S80: Engine Turbo Boost Pressure Solenoid 31293964

[TheBeast]

Thanks for your input Thassos.

Originally Posted by Thassos

Morning,, i had missed your drawing in post #5 (so much for speed reading!), would the pierburg part be item 12? and the vaccum actuator the round component below the turbo? with no number?

Correct.
Annoyingly, I believe with this car, I'd have to buy a whole new turbo+vacuum actuator if a part turns out to be faulty. But fingers crossed the fault lies elswhere.

To be fair, the car drives fine and seems to have enough power, so is very drivable.
Also, she just passed the MOT so emission wise (all this could be EGR related too according VIDA) all seems well...

Originally Posted by Thassos

Some questions & things to try..

A) you mention applying 12v (would suggest using a DVM to probe the 2 wires going to the pierburg 'solenoid' to see what polarity they are before applying 12v in same polarity. If you blow on the port when 12v applied, does it pass thru or close flow of air?

Tried to see if there is a difference between power on and off, but didn't feel any difference. This is just me blowing/sucking on an attached hose though. Will try it with a vacuum pump attached and see how that goes.

For polarity, I used a Youtube video of somebody showing a diagram of one, so hope that was a comparable item.

I will see if I can confirm the polarity the way you suggest.

Originally Posted by Thassos

B) Well worth getting a cheap chinese version of a mityvac, or maybe use a large syringe with tube and attach to the capsule to see if you can make the turbo actuator move with vaccum applied, sometimes you can freely move the arm or linkage with no tube attached, or get an idea of what resistance there is to moving the linkage incase its something internal to the turbo.

Great minds and all that... Just ordered a very cheap one this morning that should be sufficient for my purposes. I have no need for a fancy one, as I won't get enough use out of it.

Originally Posted by Thassos

C) You might also use the 'mityvac' attached in place of the capsule to see if any vaccum is getting applied via the 'solenoid' similarly with engine running, (again just ideas here..) Also see if the tubing run back from the capsule will hold a vaccum - incase of a split or poor / missing tube connection.

Will do.

Originally Posted by Thassos

Usually on pwm type connections one side is permanently (chassis, or +12v feed) and the other is switched on-off on a regular time loop that is giving the %age from fully open to fully closed. No idea if this applies here but with 2 wires to something there are only a limited number of ways it can work ! the signal will be coming from the ECU from one or both sides, might also be worth using a dvm to trace the wiring back to the ecu plug (just use a small bit of small guage wire to 'probe' the connector without pushing something oversize in it that might cause damage,..) incase its a broken electrical connection (prob less likely).

If you have a DVM, but not all will have this function, you need one that can show frequency or something like (may have PWM in its setting), you could attach this across the actuator (ie with it all plugged in), only easy way is with sharp probes, a bit of info below might be useful

https://www.fluke.com/en-gb/learn/bl...ure-duty-cycle

Anything to do with electrics is witchcraft to me, but I'll have a good go at it! How you do switch on a multimeter..?!?

Thanks for the link. I'll have a look.

Originally Posted by Thassos

You mention your engine is a T3? so is it a single turbo not twin? some info from wiki, below (cant believe how many versions there have been...)

https://en.wikipedia.org/wiki/Volvo_D5_engine

Yeah, madness how many versions there are… I believe it is a single turbo, yes. But currently have the heat shield still sitting above the turbo so con't confirm, but the diagram would imply so.

Thanks for your pointers.

[TheBeast]

Right. Here's an update.

I acquired a vacuum pump to check for leaks some more on all hoses (already did smoke tests) and found non.

I also checked for movement of the arm leading to the turbo when vacuum is applied to the hose. Clear and constant movement seen.

I've compared the old "switch/gate/turbo boost solenoid/Governor' (whatever the thing is called) with the vacuum pump and noticed a clear difference.
The 'new' one (=second hand) holds vacuum nicely and releases OK too when connected to 12V.
The original one does build up a vacuum OK but doesn't hold it for long, so probably faulty.

So, the above would imply it was a fault in the governor that possibly caused the fault codes to come up.

The strange thing is (to me anyway) that the same fault codes come back with the 'new' one, as it should 'do its thing' properly.

Apart from the multimeter tests (I'm useless at that and I do observe changing signals in VIDA, implying signals get to and from the governor OK) I've now checked, as far as I know, all possible causes.

Because of the above, I decided to run the 'Adaption turbo system' in VIDA.
It has done things to what it was set to before, and to what it is working to now.
I've attached the before and after values if they mean something to anyone.

What I noticed after running the adaptation is that the closed and 60% turbo position are now correct (it was sitting at ¬80% before, when commanded to be 60% (see post 7).
Oddly, when running on the 'Control returns to the control module', it gives around 50%. According to VIDA this should be 80% at idle...

Will keep an eye on it the next few days to see if it throws up the earlier underboost codes again...

[TheBeast]

Have done 500+ miles since the above post and all seems well. Just checked with VIDA and there are no turbo related messages stored.

So in conclusion, the governor might have been part of the problem, but simply replacing it did not solve the issue. Running the turbo adaptation was needed to get rid of the ever reoccurring fault codes.

Thanks to those that took the time to share their knowledge with me.

Cheers!

[hal9000f]

No need to start another thread, this one is very useful and interesting, so ...

V70 D3, MY 2013, engine D5204T7 with single VNT turbo, 160 tmiles.

The following DTC keeps reappearing, but the car drives fine, no noticeable problems.
Maybe lacks a bit of power for a fraction of a second sometimes when accelerating hard.

"ECM-P003A85 Turbocharger/Supercharger Boost Control a position exceeded learning limit..."

I know what the P/N 31293964 (VNT) Governor is (Actuator turbo pressure, Boost pressure control valve and all other names...), and I know the location.

But, where is the turbo position sensor located?

It is mentioned in the description of the ECM-P003A85 DTC as one of the three possible sources:

- The turbo position sensor does not show correct position.
- Vacuum hose for turbo control has cracked or come loose.
- The mechanism for angling the guide rails has jammed.

Is the turbo position sensor a standalone sensor, or is it integrated into turbocharger?

And what is "The mechanism for angling the guide rails"? Is it the VNT Governor or something else?

Thanks all.