P0238 overboost issues

[WhiteM57]

Hey guys….

Sorry to weigh in with such a lengthy, and presumably common post but Im haemorrhaging money (and sanity) at an alarming rate.

Octavia 2.0 BKD140, 2010 with the dreaded P0238.

Actual reading…P0238 Turbocharger boost pressure sensor circuit high - intermittent
also I had a P1592 Boost Pressure sensor coherence between atmosphere and boost pressure
this has since disappeared and not returned ….yet!

The story so far…
Turbo replaced with new unit (guaranteed re-man unit from reputable outlet)
EGR valve replaced with new unit, flow restrictor plate fitted too in an attempt to keep things clean, map sensor replaced with new unit and maf substituted with known good unit. All earthing points cleaned and re-made and map sensor wiring checked as far into loom as possible.
Although things have improved slightly it still throws the code around 2800 rpm.
I have checked as well as I can all vac pipes & and intercooler pipes & hoses.
What puzzles me though are the live data pressure readings as follows….

Engine off, Ign On           Atm.Pressure                  979.2 mb
                                        Inlet Man Pressure        1152.6 mb

Engine Running T/O        Atm.Pressure                 979.2 mb
                                        Inlet Man Pressure       1162.8 mb  

Engine Running 2krpm    Atm. Pressure                979.2 mb
                                        Inlet Man Pressure        1642.6 mb 

am i right in thinking atmospheric and manifold pressure should be the same when not running?  

Im guessing someone has had these issues before?            

would be eternally grateful if anyone give me any pointers before I nail up the noose

Thanks
Mark

 

[WhiteM57]

Just to add.... I have some live data readings from the boost map showing a definite overboost

 

Tickover

Desired boost 1040mb

Actual boost    1118mb

 

2500rpm

Desired boost 1162mb

Actual boost    1458mb

 

4000rpm

Desired boost 1438mb

Actual boost    2458mb

 

After substituting the map sensor with the original again the figures are slightly reduced

but the gap between desired and actual is pretty much the same

 

This morning Im going to attempt a rewire of the map sensor back to the ecu

 

Any thoughts guys?

Cheers

M.

[WhiteM57]

Good news... all sorted, continuity issue on -ve wiring from ecu to map sensor plug, rewired, soldered and taped, road tested & back on song !