3.0l Turbo malfunction

[Ferret]

I have been off the road for 2 weeks with a turbo problem that has turned out to be a bit unusual so I thought I might provide a bit of an write up.

Took the D4 to the dealer for a routine service. On picking up and driving home got to within about 500m of the driveway and bang - a muffled backfire sound, bit of a jolt then 'restricted performance' message, a big red triangle and an orange engine light up on the dash.

Rolled in to the driveway switch off and up with the bonnet. Engine would start and rev OK but it sounded like there was a bucket of bolts circulating around inside something on the drivers side of the engine as it idled down. Bugger - turbo I thought.

LandRover assist to the rescue and the next day the dealers rings to tell me the compressor shut off valve (aka turbo isolation valve) is the culprit. These are known to have a habit of jamming up.

A new isolation valve was fitted but with no change to the engine symptoms. So more head scratching and it was decided the turbo actuator was at fault. First the actuator arm was swapped out and when that changed nothing the entire actuator as changed. Again no positive result.

At this stage I'm glad I'm not paying for anything and the dealer conceded defeat. Diagnostic logs were sent to LandRover for further analysis. Eventually the fault was traced to the failure of small vacuum operated switch associated with the operation of the turbo isolation valve. Dealer reckons they have never seen a failure like it before.

So before complicated actions after apparent turbo failure, particularly failure pointing to the turbo isolation valve, might be worth while checking the operation of this little unit first.

https://www.aulro.com/afvb/attachments/l319-discovery-3-and-4-a/133786d1513772646-secondary-turbo-problem-potential-p1020588.jpg

https://www.aulro.com/afvb/attachments/l319-discovery-3-and-4-a/133787d1513772707-secondary-turbo-problem-potential-p1020589.jpg

[discotwinturbo]

Peter,

So is she all good now ?

Amazing that with modern diagnostics that a faulty part can't be pinpointed first time around.

Brett...

[BobD]

It sounds like the diagnostics pin pointed the actual failure but not that it was caused by the control switch. Interesting that it occurred straight after a service. It has happened to me in many different vehicles, especially my BMW motorcycle, that bad things always happen straight after a service that did not go anywhere near the offending part. Its either Murphie's Law or the mechanics are doing stuff that we don't know about.

Bob

[Ferret]

So is she all good now ?

Yeah, all's good and good to know it was not the turbo itself given the stories others here have told.

Rob (you know who) reckoned the diagnostics just weren't leading them there. I think there is a bulletin issued for the compressor isolation valve jamming so I think they were focused on following through on the testing and diagnostics that was telling them to perform rather than looking further a field. The valve was non operational but not because it was jammed, just behaving like it was.



... bad things always happen straight after a service that did not go anywhere near the offending part. Its either Murphie's Law or the mechanics are doing stuff that we don't know about.

Tell me about it. Last 2 out 3 routine services the dealer has provided me has ended in limp mode and a tilt tray ride within ~25 km of leaving them. To their credit this time, they had me in a loan car by the 3rd day, but still ...

[Graeme]

There is a quick test procedure used to determine if the valve is sticking. It involves temporarily removing then refitting the vacuum hose to that solenoid but with certain time delays. It seems that the dealer didn't do the test which would have revealed that the solenoid was faulty and would have prevented all the other work and unnecessary delay.

Edit: It seems that the test was done but the lack of vacuum at the solenoid wasn't detected nor was the valve checked for sticking once removed.

[Ferret]

... nor was the valve checked for sticking once removed.

Yeah, that occurred to me also once the real fault was identified.

[Graeme]

I suppose that if the valve can stick for reasons other than the external dirt that caused mine to stick then there could be a case to replace it anyway. Hopefully the replacement has the external fittings redesigned to prevent jamming from dirt so that at least you have some benefit from being without the vehicle for so long. Mine however will again stick unless something gets changed.

[v8sruleok]

Yeah, all's good and good to know it was not the turbo itself given the stories others here have told.

Rob (you know who) reckoned the diagnostics just weren't leading them there. I think there is a bulletin issued for the compressor isolation valve jamming so I think they were focused on following through on the testing and diagnostics that was telling them to perform rather than looking further a field. The valve was non operational but not because it was jammed, just behaving like it was.




Tell me about it. Last 2 out 3 routine services the dealer has provided me has ended in limp mode and a tilt tray ride within ~25 km of leaving them. To their credit this time, they had me in a loan car by the 3rd day, but still ...

Hi Ferret,

I realise that it's been nearly 6 years since this thread was last active.

I have just been googling D4 shut off valve because I'm thinking this could be one of the issues affecting my car.

I was interested to see that your pictures and my own diagnostics seem to arrive at the same point, but the problem is that I'm just not sure of the circumstances that would open the TSOV. I climbed underneath the vehicle and had a good view of the actuator arm then asked the missus to rev the engine to 3K. The test was repeated a few times at varying revs and the actuator arm did not move at all.....though I can operate it manually so it's not seized. I took the vacuum line off and there was no suction at all. I traced the line back to the area in your pic and pulled the hose off at the solenoid and still could not get a vacuum response.

Do u know what sort of rev range/or other circumstance will open the TSOV as I may not be achieving the criteria for the solenoid to activate vacuum to this line?

Thanks, Mike.

[Ferret]

Do u know what sort of rev range/or other circumstance will open the TSOV as I may not be achieving the criteria for the solenoid to activate vacuum to this line?

Sorry, can't really help you with that one, don't know enough about such things.

Just as bit of an experiment I did connect my GAP tool and set it up to measure and view the air flow from both MAFs thinking this should say something about whether the TSOV is open or closed.

Just sitting in the drive way and slowing revving the engine up to 3k you can see the air flow in one MAF increase with revs but the other MAF stays flat. But remember this is under no load conditions in the drive way.

On the other hand, stabbing the accelerator from almost any base rpm, you get both MAFs to respond in some way. Typically air flow from one goes up while air flow from the other goes down relative to each MAFs base level air flow at the base rpm.

[v8sruleok]

Sorry, can't really help you with that one, don't know enough about such things.

Just as bit of an experiment I did connect my GAP tool and set it up to measure and view the air flow from both MAFs thinking this should say something about whether the TSOV is open or closed.

Just sitting in the drive way and slowing revving the engine up to 3k you can see the air flow in one MAF increase with revs but the other MAF stays flat. But remember this is under no load conditions in the drive way.

On the other hand, stabbing the accelerator from almost any base rpm, you get both MAFs to respond in some way. Typically air flow from one goes up while air flow from the other goes down relative to each MAFs base level air flow at the base rpm.

Hi Ferret,

Thanks for reply. Today I did some live data on my IID. I found you can select compressor shut of valve, and compressor recirculation valve as options, which is what I did and now I know that they are working. Tks for yr orig post, it was an interesting read. Cheers.

[Eric SDV6SE]

Hi Ferret,

I realise that it's been nearly 6 years since this thread was last active.

I have just been googling D4 shut off valve because I'm thinking this could be one of the issues affecting my car.

I was interested to see that your pictures and my own diagnostics seem to arrive at the same point, but the problem is that I'm just not sure of the circumstances that would open the TSOV. I climbed underneath the vehicle and had a good view of the actuator arm then asked the missus to rev the engine to 3K. The test was repeated a few times at varying revs and the actuator arm did not move at all.....though I can operate it manually so it's not seized. I took the vacuum line off and there was no suction at all. I traced the line back to the area in your pic and pulled the hose off at the solenoid and still could not get a vacuum response.

Do u know what sort of rev range/or other circumstance will open the TSOV as I may not be achieving the criteria for the solenoid to activate vacuum to this line?

Thanks, Mike.

on the sequential turbo 3.0l, the vacuum solenoid operates even at idle speed. If you let the car idle for a few minutes you’ll hear the exhaust note change as the vacuum solenoid opens the air valve and the second turbo is spooled up, this is to ensure the second turbo gets enough oil and is cooled.

My experience was similar, at 120,000km (about 3 years ago)I got the restricted performance triangle, original diagnosis was the solenoid, this was replaced under warranty. Still the same fault, next the diagnosis was the primary turbo, also replaced under warranty, then finally the air control valve also under warranty. No further issues to date.

[DiscoJeffster]

Hey Eric. In all my time I’ve understood turbo oil bearings flow whether spinning or not through oil pressure alone. Did you read that somewhere in the manual? I’d have said it moves as part of the start up testing cycle rather than through a need to cool the turbo.

[Eric SDV6SE]

Hey DJ, this where I got that info from. See the text above the exclamation mark.

https://www.aulro.com/afvb/blob:https://www.aulro.com/b831d994-8151-44e5-a4ac-3a5ded26ff71




You are correct that the turbo bearings are force lubricated from engine oil pump pressure. To my mind this lubrication is also part of cooling the turbo.

[DiscoJeffster]

Wicked dude. Thanks. Interesting stuff!

[LRD414]

The WSM statement mentions cycling the turbine shut-off valve during idling but not the compressor shut-off valve, which is the one that typically sticks.

Scott

[DiscoJeffster]

The WSM statement mentions cycling the turbine shut-off valve during idling but not the compressor shut-off valve, which is the one that typically sticks.

Scott

Rereading it, good point.