P0234 - Overboost

[alexx88]

Hi guys,

First posts around here. I just had a Quantum stage 1 remap done and also the timing belt serviced, oil and filters changed as well. One day after having everything done I hit a major pothole (steel rim got seriously bent) and a few hours after, the car started going into limp mode when driven hard (WOT in 4th gear at about 3k) and throwing DTC P0234. Turn the ignition off, restart it and everything is fine. Try to drive it hard again and, given a few minutes, it goes back into limp mode.

One things that pops up from the logs is that there is quite a difference between desired boost and actual boost.

These are the DTCs of the engine module:

Saturday,07,February,2015,22:06:08:10074
VCDS Version: Beta 11.2.0
Data version: 20110305


                Address 01: Engine       Labels: 06F-907-115-AXX.lbl
Control Module Part Number: 1K0 907 115 Q    HW: 8P0 907 115 B
  Component and/or Version: 2.0l R4/4V TFSI     0020
           Software Coding: 040300031C070160
            Work Shop Code: WSC 08708 803 00000
                      VCID: 346318E32CFB
3 Faults Found:

000256 - Mass Air Flow Sensor (G70): Supply Voltage
               P0100 - 004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00100100
                    Fault Priority: 2
                    Fault Frequency: 9
                    Mileage: 101448 km
                    Time Indication: 0
                    Date: 2000.00.00
                    Time: 19:58:33

             Freeze Frame:
                    RPM: 4866 /min
                    Load: 75.3 %
                    Speed: 66.0 km/h
                    Temperature: 94.0°C
                    Temperature: 11.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.224 V

001089 - EVAP Emission Control Sys: Incorrect Flow
               P0441 - 002 - Lower Limit Exceeded - Intermittent - MIL ON
             Freeze Frame:
                    Fault Status: 10100010
                    Fault Priority: 2
                    Fault Frequency: 4
                    Mileage: 101457 km
                    Time Indication: 0
                    Date: 2000.00.00
                    Time: 20:16:07

             Freeze Frame:
                    RPM: 843 /min
                    Load: 14.1 %
                    Speed: 0.0 km/h
                    Temperature: 96.0°C
                    Temperature: 20.0°C
                    Absolute Pres.: 1000.0 mbar
                    Voltage: 14.097 V

000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
               P0234 - 001 - Upper Limit Exceeded
             Freeze Frame:
                    Fault Status: 01100001
                    Fault Priority: 2
                    Fault Frequency: 3
                    Mileage: 101522 km
                    Time Indication: 0
                    Date: 2000.00.00
                    Time: 20:38:06

             Freeze Frame:
                    RPM: 3494 /min
                    Load: 69.8 %
                    Speed: 94.0 km/h
                    Temperature: 96.0°C
                    Temperature: 6.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.224 V


Readiness: 0000 0000

--------------------------------------------------------------------------------
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Address 01: DTCs cleared

You can safely ignore the MAF one, it's from disconnecting the sensor in the garage for a test.

I've added some logs made with VCDS: https://drive.google.com/folderview?id=0B7MXqEtoH8k4fl9PY0s2UTFrNlV5MllFV3JXT1Q5VjlybWtrOWRyQzlTSzRlX1lWaFRYVkE&usp=sharing

Cheers,
Alex

[Llew]

Another quantum map read this
http://www.mk5golfgti.co.uk/forum/index.php/topic,90774.0.html

[alexx88]

Thanks, I've posted there as well, see if the problem was map-related. I've read that stage 1 may reflect underlying issues that the car already had and the map just brings them to light, so I don't want to be quick to blame Quantum for the problem just yet.

I'll be doing another round of logging today, enabling 'turbo' mode in VCDS to get better resolution and also focusing on the zone of max boost in 4th gear, rather than doing runs in 3rd.

[alexx88]

Need to correct myself, the wiring of the MAF is indeed faulty: very badly worn insulation and only one strand of wire left for MAF pin 1. Do you think this may have anything to do with the overboost error?

I've also added two graphs:
1. limp_mode.png shows N75 duty and boost values when it switched to limp mode.


2. wot_pull_ok.png shows a normal pull with no issues from the following day.


3. max_boost_pull.png tries to reproduce the conditions at '1', but car was fine. This was also done the following day.


Any ideas?