SDV6 Slight miss when cruising, any ideas?

[Owen]

My SDV6 D4 MY2011 has picked up an intermittant miss when cruising at either 100 or 110 with the cruise control on that has tripped the restricted performance mode. The diagnostic indicated a presure issue however we cant find fault. Short of pulling apart the intake and cleaning it all, anyone have any suggestions?

[DiscoJeffster]

You need to get the faults out of it before we can help. You’ve got a leak I’m sure, and it’ll probably be the drivers (right) intake manifold. Common. I recently found the plastic y joint that feeds the two intake manifolds on mine had split causing restricted performance, however that’s not common.
Quickest fix is a smoke test to check for leaks. I made one up using a tin, mosquito coils, and an air compressor. Smoke from the burning coils worked perfectly. A bit backyard I admit but genuine smoke machines are expensive.

[LRD414]

As mentioned, there's a few possibilities. See this thread for another possible cause < Restricted Performance Event (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/253796-restricted-performance-event.html) >

The codes I had matched exactly with what others have reported when the issue was a sticky secondary turbo isolation valve (compressor shut-off valve), resolved by freeing-up the valve actuator shaft of dirt & grime. P1247-00 is boost pressure not achieved and P0235-94 is boost sensor unexpected operation. However there was nothing wrong with the actuator on mine and simply changing the intercooler/intake hose hose fixed the issue.

Cheers,
Scott

[DiscoJeffster]

Yep. Needle in an extremely large haystack without the fault codes

[BobD]

Mine was getting a low boost error randomly after replacing the manifolds and then months later the turbos. On our recent around Australia trip towing my KK it would randomly go into limp mode up the steep hills around Sydney and if I dropped down a couple of gears it would fix itself, thank goodness, since we were in heavy traffic and towing up hill.

We found the problem when we got back to Perth and apparently it was due to a couple of leaking rubber grommets in the manifold, or at least that is what I was told. After fixing that, it has not had an error since.

This is different to the Restricted Performance error you get with a split manifold (which was why I replaced the manifolds) and resets itself without stopping 99% of the time.