Another Low Boost Thread

[vinnie mack]

Hey guys.. driving around the other day I noticed.. 4.5 to 5 (peak) psi sounds a bit low to me. Shouldn't I be around 6 - 6.5psi?.

If so, what are the usual problem spots for loosing boost.. vacuum lines?.

No rough idle, or performance loss (other then what i see on the gauge).. it may have been like that since i bought the car.

Any help is great.

(humpleg)

 

[Stormtrooper77]

I have been at 4.5 - 5 since the beginning.

 

[vinnie mack]

i thought that was kinda weak.. but i guess if yours is the same

 

[lisevolution]

These cars vary anywhere from 4-7psi... I've been between 5-6 since I got the car

 

[vinnie mack]

well 5-6 would be a little better but i dunno

 

[Drumfreak]

Does your boost gauge sit at zero while the car is shut off. I ordered a stewart warner vac/boost gauge and it sat at -3 vac while the car was off. Then it would peak at 3 to 4 psi at full boost with no boost controller. Is the boost the same for every gear, 2nd, 3rd, and 4th?

 

[Lodivigo]

Does your boost gauge sit at zero while the car is shut off. I ordered a stewart warner vac/boost gauge and it sat at -3 vac while the car was off. Then it would peak at 3 to 4 psi at full boost with no boost controller. Is the boost the same for every gear, 2nd, 3rd, and 4th?

Hmmm, you might have a kinked hose somewhere, my Stewart Warner leaks off to zero when I shut the car off. I installed one in a buddies car and it did the same thing plus other weird stuff. We popped the A-pillar back off and sure enough there was a kink in the hose.

And yeah, the boost varies greatly in these cars, mine was 6psi stock.

 

[Drumfreak]

Hmmm, you might have a kinked hose somewhere, my Stewart Warner leaks off to zero when I shut the car off. I installed one in a buddies car and it did the same thing plus other weird stuff. We popped the A-pillar back off and sure enough there was a kink in the hose.

And yeah, the boost varies greatly in these cars, mine was 6psi stock.

Actually I called the company who sold it and got a new one for free cuz the gauge was damaged in shipping. It was a while ago. I was just offering a possible solution to the gauge reading low and the gauge zero'ing out properly is a good troubleshoot. I have had wierd issues with other boost gauges though like spiking to 15 psi when at stock boost. Turns out it was a bad, flexible vacuum hose stretching and messing up the reading. Boost varies for too many reasons: outsid temp, mods, going up a hill or going down a hill, different gears, what rev you floor it at. Even with my EBC I cant seem to ever have a steady 9 psi on a consistent basis.

 

[vinnie mack]

yeah it is a Stewart Warner and it doesn't return exactly to 0 when i shut the car off.. isn't it supposed to? (return to 0 that is). This may be a problem.. i knew there were problems with these gauges but.. i didn't think it would mess with the reading that much. Also another thing I noticed it starts to go nuts at peak boost, bouncing like crazy, is it supposed to do that? lol.

Yes most if not every gear and every time i get no more then 5psi.

 

[Drumfreak]

yeah it is a Stewart Warner and it doesn't return exactly to 0 when i shut the car off.. isn't it supposed to? (return to 0 that is). This may be a problem.. i knew there were problems with these gauges but.. i didn't think it would mess with the reading that much. Also another thing I noticed it starts to go nuts at peak boost, bouncing like crazy, is it supposed to do that? lol.

Yes most if not every gear and every time i get no more then 5psi.

Yes it should. Mine will stop right before zero ( like .25 in the vac) when the car is off but that is considered a reasonable gauge tolerance. Where does yours rest when the car is off? So if it sits at -2 in the vac you are probably peaking at 7 psi. I would demand a new one from the supplier you got it from unless of course you bought it used. Question: are you using the supplied boost line that came with it? If yes then that is good since that is what I did and i've had no problems. I would still have faith in Stewart Warner. As far as your boost bouncing around I'm not sure. What do you mean by bouncing around?

 

[fr0st]

Hey guys.. driving around the other day I noticed.. 4.5 to 5 (peak) psi sounds a bit low to me. Shouldn't I be around 6 - 6.5psi?.

If so, what are the usual problem spots for loosing boost.. vacuum lines?.

No rough idle, or performance loss (other then what i see on the gauge).. it may have been like that since i bought the car.

Any help is great.

(humpleg)

mine goes to 6.25 on a good day.. and sometiems it will go to 5.9.. depends on alot of things.. first off, outside temp plays a role.. i would hit 7 psi at -10 degrees..

oh and the max boost will only be reached in 4th or 5 th gear.. well mine it like that .. in third or second gear, i wont make it to 6 ..

so check your max boost in 4th or 5 gear..

 

[vinnie mack]

Yes it should. Mine will stop right before zero ( like .25 in the vac) when the car is off but that is considered a reasonable gauge tolerance. Where does yours rest when the car is off? So if it sits at -2 in the vac you are probably peaking at 7 psi. I would demand a new one from the supplier you got it from unless of course you bought it used. Question: are you using the supplied boost line that came with it? If yes then that is good since that is what I did and i've had no problems. I would still have faith in Stewart Warner. As far as your boost bouncing around I'm not sure. What do you mean by bouncing around?

Yeah I am using the hard-line with a retrofitted connector at the end into the soft (rubber) line, i will double check my resting point today. As for the bouncing say i'm in 2nd gear and mash the throttle, the gauge will go to around 5psi and bounce... if i were to compare it to something i'd say like hitting a rev limiter only the needle bounces faster. You know what I will take a video with my phone today.. show you what I mean.

 

[vinnie mack]

attached is the resting point of the car.. sorry for bad pics.. my cell phone.

Car is off.

 

[BradC]

mine goes to 6.25 on a good day.. and sometiems it will go to 5.9.. depends on alot of things.. first off, outside temp plays a role.. i would hit 7 psi at -10 degrees..

oh and the max boost will only be reached in 4th or 5 th gear.. well mine it like that .. in third or second gear, i wont make it to 6 ..

so check your max boost in 4th or 5 gear..

Please don't check your max boost in 5th gear.

Your car should build full boost with no issues in second.

 

[Stormtrooper77]

I would use 3rd or 4th gear. Your max boost should be reached in either of these, usually 4th. This is why when you dyno these are the gears they mostly use.

 

[BOOSTR]

Based on the gauge position with the car off, your probably right in the mix given the wide variance of MSP stock boost. I've always used 3rd gear to check and set my boost.

 

[RedBli$$]

so when the cars at idle, it should read like -20 to -25 vac. right?

 

[BOOSTR]

Ideally 20-22 IMO at idle. 17-22 is considered the sign of a healthy engine however. My MSP has always been 20. But no two gauges are alike, especially the ones drop kicked in shipping and neither are MSP's.

 

[vinnie mack]

lol drop kicked during shipping. I took a video of the crazy bounce it does.. although I have no way to upload right now from my phone but will post when I can.

I also noticed I hit 6psi today so i think everything is alright.. just so irritating when the gauge starts going nuts you can't tell where you are on the gauge.

 

[Drumfreak]

I would use 3rd or 4th gear. Your max boost should be reached in either of these, usually 4th. This is why when you dyno these are the gears they mostly use.

That isn't why they dyno in those gears. They dyno in those gears because they are closest to 1:1 ratio. I guess you are partially correct because you would want to dyno at more boost.