Over boosting (stock 1993 SS)

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Gregmckenna
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Posts: 138
Joined: Mon Jan 22, 2007 1:28 am
Location: N.B.Canada

Over boosting (stock 1993 SS)

Post by Gregmckenna »

Hey fellas, little bit about me. I've been hiding on here a few years my first car as a kid (16) was a 1992 SS which I did a FMIC tdo4 etc be for it made it's way to the junk yard as scrap.

I'm from the east coast of Canada, after 8 years many cars later I stumbled upon a local unmolested fairly rust free 93 SS.

As I said it's bone stock and an older fella owned it so I doubt it has been tampered with.

The other night I noticed it will hit fuel cut in 4th, factory boost is 9lbs. Fuel cut is just north of 12.
So I got myself a boost gauge it's just a cheapo but hey it measures boost. Sure enough the cars over boosting

1st/2nd I'm hitting right around the 10 mark
3rd I'm hitting just over 10lbs
4th I am creeping up over 12 and hitting the cut.

No worries guys I don't need a lecture it's not intercooled I'm well aware of the limitations and that it isn't a good idea to be over boosting on a vf11 with no intercooler or fueling/exhaust.

I've done a little searching but can't stir anything up.

What do you guys think it is?

I want to lean toward the BCS but I'm also not super familiar with how they work or if this would cause my conditions.

It is creeping up if it were wastegate being stuck or the line being off I would assume I would see more creep then I am especially in 3rd. I have checked my lines over and all seems good.

Can I hook a MBC in line set to 9lbs to bypass the BCS but without causing a CEL or any other issues?
James614
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Re: Over boosting (stock 1993 SS)

Post by James614 »

I'd put money on the BCS getting tired (assuming the car is actually unmodified... but exhaust mods, especially downpipes, have been known to cause boost creep in higher gears). Yes, you can throw a MBC on there to bypass the BCS without causing a CEL. You can just cap off the BCS vacuum fittings and leave it plugged in to dodge the CEL.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
Gregmckenna
First Gear
Posts: 138
Joined: Mon Jan 22, 2007 1:28 am
Location: N.B.Canada

Re: Over boosting (stock 1993 SS)

Post by Gregmckenna »

Thanks for the reply, I'm going to pick up some vacuum line and try that in case I have a crack from old brittle lines that I can't see visually. Then if that doesn't work MBC it is
Legacy777
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Re: Over boosting (stock 1993 SS)

Post by Legacy777 »

Yeah, I'd start with verifying or replacing the vacuum lines associated with boost control. Start with that and see how things work.
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