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Enes, Volvo Master Technician
Category: Volvo
Satisfied Customers: 5557
Experience:  18 yrs+. experience as Volvo & ASE Certified Master Technician.
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I have a 2004 XC90 d5. I have ecm6805 boost control faulty

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I have a 2004 XC90 d5. I have ecm6805 boost control faulty flow, I have checked all the vacuum hoses and are all fine and I have replaced the boost valve. When I rev the engine then let off there is boost going back up the air intake
Assistant: How long has this been an issue? How many miles are on the car?
Customer: It’s got worse the last two weeks going into limp mode every time I accelerate, it’s done 140000
Assistant: Are you fixing your XC90 yourself? What have you tried so far?
Customer: I have put a new boost valve/solenoid on, checked the vacuum hoses and they are fine, the actuator moves freely
Assistant: Anything else you want the mechanic to know before I connect you?
Customer: The actuator seems to move twice after revving the engine
Customer: replied 1 month ago.
I have a vacuum reading of 20hg from the vacuum pump
Diagnostic trouble code (DTC) information
Diagnostic trouble code (DTC) ECM-6805 is stored if the pressure measured by the boost pressure sensor is higher than a calculated desired value. This is interpreted as a fault by the control module. The fault is diagnosed by the control module at high engine loads.
Substitute value
Reduced throttle angle.
Possible source
The hoses between the pressure servo for the boost pressure control (BPC) valve and the turbocharger (TC) control valve have come loose or are blocked or damaged
The hoses between the turbocharger (TC) control valve and the charge air pipe (between the turbocharger (TC) and the charge air cooler (CAC)) are blocked or damaged
The pressure servo for the boost pressure control (BPC) valve is incorrectly adjusted
Faulty pressure servo for the boost pressure control (BPC) valve
Sticking boost pressure control (BPC) valve
Faulty turbocharger (TC) control valveIf engine speed (RPM) is above 3500 rpm and the engine is operating at a high load, and if the boost pressure (from the boost pressure sensor) is higher than a designated value, which at maximum boost pressure is approximately 20kPa (2.9psi) above normal boost pressure, this is interpreted as a fault and diagnostic trouble code (DTC) ECM-6805 is stored.Condition
reduced boost pressurePossible source* hoses between turbocharger (TC) and turbocharger (TC) control valve respectively turbocharger (TC) control valve and pressure servo are loose or are blocked/damaged
* faulty turbocharger (TC) control valve
* faulty boost pressure control (BPC) valve pressure servo
* sticking boost pressure control (BPC) valveCondition* noneECM-6805 TURBOCHARGER (TC) CONTROL VALVE
PRESSURE TOO HIGH - PERMANENT/INTERMITTENT FAULTChecking the hoses and turbocharger (TC) control valveCheck that the hoses between the intake manifold, pressure regulator and turbocharger (TC) control valve are not trapped, blocked or damaged.Check the turbocharger (TC) control valve by activating it.Check the alignment of the boost pressure control (BPC) valve pressure servo and the boost pressure control (BPC) valve and that they are functioning correctly and not sticking according to See: Component Tests and General Diagnostics\Boost Pressure Regulator, Checking/AdjustingVerificationHint: After carrying out the repair, check that the fault has been remedied.* Ignition off.
* Reinstall connectors, components etc.
* Disconnect the VCT 2000 from the data link connector (DLC).
* Test drive the car and check that high boost pressure is obtained.
* Connect the VCT 2000 to the data link connector (DLC).NOTE: Do not switch off the ignition before the VCT 2000 has been connected and the boost pressure has been tested with the smart tool.Read the boost pressure fault status
When the boost pressure has been tested the display should show that the diagnostic is complete.
Customer: replied 1 month ago.
I, thanks for your reply. I have vacuum tested all the hoses and connections and they are all good. The boost pressure control valve I have tested and seems to be working fine. I have fitted a new turbocharger control valve as I took the old unit off to inspect it and found that the diaphragm had a split in it so fitted a brand new one, have you ever experienced a brand new part being faulty
If bought original volvo They ok most time no problem If You bought other brand They can be BAD new i seen IT
Send me part number i double check
Customer: replied 1 month ago.
It’s a pierberg part which is identical to the one I have taken off. The part number is *****
Puerberg is good
Problem can be with turbo overcontrolling it that can be tested using very expensive turbo test gauges not with buying for one time use I would run turbo test at Volvo garagr using scan tool and gauges
Customer: replied 1 month ago.
How should the wastegate/actuator arm move when revving the engine, mine moves twice when you let off the accelerator
Well under load IT moves best driving
Reving engine movement to move twice is good
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Customer: replied 1 month ago.
Could the turbo vanes have carbon build up or would the wastegate not move if that was the case. Could the egr be blocked. I just don’t know why it’s sending boost back up the air intake when you let off
Carbon build Up yes You correct but carbon can be build at turbo it self also egr is yes and no if is clogged to much can be effect other systems also
Turbo do Go BAD also on diesel They Wear out much faster and clogs up than gasoline petrol engine
Customer: replied 1 month ago.
tomorrow I should remove turbo and check for carbon build up
You can check
Enes and other Volvo Specialists are ready to help you
Customer: replied 1 month ago.
Hi, how can I test the egr solenoid. Will it need a full 12volts or will a 9volt battery be enough to move it
12 volt