Boost Pressure Problem

**CristianTM** · 25th September 2009, 22:24

Hello fellas,

My engine is Z19DTH, 150hp, Vectra-C 2005 year car.
I hope in this forum to find a solution at my little problem.
Well, the car works fine, BUT, ...from a while the Boost Pressure not equal with Boost Pressure Command and this despair me

I need a professional advise, not a assumption ..if possible!
I attached the main data form a recent diagnose. In the past must say the boost pressure command it was equal with boost pressure sensor (maybe +/-1 unit), now permanently different !
http://img85.imageshack.us/img85/3953/rpm1.jpg
http://img7.imageshack.us/img7/7598/rpm2.jpg
http://img42.imageshack.us/img42/6113/rpm3.jpg
http://img32.imageshack.us/img32/5043/rpm4.jpg
http://img2.imageshack.us/img2/7730/rpm5.jpg
http://img2.imageshack.us/img2/2728/rpm6.jpg

CristianTM.

**CristianTM** · 27th September 2009, 15:42

Nobody ? Hmm....The answers waiting!
I think MAF or EGR are the problem, but both have some money value and I don't afford to change both and the same time.

CristianTM.

**Big Sig** · 27th September 2009, 15:50

Have you tried to clean the boost sensor yet? It may just be covered in dirt.

**CristianTM** · 27th September 2009, 19:23

Originally Posted by Big Sig

Have you tried to clean the boost sensor yet? It may just be covered in dirt.

The Boost Sensor was dirty, but after cleaning NO effect ! No effect for CAR, no effect for diagnose. More effect had EGR cleaning !
The strange ting is ... I diagnose three different cars with engines: Y20DTH, Z19DTH and Z19DT and ... all three had difference of Boost Pressure Command and Boost Pressure.

CristianTM.

**CristianTM** · 27th September 2009, 20:53

My newer conclusion, after I reading some old and new live data:

15.12.2008 (good response)
Engine Speed: 2608 RPM
Calculated Air Flow: 144 Kg/h
MAF Sensor: 144 Kg/h
Barometric Pressure: 101 kPa
Boost Pressure Command: 120 kPa
Boost Pressure: 120 kPa
EGR Position Commandes: 37%
EGR Pulse Ratio: 39%

02.06.2009
RPM Engine Speed: 2583 RPM
Calculated Air Flow: 148 Kg/h
MAF Sensor: 148 Kg/h
Barometric Pressure: 98 kPa
Boost Pressure Command: 120 kPa
Boost Pressure: 119 kPa
EGR Position Commandes: 38%
EGR Pulse Ratio: 38%

25.09.2009 (bad response)
Engine Speed: 2580 RPM
Calculated Air Flow: 165 Kg/h
MAF Sensor: 165 Kg/h
Barometric Pressure: 100 kPa
Boost Pressure Command: 120 kPa
Boost Pressure: 130 kPa
EGR Position Commandes: 38%
EGR Pulse Ratio: 38%

From these measurements the only conclusion is the MAF have different values from previously dates and can be the cause of bad boost pressure.

CristianTM.