my boost readings [Archive]

03MSPRO

11-17-2003, 09:01 PM

My car boost varies from 5.0 to 6.5 psi. I guess that's normal, but why does it vary depending on what gear you're in? Like in 1st it boosts ~6, in 2nd it's ~5, and the highest boost is actually in 5th gear when it peaks to about ~6.5 psi.
Vacuum at idle is 20

1338

11-17-2003, 09:07 PM

sounds right that is what mine reads stock. but my Vac is at 25-28 at idle

[syko.xero]

11-17-2003, 10:56 PM

my car always boosts 7 @ 3500-5000 and then drops to about 5

CustomMSP

11-17-2003, 11:04 PM

Damn bro, how did you end up with a vac of 25-28?? Must be a very good seals inside the engine you got there.

acidbbg

11-17-2003, 11:07 PM

I don't think b/c the vaccum reads closer to 25..that means you have some good seals..

My turbo p5..at idle when i first start her up reads close to 20...than after 30-1hr worth of hard drving..it reads closer to 25-27!

Chas

CustomMSP

11-17-2003, 11:32 PM

I thought I read that somewhere, but if you thing about it that would make sense though

03MSPRO

11-21-2003, 08:31 PM

I've been driving a lot lately and looking at my boost gauge. During the day it peaks at ~6.5 psi and the drop and stays at ~5 psi. Is that normal? So how much is the car boosting, 5 psi?

jersey_emt

11-21-2003, 09:51 PM

Mine peaks at 7, stays there for a long time, then finally drops down to 6psi in higher RPM's.

csman22

11-24-2003, 12:36 PM

Don't mean to jack..but lately my MSP Vac reading is around 20 and sometimes dips to 18, I'm boosting about 8 or 8.25. Should I worry about the Vac reading (does a lower Vac redading imply anything?) and should it be always above 20 and [possibly read in the 22+ range like some of the p5's?

Thanks in advance for any input.

1338

11-24-2003, 12:45 PM

a lower vac reading means you have a vac leak some ware exp if it is under 20

csman22

11-24-2003, 12:55 PM

As I thought. I've actualy got and ERG engine light a few times, and this may be the cause. (the light went away after resetting the ECU but this Vac reading has to be related)

thanks for the input I appreciate it.

03MSPRO

11-24-2003, 04:51 PM

Originally posted by csman22
Don't mean to jack..but lately my MSP Vac reading is around 20 and sometimes dips to 18, I'm boosting about 8 or 8.25. Should I worry about the Vac reading (does a lower Vac redading imply anything?) and should it be always above 20 and [possibly read in the 22+ range like some of the p5's?

Thanks in advance for any input.

I would not sweat it!! My vacuum reading is the same as yours.
Most of the time around 20 and 18 with the AC on.

505zoom

12-09-2003, 05:24 PM

I just got around to hooking the boost/vac gauge on my TT back up, and I was shocked when it read -.59hkpa at idle. This converts to about -8.5 psi!!!! Major vacuum leak??? Or am I just missing something here???

505zoom

12-09-2003, 05:59 PM

Can one of you guys that are running the Blitz DTT tell me what it reads at idle?

servoeyes

12-09-2003, 06:06 PM

I'm with you 505zoom...I have the DTT typeX and it reads about -.75 hkpa once I get moving. Cold start idle it's around -.59 same as you.

505zoom

12-09-2003, 06:41 PM

Cool that makes me feel better. The car is running great, nice and rich still. I'm not sure if the conversion is different for vacuum or something, but it seems I would have noticed if there was a major leak like that.

SirJaime

12-12-2003, 12:46 PM

WOW you people are talking a 20. reading @ idle and im getting a minus reading of -.71 @ idle and will not even get to a 0. till I hit around 3000 or 4000 rpms! HELP ME HELP Me

I just put this in last night !

servoeyes

12-12-2003, 01:48 PM

I figured out what it is...boost gauges with vaccum readings switch over to a different unit in vacuum. It's not psi any more, I think it's either inHG or mmHG. Someone took a pic of their boost gauge, and it listed the units there. That would explain the difference that we're all seeing.

loudpdl

12-12-2003, 02:07 PM

Originally posted by 03MSPRO
My car boost varies from 5.0 to 6.5 psi. I guess that's normal, but why does it vary depending on what gear you're in? Like in 1st it boosts ~6, in 2nd it's ~5, and the highest boost is actually in 5th gear when it peaks to about ~6.5 psi.
Vacuum at idle is 20

I think the boost varies depending on gear due to the load on the engine. In 1st, the revs increase so rapidly that there's not much opportunity for pressure to build...and so on.

marashka

12-12-2003, 02:13 PM

All the turbo cars i've owned(R32, MR2, Sylvia), including the MSP i was able to get the highest boost readings in 3rd gear and up.....first gear i think is powerfull enough not to use all the boost that turbo can put out. My vac reading is 19 when i just start the car and goes 20-23 after the car is warmed up.

Slickfabo

12-12-2003, 02:36 PM

Orignally posted by SirJaime
WOW you people are talking a 20. reading @ idle and im getting a minus reading of -.71 @ idle and will not even get to a 0. till I hit around 3000 or 4000 rpms! HELP ME HELP Me

I just put this in last night !

Mine also reads the same :confused:

SirJaime

12-12-2003, 02:38 PM

I'm still waiting on Blitz to write me back about the hkP reading !

Its NOT psi