Another Restricted Performance thread

[ghoti]

Hi all,

Towing a ~2 Tonne boat on holidays when an hour from home we get the dreaded red triangle and Restricted Performance message. Car could maintain 100kmh, except up hills, and acceleration was "restricted". Decided to continue on to fuel stop around 30km away. Refuelled, started and warning was gone...only to return another 50km down the road.

Pushed on for 100km and stopped for lunch. After lunch, all clear for another 30 to 40km, then got both restricted performance message and check engine light. RACV app reported code P006a. Kept stopping and resetting, travelling 300km overall from first warning.

Arrived at destination and searched forum, leading me to fear potential throttle body issue. Planned to do ECU reset next morning.

Next morning car started, no issues reported. Took for a drive (aka "italian tune up" as mentioned in one of the posts) and all good. Hooked up boat and went for a short trip, all good.

Is it likely to have resolved itself, or is it more likely to be a major problem that will reoccur on the trip home?

Thanks.

[DiscoJeffster]

I’m the expert on the topic, having had nearly every holiday trip ruined by it, whether it be intake manifold or throttle body.
The error is real but in a lot of cases when the leak is small, it will only show when there is sustained load and thus loss of air.
Throttle body is a common failure as the plastic splits between the Y and the throttle mechanism. Superglue fixed mine for 5000km and then it failed again and I replaced it.
This weekend I’m replacing my passenger side manifold. It’s now grown to a 3 inch split and the cars practically undrivable now, and has gone to engine light and restricted performance triangle. Oops.
Also known for intercooler pipes to split, more common on the 2.7L I believe.
Sometimes you’ll get restricted performance for other faults but P006a implies an air leak.

Get a smoke test done, or even easier, place some white paper across the manifolds and the throttle body and go for a drive. You’ll soon find the leak as you’ll have a black piece of paper.

[LRD414]

.... whether it be intake manifold or throttle body ....
There are other causes of the Restricted Performance alarm, two of which I have experienced:
- secondary turbo isolation valve sticking
- secondary turbo actuation solenoid faulty
- inlet hose distorted/split

These threads have some details.
Restricted Performance Event (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/253796-restricted-performance-event.html)
Sticky primary turbo actuator - external fix? (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/176368-sticky-primary-turbo-actuator-external-fix.html)

Cheers,
Scott

[Eric SDV6SE]

I'll add one more to that list - throttle body o-ring ( where it meets the plenum) has failed. Mine popped at 180,000km. Part cost $13 labour cost $300....

The restricted performance code and car behaviour sounds very free similar to mine.

[ghoti]

Thanks all. Drove home with boat in tow and restricted performance displayed for 99% of the trip...roughly 350km. On the flat 110kmh no problems, but the slightest hill saw a dramatic drop in roadspeed.

Will try the paper test tonight if I can leave work early.

[101RRS]

What I have previously posted on this on a few different forums. Are my thoughts.

My 2.7 suffers the same.

It would seem to be basically an ECU programming fault in the software and the fault shows up when inlet manifold pressures are different to what the ECU is expecting - response from the car is either shut down, limp mode, nothing but the engine light comes on.

See if this is a similar scenario to what you have.

Drive the car around every day - car might be loaded up - use a bit of throttle - make the car work but no issues like you describe (manifolds pressures are what the ECU expects).

Now connect up your caravan (I have a campervan) and drive it sedately - no full throttle, no real big hills and nothing happens.

Now head up a big hill, use a lot of throttle maybe flat to the floor so the engine is really loaded up and the issue pops up (manifold pressure is not what the ECU expects)

Maybe straight and level towing that van and sitting on your 60mph just idling along on a secondary road - a slowish vehicle ahead and you go to overtake but that oncoming car is still a safe distance but a bit closer than expected - foot to the floor to use those horses and the gong gong gong the fault light is on - pull over switch off and on and all good most likely no codes. I have learnt how on the freeway to switch into neutral, switch the engine off and back on before you loose steering and brakes and continue on my way.

Even when towing but not using a lot of throttle the problem does not occur. Lots of throttle creating high engine loads because of the 2 tons you are towing and gong gong gong.

It is if when they wrote the computer software they wrote it to suit the car without a requirement to tow anything.

So if at all possible when towing I just try not to get into positions where the throttle needs to go to the floor - often easier said than done. Mine is a 2.7, plenty of people report it in 3.0s and TDV8s BUT not any of the petrol V8s.

Garry