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09-30-2015, 10:55 PM | #1 |
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boost solenoid testing
Hi guys - just a quick question regarding our boost solenoid - it is supposed to hold vacuum on the inlet side (where the hose from the solenoid runs to the canisters). Just wondering what would be an acceptable bleed off time for the vacuum? 1 of mine is at 26 in mercury, the other is at 25. This is with the car on idling and vacuum gauge attached. When I turn the car off vacuum is still there but if you stand there and watch it, it starts to lose vacuum very slowly. Does that mean they have gone bad?
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09-30-2015, 11:03 PM | #2 |
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Are you running a tee off the inlet (its labelled as vac)?. I have brand new genuine BMW solenoids and they slowly bleed off vacuum when sucked on with a syringe (maybe a few mls over 15-20 seconds).
The solenoid mechanism only opens the valve, it relies on vacuum to such it back shut and can sometimes leak slightly under test. If its slow then don't worry about it, the valves are not perfect seals. This doesn't mean they're not faulty though, I think they may still stuff up at higher temps. I have had an overboost at the racetrack and I think it was the solenoids leaking vacuum (closing the wastegates). Sounds similar to your issue in your other thread. I haven't reproduced the issue and will just install my set of solenoids as preventative maintenance.
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10-01-2015, 01:14 AM | #3 |
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When you test the solenoids did you disconnect the pipe that joins them together, as they share vacuum.
What you have to do is disconnect the vacuum balancing pipe and test the vacuum on each solenoid separately but make sure you have the other solenoid blocked off so it doesn't suck air while testing the other solenoid. |
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10-01-2015, 05:45 AM | #4 | |
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10-01-2015, 05:50 AM | #5 | |
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10-01-2015, 06:03 AM | #6 | |
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I have bench tested these things with a power supply and found that a brand new one can be made to leak after solenoid activation (just put 12V across the terminals) if you don't have a strong enough vacuum source to snap the valve back shut. I have heard about sticking wastegates due to heat but I haven't seen evidence to support that either. My car drives fine otherwise and I am not 100% sure if mine was even a wastegate control issue since I actually had the wrong firmware loaded on my Procede when I was at Winton raceway.
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10-01-2015, 03:15 PM | #7 | |
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You have to disconnect the balancing pipe completely and test at that outlet with the car running, mine where 16 and 18, with the balancing pipe in place I was reading 20 to 21. After new solenoids where installed I got 26 across from both from memory. So take the reading at the point where the balance pipe is not at the canister |
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10-01-2015, 06:52 PM | #8 | |
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