Vacuum Assisted Engine Mounts & Vacuum System Test
 

I've had the "ENGINE SERVICE REQUIRED" pop up on the display twice now so I decided to investigate a bit further. Using some software called TouchScan on my laptop and a Bluetooth ELM327 interface I read the error code, P0244- Wastegate control solenoid valve malfunction (Over Boost) was stored.

Searched the internet and found a few videos relating to the XC90's vacuum system by outnumbered(mike) on YouTube and decided to have a closer look.

I brought a Sealey VSE952 Vacuum Gauge and connected it to the vacuum system where the red arrow is pointing in the diagram.

http://i296.photobucket.com/albums/m...psbc749e3f.jpg

This was the result at tickover 2 weeks ago.
http://s296.photobucket.com/user/Sha...b4ad1.mp4.html

This was the result at tickover today with the engine mounts disconnected, a good vacuum reading I think.
http://s296.photobucket.com/user/Sha...f92e1.mp4.html

I then reconnected the engine mounts and got this. By pinching the pipe to the rear engine mount I could make the reading increase.
http://s296.photobucket.com/user/Sha...f0f80.mp4.html

My conclusion:
Either the engine mount or the pipe feeding it has a leak and this is why I've had the "ENGINE SERVICE REQUIRED" pop up and a loss of power.

Can someone confirm I'm right before I order a new rear engine mount and some pipe?

vid one depending where you have that gauge hooked into should show a vac at least 25hg on idle to the inport to the Tcv from the out port of the TCV you should have at idle 25hg pads on, above 1500 rpm no vac to out port of Tcv pads off.if there is a pad leak it can effect the vanes on the turbo and cause that code
mike

I had the gauge hooked up where the red arrow is in the diagram for all tests, on the vac side of the TCV. With the TCV and engine mounts completely disconnected I got 38/39hg. With the TCV and engine mounts reconnected I got 3.5hg until I pinched the pipes leading to the engine mounts. Pinching the pipe to the front engine mount made no difference, pinching the pipe to the rear engine mount caused the gauge to increase to 5/6hg.

Just done a couple more tests, no vids this time, had to be quick.

No TCV or engine mounts connected at 3000rpm I got a reading of 58hg.

Reconnected the TCV and engine mounts, gauge connected after the TCV(engine mount side) at tickover I got 10hg this time. Soon as the revs hit 1000rpm the gauge dropped to 2hg and stayed there right the way up to 3000rpm.

The TCV was hot to touch after only a few minutes of the engine running, surely that's not right?

So in conclusion, the car has a slight leak on the rear engine mount(or its pipe) and a faulty TCV?

The Tcv will get hot.

mike

So the TCV is ok, it getting hot is not a problem? Might replace it anyway.

Would I be right in saying the problem(leak) is definitely after the TCV, engine mount or related pipework? Solution, replace pipework(cheapest option) if problem persists replace rear engine mount?

EDIT.
What internal diameter pipe is used, 4mm ?

Right, this is what happened.

The wife decides to drop a surprise trip to Cheddar Gorge on me, had to think quick.

She's a nurse and half the Vacuum System was leaking, SO, this is what I did. Check this out .. :thumbs_up:
http://i296.photobucket.com/albums/m...ps9744d4ab.jpg

With the engine pads "pinched off" the car performed brilliantly, an absolutely faultless 600 mile round trip.

Here she is enjoying the sun in Cheddar Gorge.
http://i296.photobucket.com/albums/m...ps14078305.jpg

New vacuum pipe was delivered this morning.
3 meters of black 3mm silicone vacuum pipe and 3 meters of black 4mm silicone vacuum pipe for £14.

Going to replace all the vacuum system pipes. Most of it seems pretty straight forward except the rear engine mount/pad. Whats the easiest way to gain access to it?

At that age it's more likely to be the rear engine mount that's leaking I would have thought.

Just had mine done. Labour £124.20 Engine Mount £89 Plus VAT. It wasn't generating a fault code but the engine had dropped by about 25mm.

Did you need both 3 and 4mm hose?

I purchased 4mm to use between the vacuum pump and where it T's and separates. One side feeds the engine mounts/pads the other side feeds the turbo actuator, I did both of those in 3mm. I suppose I could have done it all in 3mm or even in 4mm but I wanted to keep the size quite small so it reduced the amount of air the vacuum pump had to remove from the system to maintain a good vacuum. Seems to have worked as the car responds to the throttle better now, especially from a stand still.