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Hearing diverter valve sound after major service

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Hi all,


I did a large amount of work to my 08 Cayenne Turbo and am now hearing diverter valve/pressure relief sound if suddenly letting off the gas, especially at lower speeds.  It reminds me of what I have heard on other cars, but I’ve never had it on this car.  It’s not a “honk” per se; it’s what I consider normal DV sounds.


What I replaced;

- Coolant pipe, thermostat, water pump, acc belt

- Air filters (Mann)

- Spark plugs


I inspected the DV lines and did not see any issues, but maybe the hard line got damaged?  I realize I did a lot of work on it and may have caused this problem.  Or I might have fixed something as I replaced some aging vac lines that came apart during disassembly. I was also going to check the airboxes as maybe one/both is not closed correctly.


I am hoping this is normal or related to the non-OEM air filters.


Please let me know your thoughts!

Edited by millerchris85
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3 hours ago, millerchris85 said:

The car is now triggering P1666.  It seems to agree with me that something is not right.


Fingers crossed that I can find/fix the problem without much difficulty!


P1666 Overrun Recirculating Air Valve - Signal Implausible


Possible cause of fault
- Overrun recirculating air valve stuck in closed position at times (due to ice)
- Overrun recirculating air valve faulty

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19 minutes ago, Loren said:


P1666 Overrun Recirculating Air Valve - Signal Implausible


Possible cause of fault
- Overrun recirculating air valve stuck in closed position at times (due to ice)
- Overrun recirculating air valve faulty

To clarify - that’s the diverter valves, right? That’s where my research was pointing, but the “implausible signal” part is confusing.

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The diagnosis detects pulsations in the intake air tract from the boost pressure sensor reading. When the overrun recirculating air valve is stuck in closed position, these are produced by the exhaust turbocharger (pumping in the direction of the closed throttle valve).

This fault can also occur in extremely cold conditions when the membranes of the overrun recirculating air valves can be frozen solid for a short time just after you start the engine.


Boost Pressure Control.jpg

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The check valve right after the intake manifold is not allowing vacuum to go to the diverter valves.  When I disconnected it, the line to the diverter valves appeared to be pressurized.


Bypassed it and getting good vacuum to the diverter valves, and no longer having the sounds that I initially posted about, but P1666 is still triggering after high-boost situations.  I am curious if this is partially due to the lack of check valve, with the long-ish diverter valve lines seeing both pressure and vacuum now - taking longer to close the diverter valves (?).


New diverter valves and check valve ordered.  I also want to replace the plastic line under the intake manifold but struggling to find it so far.

Edited by millerchris85
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