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  1. #1
    Registered Member One Ring
    Join Date
    Jul 07 2019
    AZ Member #
    499147
    My Garage
    BMW e36 convertible 328i
    Location
    Cape Town

    Audi A4 1.8T B6 Map / boost sensor wiring help

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    Hello Guys. I recently purchased a 2004 Audi A4 B6 1.8T . The car is not in a prestine condition but I hope to get her there soon. The previous owner did not pay too much attention to the vehicle and I am hoping to sort out all the minor odds and ends to have this vehicle in a perfect condition. So far I have had my turbo rebuilt , replaced PCV and PRV,* N75 valve ,oil and spark plug change. However I noticed that the car was using alot of gas*and I had some gas*fumes coming from the exhaust. Recently the car overfueled and did not want to start. I checked the spark plugs and they seemed to be wet with fuel. At first thought it might be injectors that are stuck open but they are fine. I did a fuel pressure test and they seem to hold pressure well with no injectors leaking. I*then had the car scanned with a VAG and the got the following codes:



    - Manifold pressure/ Boost sensor ( G31 ) P0238 - 001 - Signal too high

    - Manifold Barometric pressure sensor* ( G71) (F96 ) P0106 - Implausible signal



    I then realized it could be the* MAP sensor wiring that seemed dodgy to me in the first place. That is the sensor that*mounts on the SMIC (intercooler). The wires have been cut before the harness that plugs into the sensor but the wires colors do not match where they are joined*( seemed like the previous owner did some strange wiring himself) . I have done some research online and most people say that the voltage at the wires should be with ignition turned on*:



    5V ( power wire from ECM)*

    1-5V ( signal return)

    0 V ( ground wire)



    The most common MAP sensors have a 3 pin but this model Audi has a 4 pin.I have no idea what the 4th wire is supposed to do.**I then got my multimeter and the*voltage readings are completely different from what most people say the voltages should be. My voltage readings and 2 tone wires connections*are as follows:



    1) Brown/Black - connects to Brown/Yellow = 0.25V

    2)Blue /White- connects to Blue/Brown = 12.23V

    3)Purple/ black* - connects to yellow/grey = 0.02V

    4)Green/Black - connects to Grey/Red =0.50V



    My concern is that the power wire seems to be the 12V wire. Is this normal for this car? Should it be 12V and not 5V? I would also like to know which one of these wires is my signal wire? The car feels like it is in limp mode because of this. I really need some help with these wires. I would hate to purchase a new sensor and have the new one blown because of incorrect wiring.* Any advice would be appreciated. Or if someone with the same car can test the voltages at their sensor and report back too me would make my life so much easier. Thanks in advance

  2. #2
    Veteran Member Four Rings jjvwg's Avatar
    Join Date
    Jan 01 2012
    AZ Member #
    86019
    My Garage
    2004 A4 Avant
    Location
    CO

    Does the map sensor have 4 prongs in the electrical connector portion also? Or could the previous owner done something crazy with the wiring and added something?Was going to help but I only have wiring diagrams for the AMB motor and it appears your not in America and probably donít have the same motor code. The AMB MAP sensor is only 3 wire...seems weird that a different motor code that is still a 1.8t would need more wires for the same sensor.


    Sent from my iPhone using Tapatalk
    | 2004 A4 Avant | Gloss Dark Grey |
    | 2.7t K04 swap | 034 RSB | Apikol snub | 17z BBK |Vogtland GT1 Coilovers | Moog adj. UCA's | Peeler reps |

    | 2011 A4 Avant | Brilliant Black | Vogtland Coilovers | RSE's | 034 Sway/tranny mount | Q5 brakes |

  3. #3
    Registered Member One Ring
    Join Date
    Jul 07 2019
    AZ Member #
    499147
    My Garage
    BMW e36 convertible 328i
    Location
    Cape Town

    Hi there. Thanks for the reply. The Map sensor connector has 4 prongs as well. It all appears to have come this way from the factory. The sensor with 4 prong plugs in perfectly to the the 4 prong connector. The wires were split though on the connector side and the color codes do not match. My motor code starts with BEX I am not sure if it is the same but most of the tutorials for the AMB motors has worked for my car.

  4. #4
    Registered Member One Ring
    Join Date
    Jul 07 2019
    AZ Member #
    499147
    My Garage
    BMW e36 convertible 328i
    Location
    Cape Town

    I have done some research on Audizine and it appears that the BEX is a tad more advanced than the standard 1.8T. But other than these differences it is basically the same.

    The following differences can be found between standard models and the BEX:

    Additional Intercooler beneath the airbox
    Larger Turbocharger
    Different Exhaust Manifold
    Larger Injectors
    Larger Front Brake Discs
    Different Flywheel and Pressure Plate
    01E Transmission with shorter Final Drive



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