[Artermis]

Hi Lee,

In answer to your questions. Hopefully I've tried to cover as many of them as I can before running out of time and daylight for today.


1. If you go into the data blocks now after the boost pressure replacement what is your ignition on reading on the sensor that you say has some variation on ?

OK so today the two values are slightly different - we have a different weather system over us now with much more settled weather and colder temps.

Therefore today we have an absolute press of 1030.2 (this is the fixed value, 999.6mbar in earlier post).

The variable value, i.e. the one that does seem to change is at 1122.0mbar, when car is running. When the fault is generated, at first ignition on, this value increased to 1132.0mbar.

If I clear the fault, engine on or off, the fault doesn't repeat until ignitionoff and on.

2. Is the replacement boost sensor you have a got a good make ? Not ting tong ?

It's unbranded I'm sorry to say. You know I have two of the replacements, as I mistakenly bought two. I also have a 'spare' map sensor off an Alfa 156 which is BOSCH. I still have the genuine BOSCH that came off the A8.

When I've checked the resistances between the pins both BOSCH sensors show about 1ohm lower than the spare generic sensor I've got. Both BOSCH sensors are comparable with each other. I've not tested the sensor on the car but I can't see it being different to it's twin.

Unfortunately the Alfa sensor plug isn't compatible with the A8 to test.

3. You are using vcds ??
On the first page is advanced measurements highlighted ? So you can go into the readings like this ......

Yes I am using VCDS and HEX-CAN cable. I don't have the advanced measurement option highlighted, it's greyed out.

When I go into the measurement blocks I can look at group 10 and see the following:

15:02:48 Group 010
0.0 mg/str Mass Air / Rev.
1030.2 mbar Absolute Pres.
1122.0 mbar Absolute Pres.
0.4 % Duty Cycle
Wednesday,28,December,2016,15:11:36:33490
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.3.0 (x64)
Data version: 20140905

The second of the two absolute pressure values, 1122.0mbar responds to throttle. For a car in limp mode it responds as I've expect, i.e. vac in response to throttle input. I can only test at stationary as the front end is in bits to access the pressure sender and it's on jack stands!

The other absolute pressure value, 1030.2 is fixed / constant and doesn't react to engine or input whatsoever.

Groups 10 and 11 show this (don't know what difference between 10 and 11 is). This is five mins later so engine is a bit warmer than above.

15:07:36 Group 010
552.3 mg/str Mass Air / Rev.
1030.2 mbar Absolute Pres.
1111.8 mbar Absolute Pres.
0.4 % Duty Cycle

15:07:36 Group 011
672 /min RPM
938.4 mbar Absolute Pres.
1111.8 mbar Absolute Pres.
1030.2 mbar Absolute Pres.



4. Before you do that.... with ignition on you need to check at the boost sensor ( disconnected )plug that you have the ' strong' 5 volts supply and a ' strong ' earth

OK, so I've found out my test light is broken, I'll have to ask my dad for help to test that much.

I have tested the other pins at the plug. Haven't broken into the ECU you.

The pins are as follows:

pin 1 - brown w/blue = 0.04v
pin 2 - white w/green = 5v
pin 3 - yellow w/red = 5v
pin 4 - white w/yellow = 5.6v

stands to reason that pin 1 is the earth.