Berlingo 2.0 - No Turbo Boost

[cancunia]

Does anyone know how the 2.0HDi turbo boost is controlled? I think there's a pressure valve that limits the boost by actuating the waste gate but I'm not sure how the boost is controlled other than that?
The reason for asking is that I have no boost or perhaps just the odd flicker and I'm wondering if there's a damp connection somewhere but I have no idea where to start looking. My OBD reader & Torque show no codes and also no boost.

Thanks

[GiveMeABreak]

VIN would help as different engines have different systems.

[cancunia]

AFAIK it's VF7**************[VIN obfuscated, can be read by forum staff]

[Michel]

Either a failed boost solenoid or a split vacuum pipe from it to the turbo.

[cancunia]

Either a failed boost solenoid or a split vacuum pipe from it to the turbo.

Yeah, I was wondering about that, but really have no knowledge about where such things are located for this engine. There's a vacuum pump that operates the EGR & brakes, but not sure if the vacuum pipe has another tee further on for the turbo or if / where there's another solenoid valve for the turbo..

[GiveMeABreak]

Here's the Turbo air piping for you to identify and check:

[cancunia]

Thanks, I'll follow those pipes. Any idea how it's actuated or the boost measured?

[GiveMeABreak]

They list running a pressure check using a gauge attached here:

[Michel]

Either a failed boost solenoid or a split vacuum pipe from it to the turbo.

Yeah, I was wondering about that, but really have no knowledge about where such things are located for this engine. There's a vacuum pump that operates the EGR & brakes, but not sure if the vacuum pipe has another tee further on for the turbo or if / where there's another solenoid valve for the turbo..

From memory if you follow the vac pipe from the EGR, it will lead you to the solenoid. I can't remember if it's the same shared two-outlet solenoid that operates both the EGR and Turbo or there are two. I think it/they are mounted under the battery on the inner wing..

[RichardW]

Looks like 2 solenoids - your location sounds about right.

[cancunia]

OK, it runs a lot better without the MAF! I unplugged it this morning before going out and it's like night & day, so I have a dodgy MAF. I'll try cleaning it, but wondered if anyone just leaves theirs disconnected?

I did some more reading about the turbo and exchanged a couple of emails with Steve at HDI Tuning. Seems that the turbo on the 2.0 HDi does not have any variable boost, it just spins up and opens the waste gate at about 14psi via a pressure valve. There's no boost monitor either AFAIK, it uses the MAF to calculate boost & EGR.

[GiveMeABreak]

I wouldn't leave it off TBH as the injection ECU uses the air flow rate to determine the correct amount of fuel to inject - air changes density with pressure and temperature therefore this will have a direct bearing on your fuel usage. On a diesel, data from the MAF is also used to control the EGR settings, and although you don't have a variable turbo, it may still affect the operation.

[cancunia]

Righto, does anyone have good / bad experiences of a particular brand of MAF? Prices vary enormously.

Thanks

[GiveMeABreak]

You need part number: 1920 7S. These are about £169 inc. from Citroen - and you need one with an outer diameter of 70mm.
There are a load here:
https://www.onlinecarparts.co.uk/oenumb ... .html?pg=1

Obviously, the better quality the more expensive they are.