Restricted Performance Event

The 2nd turbo in the main won't be used if the engine doesn't have enough load, regardless of engine revs. However there is a test procedure for the solenoid+valve that involves raising the revs above idle to around 1200 rpm IIRC but possibly considerably higher, disconnecting the CSOV's vacuum hose from the solenoid for several seconds which should affect the revs if OK, then reconnecting the hose to cause the revs to go back but I can't recall whether the revs should increase or decrease with the hose disconnected. However if such a test was tried which resulted in the revs changing then going back then I would consider that the solenoid+valve are working.

It is possible that the test is only for the solenoid and that the engine revs change if the reduced vacuum in the vacuum system causes some other change such as the air/fuel mixture due to another component changing its setting, but my recollection is that the procedure was to test both the solenoid and the CSOV when so many early 3.0 D4s were having problems with the valve.

Edit: I've only now discovered that a repair kit LR033284 is (or was) available to replace the linkage arm and vacuum chamber of earlier valves with the later design linkage and vacuum chamber.

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Originally Posted by Ossieh20

....When I tested/viewed mine it stayed closed until accelerator was released above 3000 rpm and then it opened fast and then closed again also when reved short and sharp similar operation .....

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This is exactly what I found when testing mine looking for any performance issue with the valve.

Scott

Hi Guys, built my own smoke machine this morning and couldn’t detect any leaks. Still playing around with the electric vacuum solenoid, disconnected it while running and reconnected then solenoid does not function. Took it for a drive and the performance was similar to how it has been lately without restricted performance. Reset fault code and solenoid is back functioning but only as an open close devise when reved and did not open vacuum actuator when loaded in gear and accelerated with foot on brake. Eng management restricts rpm when you try this so solenoid did not open. Will try and swap out with mates this avo.
Thanks again for the feedback, I’ll keep ticking items off before it goes to eastern rover in Kilsyth on Tue. Hope I can sort it before the $$$$🚶🏻*♂️🤞.
oskar

I know you said all hoses checked out ok but my top hose looked ok too with the engine off and when idling. It distorted a lot when under proper loaded use. Perhaps replace it to eliminate as a cause given that it’s relatively cheap and easy?

Cheers,
Scott

No joy this avo, mate wasn’t happy with using his electric vacuum solenoid to test on my car. Will bench test it on Monday. His D4 operated the same as mine so still not sure what the root cause is. Economy is really bad now13.5 lt/100km used to be max 11 with the roof topper on and low 10 without around town. Will update when we find the solution...

Thanks Scott actually replaced my top hose last yr about this time as it split and the fault codes were different than I have now, did check it again but looks OK. As Graeme suggested I've looked deeper into the electric vacuum solenoid and the comment on PWM. I tested this solenoid on the bench and it is just a simple open close device so if you apply a PWM signal to the solenoid it would simply open and close quickly there by maybe slowly increasing the amount of vacuum to the bypass value hence slowly open, but the vacuum is being released by some other method/device in the system. If you apply vacuum to the bypass valve the actuator pulls and holds, some other device in the valley under the throttle bodies must release the vacuum. I connected a vacuum gauge to the line going to the bypass valve and connected an LED to the 12v connector to see if there is any pulsing of 12 volt during a drive cycle and I could not detect anything. Below is a link the youtube video I made this evening. Hope it might help someone.


YouTube

Update: vehicle reviewed by Eastern Ranges in Kilsyth vic, they checked vacuum hoses and general functions and swapped the pressure sensor monitoring the 2 nd turbo with a used sensor, cleared codes and road tested with no codes. I have done 40 km test drive through light traffic suburban streets and freeway and no codes and fuel economy was a respectable 8.9 lts/100km on cluster without rooftopper. Looks like this sensor is the issue. This sensor is located on the front of the rh bank screwed to the timing case cover and connected to a rubber hose that feeds off the secondary turbo. Will continue to monitor. Eastern Ranges said they have never had to replace this sensor before so something new for them.

I vaguely recall seeing the sensor but didn't know its function.
Great that the problem appears resolved and at a lot lower cost than fitting a new inlet manifold.

So often I see these posts and a week later it’s back. I hope it’s not but I think it’s too soon to crow success.

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Originally Posted by Ossieh20

This sensor is located on the front of the rh bank screwed to the timing case cover and connected to a rubber hose that feeds off the secondary turbo. Will continue to monitor. Eastern Ranges said they have never had to replace this sensor before so something new for them.

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From that i understand the "sensor" that is being referred to is the secondary turbocharger vacuum solenoid. There are two, one for the primary turbo as well.These are known to fail and cause these sort of fault codes.

I am not aware of any other sensor that is connected to rubber vac hose.

Glad it has checked out ok and that your indie was able to diagnose and fix correctly. Note the secondary turbo only activates at 2500rpm engine speed so youll have to take the car on a fwy run for an" italian tune up" to get it to spool up properly and ensure the solenoid is working ok.