Boost Actuator / Valve
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Joined: Jun 2002
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From: Bedroom, Ontario

Yes Doc J.. it spiked and reacts to quick burps of gas ( 1.XX Volts.. it was quick ).. didn't try to gradually increase throttle since it'* in park and free revving so didn't want to rev hi for long without load and sure as hell not going to stick my head, body in there and let someone power brake
Checked the movement of the BCA and it seems to move freely when off with a spring feel of restraint.. and power brake and see it moving up into the BCA when the more gas is applied..
Around town.. It has no problem it seems below zero.. but for example if I need to pass and I romp on it some but not to WOT.. the gauge will fly up to boost.. but it will drop down in 2 steps.. roughly bout 1.5 seconds apart.. and you can see the needle wiggle as if tryin to climb back up but won't.. and it would drop it back down to slightly above zero... and I can that initial oomph feel but as the boost drops.. I can feel it
But there will be times it will drop down to the first mark of boost before zero.. and @ times it'* higher.. I was wondering if maybe the vacuum line to the MAP maybe clogged somehow.. will have to get my hands on some compressed air and see.. doubt thats it.. but worth a shot.
Read for codes again.. and still none stored.
Checked the movement of the BCA and it seems to move freely when off with a spring feel of restraint.. and power brake and see it moving up into the BCA when the more gas is applied..
Around town.. It has no problem it seems below zero.. but for example if I need to pass and I romp on it some but not to WOT.. the gauge will fly up to boost.. but it will drop down in 2 steps.. roughly bout 1.5 seconds apart.. and you can see the needle wiggle as if tryin to climb back up but won't.. and it would drop it back down to slightly above zero... and I can that initial oomph feel but as the boost drops.. I can feel it
But there will be times it will drop down to the first mark of boost before zero.. and @ times it'* higher.. I was wondering if maybe the vacuum line to the MAP maybe clogged somehow.. will have to get my hands on some compressed air and see.. doubt thats it.. but worth a shot.
Read for codes again.. and still none stored.
Thread Starter
Senior Member
True Car Nut
Joined: Jun 2002
Posts: 3,266
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From: Bedroom, Ontario

OK BCA movement and the lil "L" move fine and checked vacuum line, they hold vacuum ( ala vacuum gauge ). Wondering if it could be the spring the Actuator (Bruce recommendation ). So wonderin if anyone with series II L67 with access to a vacuum gauge can do me a favor and find out how much vacuum pressure is required before the actuator fully opens and dump the boost on the actuator.
thanx
thanx
Well, since we are on the subject. I have noticed a dust line on my BCS. The line was about an inch from the bottom though. How could I disconnect this BCS, or atleast let me have full boost?
Originally Posted by Drifter420
OK BCA movement and the lil "L" move fine and checked vacuum line, they hold vacuum ( ala vacuum gauge ). Wondering if it could be the spring the Actuator (Bruce recommendation ). So wonderin if anyone with series II L67 with access to a vacuum gauge can do me a favor and find out how much vacuum pressure is required before the actuator fully opens and dump the boost on the actuator.
thanx
thanx
Thread Starter
Senior Member
True Car Nut
Joined: Jun 2002
Posts: 3,266
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From: Bedroom, Ontario

Well.. thinkin it was BCA springs that maybe weak.. checked the MAP sensor.. and they both read low.. Bruce was nice enough to read his MAP sensors on his 97 also for me, and mine was way off
He got 4.8V and 2V @ idle. While I have 0.8V@ idle and 1.8V. ON Both..
So I think the PCM is on it'* last leg... if that'* the case.. INTENSE PCM??
But was also thinking.. how would the MAP or PCM dump boost? I was under the assumption that they control via BCS so if that thing is bypassed, there shouldn't be able to dump boost unless there'* a built in bypass somehwere else? ( Like for shifting between gears and such? ). I'm not Boost headed in knowledge.. so wat you think? Everything so far points to PCM. But can't see how it dumps boost...
Saveing up the coinage for the PCM
So I think the PCM is on it'* last leg... if that'* the case.. INTENSE PCM??
But was also thinking.. how would the MAP or PCM dump boost? I was under the assumption that they control via BCS so if that thing is bypassed, there shouldn't be able to dump boost unless there'* a built in bypass somehwere else? ( Like for shifting between gears and such? ). I'm not Boost headed in knowledge.. so wat you think? Everything so far points to PCM. But can't see how it dumps boost...
Saveing up the coinage for the PCM
Originally Posted by Drifter420
Well.. thinkin it was BCA springs that maybe weak.. checked the MAP sensor.. and they both read low.. Bruce was nice enough to read his MAP sensors on his 97 also for me, and mine was way off
He got 4.8V and 2V @ idle. While I have 0.8V@ idle and 1.8V. ON Both..
So I think the PCM is on it'* last leg... if that'* the case.. INTENSE PCM??
But was also thinking.. how would the MAP or PCM dump boost? I was under the assumption that they control via BCS so if that thing is bypassed, there shouldn't be able to dump boost unless there'* a built in bypass somehwere else? ( Like for shifting between gears and such? ). I'm not Boost headed in knowledge.. so wat you think? Everything so far points to PCM. But can't see how it dumps boost...
Saveing up the coinage for the PCM
So I think the PCM is on it'* last leg... if that'* the case.. INTENSE PCM??
But was also thinking.. how would the MAP or PCM dump boost? I was under the assumption that they control via BCS so if that thing is bypassed, there shouldn't be able to dump boost unless there'* a built in bypass somehwere else? ( Like for shifting between gears and such? ). I'm not Boost headed in knowledge.. so wat you think? Everything so far points to PCM. But can't see how it dumps boost...
Saveing up the coinage for the PCM
You're right, I didn't remember you had the bcs bypass done. Unless I'm not thinking clearly it should have effectively taken the PCM out of the picture. There isn't a lot of options to look at to diagnose this...Vacuum leaks, BCS, BCA, BCV, MAP, and other load sensors depending on the PCM'* control. Without the PCM having control that should be down to vacuum leaks, BCA and BCV..am I missing something? Since at some point it does go full boost, and on the other end does have -10 I would think we could eliminate the BCV and BCA as they're obviously capable of full movement. That leaves vacuum leaks. I guess it is still possible that the BCA has a leak in it, allowing inital full boost but slowly leaking back down...but didn't you say it works fine at WOT?
I'm starting to wonder if this is totally unrelated to the supercharger and associated actuators. Maybe at that throttle the engine isn't keeping steady vacuum...Coffee will help this
This COULD be caused by a leak at the SC outlet gasket. This sucker was immersed in water for awhile, then sat for a long period of time. Is your lower intake manifold oxidized in any way?
Would it be a good idea to pull the SC and simply clean the mating surfaces, install a new outlet gasket (cheap) and see where you sit? It might be worth it. That'* a fiber gasket. We've seen a car recently that had a leak from simply missing a torque sequence.
The environmental impact of the swim and storage may be causing this.
Would it be a good idea to pull the SC and simply clean the mating surfaces, install a new outlet gasket (cheap) and see where you sit? It might be worth it. That'* a fiber gasket. We've seen a car recently that had a leak from simply missing a torque sequence.
The environmental impact of the swim and storage may be causing this.
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