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Boost Solenoid Valve

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A few days ago I noticed the vacuum pipe which goes from the plenum to the boost solenoid valve was hanging off (which explains why I wasn't getting overboost codes when both wastegates were seized). Question for you guys, there were x2 nipple connectors on the bottom of the solenoid valve and the left one had a small section of pipe which I assumed was the correct one to connect to as the pipe hanging down had a plastic tee-piece on it. So, what's the right side nipple one for, can anyone check and see if they have something attached to it?

I tried to connect up a boost gauge today and tee-pieced into the pipe which goes from both dump valves and then tee-pieces itself into the pipe below the boost solenoid valve. However, I am not getting any reading on the gauge, just sits at "0". I know the gauge works cause if you suck/blow on the pipe connected the needle moves up/down.

I am now thinking the solenoid valve it maybe gone?

Any help/advice etc is appreciated.



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Hi Buckie,

I would expect the MAP sensor to still provide the manifold pressure for the ECU even if the solenoid valve was not connected to the manifold. So if you were over boosting for longer periods the ECU should have raised the respective error codes. I'd also expect that due to the manifold venting directly to air, that you essentially have a small boost leak, which would reduce the maximum boost you were developing.

I also have a theory that if your wategates are not connected to the manifold and are never pressurised and hence never move, that the wastegate will seize up over time. I have the forge wastegates with stronger springs and I have had some problems with my wastegates seizing. I think this might be because the stronger spring stops the wastegate moving during normal driving. It's only on high boost that the spring is overwhelmed, and I sadly don't get to use full throttle on every drive (wet roads. traffic and speed limits). I'd be interested to hear other peoples views on this.



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Thanks for the reply Peter!

I know the previous owner replaced both actuators for the upgraded billet alloy ones. The garage told me both wastegates were seized solid, tried everything to free them up with no lock. The chap said it looks like they have been like this for a while which may explain if the pipe connecting to the solenoid was off and hence no pressure sent to the actuators to then operate each wastegate - this sound correct?

Concenring the boost gauge and solenoid valve, do you think the valve has gone as there's no boost reading on the gauge?? Also, I have connected to the left side nipple thing, am assuming thi is correct (fairly confident as there was already a small section of vacuum pipe connected to it and the pipe (with tee-piece, one which goes into the plenum) was hanging below.

Thanks, am looking forward to getting the car all sorted again, x2 fresh turbos, actuators, braided leads and boost gauge (which fits snug in the coin tray next to my racelogic LCD display).



Sorted it - boost gauge and dump valves connect to the black vacuum pipe which fits onto the front of the plenum.

Appears that the person who tried to fit the dump valves before was connecting (tee-piece) into the wrong pipe (ie the one which comes out the bottom of the solenoid valve....

Now both the dump valves and boost gauge connected onto that single pipe, works a treat.


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