Thread: Another 'Restricted Performance' post

" Air leak on plastic tube" do you mean the intercooler hose? Check all intercooler hoses and clips, noting that under no or low boost pressure it wont show up a leak. Perhaps remove and refit, cleaning as you go to ensure a good seal.

Also check the o ring that seals the intake to the throttle body, these fail and cause RP faults that you describe. It normally seals at idle and low engine rpm/boost pressure (when doing smoke test) but under higher loads can dislodge and cause boost pressure loss resulting in MAF errors and RP events.

Re turbo, Try freeing up the actuator and lubricating the pivot. Getting access to the actuator drive is a PITA but maybe getting some silicobe spray in there xoyld help rhe servo motor and gear move more freely.


You say SDV6, so im assumibg the 3.0L sequential turbo engine. The air control valve between the primary and secondary can also stick, this one is relatively easy to access from underneath the front drivers side, remove and clean the actuator may also help.

Cheers

Hi Eric,

Thanks for reply,

Originally Posted by Eric SDV6SE

" Air leak on plastic tube" do you mean the intercooler hose?

No, its a small vacuum line I think, continues from a 'T' piece near right wheel and runs up the body to join the vacuum supply near top of motor.

The rest of the things u said I will start investigating this weekend. To be honest, I did have my doubts that the smoke I pumped into the motor wouldn't be under enough pressure to reveal all possibilities.

Cheers.

Originally Posted by v8sruleok

....its a small vacuum line I think, continues from a 'T' piece near right wheel and runs up the body to join the vacuum supply near top of motor.

That could be the vacuum line to the solenoid that operates the secondary turbo isolation valve, which is the same valve that can be "sticky" for the 3.0L engine.

Restricted Performance Event

Scott

Thanks Scott,

I believe that you may be right regarding this vacuum line. I'll have another look over the weekend to confirm. Looks like the damaged section of my vacuum line has been melted through, though I haven't identified the possible source of the heat that did it.

I've previously read the post linked below, but re-reading with interest. It's a slow process working through the variables but hopefully I'll hit the jackpot soon.
Thought is was the damaged vac line as the car immediately responded with full performance and no errors (something not seen in months) but unfortunately on the next drive it was back in 'restricted' again.

Cheers.

Originally Posted by LRD414

That could be the vacuum line to the solenoid that operates the secondary turbo isolation valve, which is the same valve that can be "sticky" for the 3.0L engine.

Restricted Performance Event

Scott

I just thought I would come back & wrap this post up as the problem seems to have been resolved.

I gave up trying to fix this myself & put it in the hands of the pros. After much investigation around the routine stuff, the intercooler was removed and a small air leak was detected. A new intercooler was sourced & installed last week.

So far, after travelling 500km towing a 3T van in the south-west of WA I have had no faults arise. Fingers crossed.....we’ve got a lot of kilometres ahead as we’ve now started a 4 month road trip. Hopefully, these Disco woes of the past 11 months are behind us.

Intercoolers are another common failure. A mate who owns a low km 2013 recently had one go too, and I’ve seen other mentions. They’re not as common as the manifolds though which are a ticking time bomb

2011 SDV6 105000km on the clock, I had the restricted performance come up last Friday morning. Tried cleaning MAF's....that didn't work It turned out to be one of the three black nylon tubes that runs over the top of the engine and disappear down the left hand side between the fire wall and engine. One was rubbing against some electrical conduit. It was a a hard nylon vacuum line that I believe actuated turbo waste gate. Chopped out the section with the hole and pushed vacuum hose over both end to join, and the light was gone. I'd hate to have to replace one of these, mechanic mate told me he spent nearly a day to replace one tube.
I was lucky I could hear hissing coming from the nylon tube in the engine bay whilst engine was on, but it was still very hard to find, recommend a torch, for visual inspection and run you hands over the lines to feel for any holes, smoke might be a bit hard to use as the cooling fan on the engine creates so much wash. There is also a T-piece i am looking to replace as it is also rubbing through this is towards the front of the engine and probably the next to go.
Hope this helps......I will try to get a photo later.

Thanks for the post. I've spent considerable time on the engine with the main cover off just checking the routing and interfacing between all the various hoses and tubing. Ive tried to secure where I can whilst giving enough play to not bend or kink hoses. Zip ties are one of the best inventions ever. One hose I've found loose or problematic is directly under the throttle body. It is an air tube and has a non return in line valve in it. Valve works ok, but the ends of the valve that push into the hose are smooth, not barbed. With a bit of oil in the air lines, the smooth ends of the NRV can't grip the tube anymore. I've zip tied both ends of the rubber tubing over the fittings, no more leaks.