Thread: Restricted Performance Event

Struggling to find a solution to the restricted performance fault code hoping for some direction before taking to mechanic RRS 2012 3lt 180 kw 600Nm. Issue has progressively got worst over the last 4 months now get fault code every drive. Codes fault order p00cf, no restricted performance followed by p0235(0) and then p0235(94) restricted performance comes up on the dash and power is significantly reduced, keep driving and warning light goes away and performance returns. Economy has got about 20% worst.
Using car scanner elm, the proper LR scanner autologic only sees the same codes but does give more info about what to look for but I think the scanner I’m using is ok.
Turbo Pressure is measured at intake manifold, I bought new sensor but issue is the same and same codes came up.
Hoses that I can see and feel seem ok, a simple load test that LR mechanic did he said indicated turbo hoses and bypass valves seemed ok. Have not checked all vacuum hoses but the secondary bypass valve vacuum actuator works I need to check the egr vacuum hose and actuator but not sure when they should open. I’ve googled, forumed, and YouTubed the xxxx out of this error and checked everything people suggested but codes still get thrown up. Removed cleaned and tested 2 ndary turbo bypass valve as per Graeme’s suggestion no joy there either. Checked primary turbo actuator and works same as mates D4. Any suggestions would be greatly appreciated.

Firstly, can you confirm that the change-over valve's vacuum chamber arm connects to the valve by sitting on a stud rather than held with a nut? I'm pretty sure that your vehicle would already have the revised valve as the same sticky linkage occurred with the 4.4 TDV8 and my April 12 build 4.4 has the later valve.

The solenoid valve that controls the vacuum to the change-over valve can become sticky. Originally just a new solenoid could be purchased but the part number supersedes to the solenoid and most of the engine's vacuum tubes so is considerably more expensive. Can you temporarily swap the solenoid with the one from your mate's D4? Follow the vacuum tube from the valve up the front of the engine to the solenoid just at the top.

Hi Greame, thanks for the suggestions, yes I can confirm the vacuum actuator linkage is the later version stud not held by a nut and is all operating freely, removed cleaned and lubricated both vacuum and electrical solenoids on bypass valve. Just removed solenoid that supplies vacuum to the actuator and bench tested and all looks ok action of open close is positive with no sticky action. Took the opportunity to check the vacuum Solenoid next to it as well and all good.

Oskar

Smoke test your intake system . Unit is easy to make (via Internet ) will test hoses intercooler and manifolds for leaks in seconds .

What power source did you use to test the solenoid? It is powered by a 12V pwm with the duty cycle quite low for low CSOV valve openings so applying 12V direct to the solenoid won't give a proper indication of its operation. I don't know if the adjacent solenoid can be substituted to prove the solenoid in question.

Originally Posted by Graeme

What power source did you use to test the solenoid? It is powered by a 12V pwm with the duty cycle quite low for low CSOV valve openings so applying 12V direct to the solenoid won't give a proper indication of its operation. I don't know if the adjacent solenoid can be substituted to prove the solenoid in question.

It can also kill them.

Thanks again Graeme, didn’t consider the PWM but makes sense for varying the flow rate, does the solenoid on the bypass valve also operated on PWM? I did use direct 12 v, don’t think I can use the solenoid next to it as they have different sized ports. Will ask my mate how far he’s prepared to let me take his car apart. Alternatively I can test the solenoid at work as we have the equipment and knowledge to test it. Assume I should be able to feel the solenoid unrestrict the flow as I dial up the duty cycle just by sucking on it 😁😁

I would expect that you could tell if on low duty cycle that air can pass, really looking to confirm that it gradually opens more as the duty cycle is increased. A sudden opening then staying opened, albeit less, as the duty cycle is decreased may indicate that its valve is faulty. I'm aware that the solenoids can fail to work properly but I don't know if they fail totally or just become sticky.