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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-19-2012, 06:03 PM   #1
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Default Boost is gone

I barely get any positive boost at heavy throttle or WOT. (according to the Boost gauge)

So I cleaned up the Actuator arm and tested it, opens and closes 100%.

To check the Boost Control solenoid, I disconnected and plugged the lines to Boost control unit. Started it and the Actuator arm stayed down for full boost. Took it for a quick ride, didn't pound it, but the car is pulling just the same, can't get any positive boost.

I'm not sure what I know right here. Can somebody explain what'* happening.

Thanks guys.
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Old 05-19-2012, 06:12 PM   #2
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I thought the arm stayed up while at idle and it goes down when you romp on it?
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Old 05-19-2012, 06:25 PM   #3
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Originally Posted by Mike1995 View Post
I thought the arm stayed up while at idle and it goes down when you romp on it?
Hey Mike,..

Right. The "test" for the Boost Control Solenoid is to cut off any flow in or out of the Boost Control/Actuator unit. Supposedly, that way you have full boost (the arm is down) when you drive it,. Which should be a Max boost condition. But it ran like it had been.

I checked the test here in TechInfo and the description of how to do the test made no sense.

You remove the hose between the BCA and BCS, then you plug it. Great, your standing there with a plugged vacuum tube in your hand.

What I'm trying to find out, does this mean the BCS is bad. And if I'm lucky just what the BCS does.

Thanks
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Old 05-20-2012, 05:58 AM   #4
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I believe the BCS works off of engine vacuum/pressure. At idle, there is about -10psi vacuum. When you accerlate the pressure changes and the boost from the supercharger pushes against the BCS thusly closing it. I'm sure Boosty will come in and educate us correctly.
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Old 05-22-2012, 04:12 AM   #5
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Originally Posted by Mike1995 View Post
I believe the BCS works off of engine vacuum/pressure. At idle, there is about -10psi vacuum. When you accerlate the pressure changes and the boost from the supercharger pushes against the BCS thusly closing it. I'm sure Boosty will come in and educate us correctly.
Yes, thanks. I think I now get how the solenoid senses and controls/offloads intake through the */C. Basically, if you do the BCS test and ya aren't in a full boost state, you're running N/A and the BCS is sending no news otherwise, to the PCM.

Tonight I just pulled it and checked with a multimeter for resistance and got zip, zero, nada. i don't remember picking it up, but I found one in my parts cabinets. the car'* back to full throat again.

I sheared an endlink a month ago, and somehow nuked the idler pulley inside the engine mount, on the */C belt circuit. I got distracted thinking I might have a bent the */C pulley or snout. this showing up at the same time, was just a coincidence.

All seriousness aside...

Boosty? the word going round Phila in the Bonnevillism circles, is that he went too fast one day and scared himself. So he retired. He spends most of his days now sitting in his driveway in an old man'* car with the engine off, sipping tea and making loud "Vrooom Vrooom" noises to try to recapture the good ol' days.

Last club meeting, we had a minute of silence for the passing of the Legend in the History of Bonnevilles. I have to admit there was a tear or two. Hey, some of the best live fast, and retire early.

Somebody suggested we take up a collection and buy him a walker with an M90 V5 mounted on it. One of the young kids suggested we buy some testosterone that they advertise on TV. We were thinking maybe it would help him grow back some nads, and he'd get back into the Bonneville faith.

If anybody asks for me, I'll be in a really deep duck and cover for a while.
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Old 05-22-2012, 05:48 AM   #6
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Oh, no. The MAP sensor senses the pressure. If it sees too much the PCM tells the solenoid to open/close so the BCS will open back up thusly "blowin off boost".
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Old 05-22-2012, 08:58 AM   #7
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All seriousness aside...

Boosty? the word going round Phila in the Bonnevillism circles, is that he went too fast one day and scared himself. So he retired. He spends most of his days now sitting in his driveway in an old man'* car with the engine off, sipping tea and making loud "Vrooom Vrooom" noises to try to recapture the good ol' days.

Last club meeting, we had a minute of silence for the passing of the Legend in the History of Bonnevilles. I have to admit there was a tear or two. Hey, some of the best live fast, and retire early.

I only make vroom vroom noises in my sleep according to my financee.

Somebody suggested we take up a collection and buy him a walker with an M90 V5 mounted on it. One of the young kids suggested we buy some testosterone that they advertise on TV. We were thinking maybe it would help him grow back some nads, and he'd get back into the Bonneville faith.

If anybody asks for me, I'll be in a really deep duck and cover for a while.
Charlie..how are ya, old man?

Currently there'* two cammed, IC'd, Gen V'd drivetrains (trans too) sitting in my garage awaiting me. Next to them is a cammed Gen 3 motor. Add my car to the garage and there'* a rockered, Gen v'd w body. I try to keep a low profile since I'm driving a white car, we all know they are cursed.
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