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Old 08-03-2006, 01:38 PM   #1
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Default boost/bypass control actuator

I've been trying to find a cheap BCA for my " '95 SSEi" sueprcharger. The dealer wants $300+ for that dumb little canister, and GMpartsdirect wants half that. Still too much, to me.

I gave Magnuson a call and asked if I could purchase a BCA by itself. They said yes, for $40 . That'* reasonable. I recieved it from them yesterday and installed it. It looks very similar to my stock one, though made out of plastic instead of metal.

However, whenever the engine is running, the shaft is retracted, giving full boost at idle. Off of the */c, it feels like the rod moves fine, but is not as resistive to movement as my stock one, which I think is the problem. When I disconnect the top vacuum line, the rod extends, and gives no boost at idle (like it should) but retracts all the way again when plugged back in.

I gave a call back to Magnuson, and they said it must be defective, and are shipping me out another one (they're new, btw). Their service is excellent. But, am I missing something to this? I studied what I did, and there'* not much to it. I loosened the two 10 mm bolts that hold it to the */c and tried different angles (from what I've read, have an effect on how responsive the BCA is) but nothing seemed to help. It'* not like it'* binding; with the engine off, I can move the rod and the little arm like I could with the old one.

Thanks guys. Has this ever happened before?
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Old 08-03-2006, 03:44 PM   #2
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At idle, the shaft should be retracted, but that should be no boost... can you get a pic of your setup?
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Old 08-03-2006, 09:27 PM   #3
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Here you go. This is with my stock BCA installed. The vacuum line on the top normally has a zip-tie



This is with the engine off. When I rev it, the shaft retracts and gets sucked into the canister, pulling the little arm upward
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Old 08-03-2006, 11:32 PM   #4
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See that top vacuum line? If it leaks or is disconnected, it won't work. It looks way too big to me.
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Old 08-03-2006, 11:35 PM   #5
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Yes sir. I do understand, but it is not leaking. Maybe one notch too big, but the usual zip tie takes care of it. At any rate, if the new BCA is good, it would be flowing too much air.
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Old 08-03-2006, 11:42 PM   #6
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The position the wastegate rod is sitting right now would be boost. It'* the relaxed state when pressure on top and bottom of the BCA are the same. Does that little foot on the rod sit all the way down against that stop?
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Old 08-03-2006, 11:46 PM   #7
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Mr. Wilkoff:

Yes, the little arm is against the stop. I've always thought that this position would be bypass. As I said, when revved, it moves up. This just doesn't seem right to me
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Old 08-03-2006, 11:50 PM   #8
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What is the lower line on the BCA connected to that we can't see (on the throttle body side of the lower half of the BCA), and why do you have the BCS connected if you have no PCM control of it?
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Old 08-03-2006, 11:59 PM   #9
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The lower one is to the BCS. how can I get rid of it? It'* just kinda sitting there, though attached like it usually would be
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Old 08-04-2006, 12:00 AM   #10
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Willren: can you confirm that extended=bypass=idle and that retracted=boost=throttle ?
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