Turbo Boost sensor

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doctle
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Turbo Boost sensor

Post by doctle »

Hi guys
Started the car this morning and got a new anti pollution warning. Scan said P0238 turbo boost sensor. There is one on the manifold but no wires going to it and doesnt seem to be any wires for it. I assume it's the sensor at the top left of the air filter. Does anyone have a diagram or some info? Car is booked in for test in the morning clearing the code only works for a minute. VF3**************[VIN obfuscated, can be read by forum staff]
Thanks
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Re: Turbo Boost sensor

Post by MikeT »

Do you have all the captured data from the fault code? It's quite a generic code based on readings from the MAP sensor.
I don't know the layout of your engine, but it will be downstream of the turbo (so it can measure turbo boost) whereas I think the sensor you located near the air filter (which is upstream of the turbo) wll be the MAF.
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Re: Turbo Boost sensor

Post by GiveMeABreak »

From what I can see this engine doesn't have a solenoid for the turbo boost - it uses a mechanical vacuum capsule. So I would check you are getting enough vacuum from this.
207 Air Circuit.PNG
ReferenceDesignation
1injection ECU
2Recycling regulation electrovalve (EGR)
3vacuum pump
4Exhaust gas recycling valve (EGR)
5Air inlet manifold
6Exhaust gas manifold
7Boost pressure waste gate : Pressure-controlled
8Pneumatic control capsule for the waste gate (on turbocharger) : Pressure-controlled
9Catalytic converter
10Exhaust turbine
11turbocharger
12Air inlet turbine
13Air flow meter + Air temperature sensor
14Air cleaner
15atmospheric pressure sensor (integrated in the injection ECU)
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Re: Turbo Boost sensor

Post by GiveMeABreak »

Some more info on operation:
207 Turbo A.PNG
207 Turbo B.PNG
(7) Boost pressure waste gate.
(8) Pneumatic control capsule for the waste gate: Pressure-controlled.
(10) Exhaust turbine.
" a": Pressurised oil delivery (evacuation of gases and cooling).
" b": Oil return.
(7) Boost pressure waste gate.
(8) Pneumatic control capsule for the waste gate : Pressure-controlled.
(10) Exhaust turbine.
(12) Air inlet turbine.
" c": To the inlet manifold.
" d": Gas from the exhaust manifold.
The turbocharger consists of two separate chambers.
The turbocharger consists of the following components:
  • A chamber connected to the engine exhaust function
  • A chamber connected to the inlet function
  • A turbine and a compressor, connected by a shaft
The turbocharge pressure is regulated by the waste gate valve.
At rest the waste gate is closed.
The boost pressure is regulated according to the air pressure in the inlet manifold.

Operating phases once the pressure value of the pneumatic capsule ( 8) has been exceeded:
  • The boost pressure waste gate opens
  • The exhaust turbine speed decreases
  • The boost air pressure decreases
  • The decrease in the boost pressure causes the boost pressure waste gate to close.
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doctle
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Re: Turbo Boost sensor

Post by doctle »

Thank you I will have a look when it stops raining. When I delete the code and rescan it's still there before I start the engine.
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Re: Turbo Boost sensor

Post by MikeT »

Looks like old school fixed vane turbo wastegate setup. It's activated by pressure, not vacuum.
Anything on the boost pressure sensor itself, Marc?
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Re: Turbo Boost sensor

Post by GiveMeABreak »

It refers to the Air Pressure sensor as I mentioned above:
207 Air Pressure Sensor.PNG
The turbocharge pressure is regulated by the waste gate valve.
At rest the waste gate is closed.
The boost pressure is regulated according to the air pressure in the inlet manifold.

Operating phases once the pressure value of the pneumatic capsule ( 8) has been exceeded :
The boost pressure waste gate opens
The exhaust turbine speed decreases
The boost air pressure decreases
The decrease in the boost pressure causes the boost pressure waste gate to close.
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doctle
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Re: Turbo Boost sensor

Post by doctle »

There is no plug that goes to 12 sensor on my car could this be the problem?
Thanks
Paul
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Re: Turbo Boost sensor

Post by GiveMeABreak »

There should be the measuring pipe (13) on the diagram, and also an electrical connector. This diagram is from your VIN, so the sensor will be doing diddly without an electrical connection and that will throw the engine ECU in to compensating and giving you the issues I suspect.

Have a good check around there to see if it has been disconnected accidentally (or otherwise). It may have been taken off during some other maintenance and forgotten to be reconnected - it happens - even by the dealers!
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Re: Turbo Boost sensor

Post by MikeT »

doctle wrote: 05 Feb 2019, 11:17 There is no plug that goes to 12 sensor on my car could this be the problem?
Thanks
Paul


Is #12 the sensor you referred to by the air filter? If so, I stand corrected and think #10 is the MAF.
And yes, if it's not connected, it most likely is the cause of the fault.
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Re: Turbo Boost sensor

Post by MikeT »

GiveMeABreak wrote: 05 Feb 2019, 11:14 It refers to the Air Pressure sensor as I mentioned above:
The boost pressure is regulated according to the air pressure in the inlet manifold.


I think we're at cross-purposes here, Marc... The only "boost control" affected is from manifold air pressure acting direcltly on the wastegate, which simply bleeds off exhaust gas once a certain pressure is reached.
In this instance, the MAP plays no part in controlling boost. It just reports the pressure to the ECU (presumably for fuelling and DTC purposes).
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Re: Turbo Boost sensor

Post by GiveMeABreak »

(10) is the MAF, (12) is the Intake Air Pressure Sensor (manifold), but the turbocharger pressure is regulated by the waste gate valve.
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doctle
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Re: Turbo Boost sensor

Post by doctle »

GiveMeABreak wrote: 05 Feb 2019, 11:26 There should be the measuring pipe (13) on the diagram, and also an electrical connector. This diagram is from your VIN, so the sensor will be doing diddly without an electrical connection and that will throw the engine ECU in to compensating and giving you the issues I suspect.

Have a good check around there to see if it has been disconnected accidentally (or otherwise). It may have been taken off during some other maintenance and forgotten to be reconnected - it happens - even by the dealers!

I suspect I may have tucked the wire somewhere "safe" when I changed the injector seals. The air filter housing is a tight fit. I will go hunting if the rain stops if not I will have to make a tent from tarpaulin I will report back, thanks guys
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Re: Turbo Boost sensor

Post by GiveMeABreak »

Yes, let us know - it all helps and sometimes it is the simplest of fixes :-D
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doctle
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Re: Turbo Boost sensor

Post by doctle »

The wires for the manifold sensor had fallen behind the EGR pipes looked like they were supposed to be there. I had to clamp a tarpaulin on to the bonnet crude but it kept me dry. I told the wife I had left a wire off she said "you're very stupid" not much sympathy there.
Thanks to ll you guys you're always quick to reply and a font of information Much Appreciated
Paul
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