Your gauge is showing vacuum, not boost.

dwb said:

Your gauge is showing vacuum, not boost.

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Sorry I've never had a turbo car trying to learn about it so vac has nothing to do with boost. Other side says pressure.

If you're trying to boost it sitting still it doesn't work that way generally.

First thing I check if you can only reach 0-1psi of positive pressure is check if the wastegate arm is still attached to the flapper. mine sometimes slipped off due to a janky Cotter pin arrangement

Iceman8079 said:

Sorry I've never had a turbo car trying to learn about it so vac has nothing to do with boost. Other side says pressure.

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Vacuum is the opposite of boost. Vacuum is created from the pistons sucking air into an engine. Boost is created by the turbo pushing air into the engine.

An N/A car can, at best, reach 0 on that gauge at WOT (maybe slightly higher from ram air or charge pipe resonance. Zero is the same as atmospheric pressure. A healthy engine at sea level might make 18-20 inches of mercury (inhg) vacuum at idle. A supercharged or turbocharged engine can create positive pressure (boost) by forcing air into it. At 1 bar (14.5 psi) boost twice as much air is entering the cylinder as at zero.

As mentioned, you usually won't make any boost without a load on the engine.

Sorry to keep asking so many questions. 98 gst runs great no dash lights on. Says I have vacuum pressure on gauge. Turbo says it's building but not kicking in. Not for sure the problem any help would be appreciated.

My man, describe the problem in more detail. Yes, a loose BOV can cause you to lose boost.

pauleyman said:

If you're trying to boost it sitting still it doesn't work that way generally.

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I've drove car got it up to 50 mph. I've even held

Vegas Smith said:

My man, describe the problem in more detail. Yes, a loose BOV can cause you to lose boost.

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Ok, Guage is showing vacuum pressure and my boost Guage shows boost. I can't hear my turbo kicking in car shifts fine had it up to 110 mph. Everyone has told me that turbo should be making a whistle sound. Turbo builds on Guage. Can't hear my blow off valve as well. No leaks anywhere that I can find.

You are still being very unclear. Reread what you wrote.
What is the problem? Does the boost gauge (not the stock one) read boost when accelerating? If so how much? Does the car not drive well? Have you inspected or tested anything?

pauleyman said:

You are still being very unclear. Reread what you wrote.
What is the problem? Does the boost gauge (not the stock one) read boost when accelerating? If so how much? Does the car not drive well? Have you inspected or tested anything?

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Sorry stock boost Guage car runs good was told that I should be able to hear turbo when running should make a whistle sound.

Your car is an automatic and its running a 1g dsm blow off valve so your wont really hear it

The only time you should hear it is when you accelerate and then completely let off the throttle you might hear a whooshing noise

Don't worry about what you think you should hear. Most cars with turbo aren't going to sound like the movies. If it runs good and you can "feel" the boost while driving, I wouldn't think twice about what you can't hear. If you're hearing strange noises on the other hand, it would be worth investigating.

Most likely what you are talking about is the Blow Off Valve (BOV), which should only open when you have boost built and then suddenly close the throttle plate. Looking at your pictures, it appears you have a 1g BOV routed back to the intake snorkel. That's the proper configuration when running a stock 2g MAF like you are. It won't make any movie-like sounds, maybe a small psssht.

Looks like it's been sitting for a while. If I were you, I would start with some general maintenance. So timing belt, serpentine/PS/AC belts, fluids, maybe coolant hoses, new dipstick, clean up the battery contacts, boost leak test, spark plugs/wires, etc. Cover up your air filter and any sensitive electronics and blast it with a pressure washer.

Where is your boost gauge attached to? Does it ever go up to 0 or part it?
The factory gauge isn't actually connected to anything, it's the ECU estimating whit it thinks the boost should be based on airflow, temp, throttle position.

dwb said:

Don't worry about what you think you should hear. Most cars with turbo aren't going to sound like the movies. If it runs good and you can "feel" the boost while driving, I wouldn't think twice about what you can't hear. If you're hearing strange noises on the other hand, it would be worth investigating.

Looks like it's been sitting for a while. If I were you, I would start with some general maintenance. So timing belt, serpentine/PS/AC belts, fluids, maybe coolant hoses, new dipstick, clean up the battery contacts, boost leak test, spark plugs/wires, etc. Cover up your air filter and any sensitive electronics and blast it with a pressure washer.

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I was just going by what guy I bought it from told us. He also said that it had it 2 stepping it as well. I have cleaned up engine bay and everything was old alternator is bad and will affect alot of my issue as well. Thank u for advice.

Thank u very much i will take care of that.

steve said:

Where is your boost gauge attached to? Does it ever go up to 0 or part it?
The factory gauge isn't actually connected to anything, it's the ECU estimating whit it thinks the boost should be based on airflow, temp, throttle position.

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Just going bye the factory gauge in dash. Was told that bov is set up to make noise every shift. I can't feel boost kicking it but it gets up to speed quick. Was told it is pushing 15/20 lb boost.

What on earth were you pushing it to 110 for if you are even slightly considering it has an issue? The factory gauge is essentially your ECU guestimating how much boost you have based on engine load. It cannot be trusted as you could have a blown coupler (essentially a full boost leak) and it will still read that you are building boost. The car would run like poop, but it would still read boost.

DiSeM said:

What on earth were you pushing it to 110 for if you are even slightly considering it has an issue? The factory gauge is essentially your ECU guestimating how much boost you have based on engine load. It cannot be trusted as you could have a blown coupler (essentially a full boost leak) and it will still read that you are building boost. The car would run like poop, but it would still read boost.

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I was making sure after all the fluids were changed and new plugs wires and fuel it would get up and go.

Iceman8079 said:

I was making sure after all the fluids were changed and new plugs wires and fuel it would get up and go.

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Gotcha. Well it sounds like you just aren't hearing what you expect to hear but the cars running the way that it should. I daily drive a stock ecu with a 14b which requires MAF and recirculating BOV so its very quiet on shift naturally. You can hear the slightest noise between shifts, but nothing like the other running with speed density and a vent to atmosphere BOV. Night and day. If you want to change the sound, you need to invest in a means of handling it. I think at the very least a MAFT, which still requires ECM Link so by that point you may as well just switch to speed density. It doesn't look like you have an upgraded ECU yet, you will need to start there if you want these upgrades.

DiSeM said:

Gotcha. Well it sounds like you just aren't hearing what you expect to hear but the cars running the way that it should. I daily drive a stock ecu with a 14b which requires MAF and recirculating BOV so its very quiet on shift naturally. You can hear the slightest noise between shifts, but nothing like the other running with speed density and a vent to atmosphere BOV. Night and day. If you want to change the sound, you need to invest in a means of handling it. I think at the very least a MAFT, which still requires ECM Link so by that point you may as well just switch to speed density. It doesn't look like you have an upgraded ECU yet, you will need to start there if you want these upgrades.

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Sounds great thank u very much. This page has been very helpful

@Iceman8079 - a lot of abbreviations and alphabet soup on here. Sounds like you are inexperienced with not only turbos and forced induction, but also with DSMs and performance cars/engines in general. If so, that is perfectly okay. Don't let the alphabet soup and technical information (or us) intimidate you. Feel free to ask your questions, no matter how small they may seem to you. You might get told to research instead of getting the direct answer, but that would be for your benefit. These cars are considered treasures by most of the experienced folks on here and helping others learn and keep these cars on the road, from being abused, and out of the crusher is a primary goal.

I don't mean to belittle or talk down to you; if that's how I am coming across I apologize. I just want you to feel like you can ask anything and get the help you want without reservation or judgment. Nobody on here was born with a wrench in their hand; we all had to learn, and many of us are still learning.

CKOPOCT said:

Nobody on here was born with a wrench in their hand; we all had to learn, and many of us are still learning.

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I'm sure my mother is grateful for that.

I wish there was an internet back when I was first learning how things worked, it would have saved a few beatings when you asked too many stupid questions without thinking things through. That did tend to accelerate the ability for critical thinking (and how quickly you could run) but it wasn't very fun. You learned to read everything you could get your hands on and ask good questions so you didn't get shooed out of the garage. By the time I got my DSM the first thing I did was walk back to the service desk and order the factory manuals and read them.

Now you can download most of them and print out what you need to a given task.

CKOPOCT said:

@Iceman8079 - a lot of abbreviations and alphabet soup on here. Sounds like you are inexperienced with not only turbos and forced induction, but also with DSMs and performance cars/engines in general. If so, that is perfectly okay. Don't let the alphabet soup and technical information (or us) intimidate you. Feel free to ask your questions, no matter how small they may seem to you. You might get told to research instead of getting the direct answer, but that would be for your benefit. These cars are considered treasures by most of the experienced folks on here and helping others learn and keep these cars on the road, from being abused, and out of the crusher is a primary goal.

I don't mean to belittle or talk down to you; if that's how I am coming across I apologize. I just want you to feel like you can ask anything and get the help you want without reservation or judgment. Nobody on here was born with a wrench in their hand; we all had to learn, and many of us are still learning.

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I definitely thank all of for the advice and help.