will this work? MAF fix inside
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1st Gear
Joined: Mar 2007
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will this work? MAF fix inside
Ran across this article.. cheap fix for the time being?
http://users.vnet.net/w123d/w123d/vw/repair/mafrig.htm
http://users.vnet.net/w123d/w123d/vw/repair/mafrig.htm
I got tired of driving around in limp mode while I wait for my new MAF to show up, so I made a poor man's "MAF Sensor" out of a wire and a couple of crimp-on terminal connectors. This applies to a '99 New Beetle TDI. Others should be similar. 
) is the "return signal." This is the really important one...the one that the ECU looks at to determine airflow. The 12v supply simply heats the sensor. The more airflow through the sensor, the more it's cooled and the lower its resistance. The regulated 5v supply from the ECU flows through the MAF, and part of it returns via the "highest numbered" wire. At low airflow, there is more resistance through the sensor and the return signal is therefore less of the original 5v finds its way back to the ECU. At high airflows as much as the full 5v can make it back to the ECU. I used a multitester to identify the various wires and their functions. The 12v and 5v wires are only "hot" when the key is in the "on", or "run" position. MAKE SURE YOU DON'T USE THE 12V WIRE!!!! Unless fried ECU sounds tasty to you, of course. On my car the 5v supply wire is the 2nd highest numbered wire. I simply jumped it to the "signal return" wire, and presto! Instant "maximum airflow"!!! Just use a few inches of wire with a very small spade connector at each end. If your MAF goes haywire out on the road, just unplug it (with the engine off and the key out) and jump the #4 and #5 terminals on the harness. You should be able to drive around quite happily like this until you can replace your MAF. You will have a Check Engine Light. Another odd side-effect is that your boost won't zoom up to a "peak", and then drop back down to a "sustained" level. Instead, it'll climb to the "sustained" level a bit more slowly than you're used to seeing and then just stay there. You'll also see a little more smoke than usual, and I would imagine your fuel economy would be down a bit. The general confusion to the ECU will also result in a bit less power, but it's certainly a vast improvement over Dead MAF Mode. Enjoy your trip, and fix it when you get the chance! Carry the jumper in your tool kit. And I would strongly suggest that you use a multitester to identify the terminals BEFORE you have a problem out in the boojum trees somewhere! The highest numbered wire is the signal return wire. (You can faintly see the numbers molded in the plastic plug in the 2nd picture.) You jump it to the 5v supply wire...the one that supplies a constant 5 volts DC between the wire and the engine block when the key is "on." It should be the one right next to the signal return wire. DO NOT JUMP TO THE 12 VOLT WIRE!!!! -mickey
Basically, you disconnect the MAF harness, and then jump the 5.0v power supply from the ECU directly to the wire that leads BACK to the ECU. This simulates a constant "maximum airflow" condition. You'll get a Check Engine Light, and a bit more smoke than you're used to. But you'll also have boost and power, which beats crawling around like you've peed yourself on your vacation!
On the A4 MAF, there are 4 wires. One is a ground. One is a 12v power supply to heat the Hot Film sensor. One is a 5v supply that passes through the MAF, which acts as a variable resistor to ground out part of that signal depending on the temperature of the hot film, which will vary with airflow. The highest numbered wire (familiar to Epsilonians ) is the "return signal." This is the really important one...the one that the ECU looks at to determine airflow. The 12v supply simply heats the sensor. The more airflow through the sensor, the more it's cooled and the lower its resistance. The regulated 5v supply from the ECU flows through the MAF, and part of it returns via the "highest numbered" wire. At low airflow, there is more resistance through the sensor and the return signal is therefore less of the original 5v finds its way back to the ECU. At high airflows as much as the full 5v can make it back to the ECU. I used a multitester to identify the various wires and their functions. The 12v and 5v wires are only "hot" when the key is in the "on", or "run" position. MAKE SURE YOU DON'T USE THE 12V WIRE!!!! Unless fried ECU sounds tasty to you, of course. On my car the 5v supply wire is the 2nd highest numbered wire. I simply jumped it to the "signal return" wire, and presto! Instant "maximum airflow"!!! Just use a few inches of wire with a very small spade connector at each end. If your MAF goes haywire out on the road, just unplug it (with the engine off and the key out) and jump the #4 and #5 terminals on the harness. You should be able to drive around quite happily like this until you can replace your MAF. You will have a Check Engine Light. Another odd side-effect is that your boost won't zoom up to a "peak", and then drop back down to a "sustained" level. Instead, it'll climb to the "sustained" level a bit more slowly than you're used to seeing and then just stay there. You'll also see a little more smoke than usual, and I would imagine your fuel economy would be down a bit. The general confusion to the ECU will also result in a bit less power, but it's certainly a vast improvement over Dead MAF Mode. Enjoy your trip, and fix it when you get the chance! Carry the jumper in your tool kit. And I would strongly suggest that you use a multitester to identify the terminals BEFORE you have a problem out in the boojum trees somewhere! The highest numbered wire is the signal return wire. (You can faintly see the numbers molded in the plastic plug in the 2nd picture.) You jump it to the 5v supply wire...the one that supplies a constant 5 volts DC between the wire and the engine block when the key is "on." It should be the one right next to the signal return wire. DO NOT JUMP TO THE 12 VOLT WIRE!!!! -mickey
4th Gear
Joined: Nov 2005
Posts: 3,393
From: Columbus Ohio
RE: will this work? MAF fix inside
It'd probably work, you can disconnect the maf too and the car will run.
I wouldn't drive it any further that say, to the parts store to buy a new maf.
Really, I wouldn't even do that, but you may be braver than I.
I wouldn't drive it any further that say, to the parts store to buy a new maf.
Really, I wouldn't even do that, but you may be braver than I.
Thread Starter
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1st Gear
Joined: Mar 2007
Posts: 398
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RE: will this work? MAF fix inside
well i have had mine unhooked for bout a month and other than a cel and bad shifting its fine... 5th gear is the only one that ***** up.. hopefully my MAF will come today, or this week.. damn backorder bs[:-]
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1st Gear
Joined: Mar 2007
Posts: 398
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RE: will this work? MAF fix inside
ok so i finally found the torx bit to fit the damn screws and got off my lazy butt to clean it.. i soaked it in rubbing alcohol and used the electronic cleaner spray along with some small q-tips, and etc. Cleaned all the corrosion off.. PRESTO! reset the cel, and she is driving great again, now i cant even feel her shift... <3 Cleaning worked this time, guess ill have a extra maf around just in case.
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