I`m looking for tools here. Do you know where I can find a circuit map for this?

Posted by AMEDEE 44 days and 11 hours ago.

Answer

I have access to bmw wiring diagrams. But I don't have any info for this model 3.5 liter.

You could all the dealer or look it up on line. I know that alldata pro or mitchell on demand might sell you information for individual vehicles for cheap.

44 days and 11 hours ago.

Reply

Now I`ve checked the contact that`s plugged to the MAF: I was standing in front of the car. The contact pointing towards me the way it`s to be connected to the MAF. I got these values: First contact 0 Volts, Second 4,98 Volts, Third 0 Volts, Fourth 11,83 Volts, Fifth 4,98 Volts. So here`s 2 wires with no values. But is this something wrong, or are these wires for some sort of reading signal?

Answer

THese wires are most likely signals back to the computer from the mass air flow sensor. SO this does sound right. With the mass air flow sensor unplugged, there will be no readings on these wires.

Accepts:
Expert:	AMEDEE
Pos. Feedback:	100.0 %
Answered:	10/9/2009

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