Hi guys i own a 1998 S70 T5 SE i just installed a autometer boost gauge....well i was testing it out yesterday and my car was only making 9 pounds of boost well thats what the boost gauge was reading...when i live the car at idle the needle is on 20 vaccum....should my car be making more boost guys and what could be the problem??....tks from Rob (custom 2 1/2 exhaust hks blowoff valve

I thought you were running both the factory bypass valve and blow off valve, right? Why would you want to do that? That sounds like the cause to your problem.

I have the almost set-up as your car. There are 2 possible problems.

1. Maybe the guy place the vaccum line to a wrong place, my friend's c70 have this problem before.( only show 10psi of boost with GIAC chip)

2. your SSQV have some problem.(my car running ~15psi with GIAC chip and SSQV)

You can sent a private E-mail to me @ angus421@home.com for me to explain in more detail, Just one more question, are you living in Markham area, if so, are you mod your car at Optional performence

What octane fuel are you running? In the US you should probably run 92. In europe you need to feed it 98RON octane.

Any lower and it will start knocking under boost. The ECU detects this and one of it's actions is lowering the boost level.

Also bring it back to stock form first.. Just as a baseline measurement.

Bye, Arno.

Rob,

My 99 S70 idles at about 20 psi vacuum - max boost is about 12 psi. Check your mods to make sure you haven't inadvertently lowered the maximum boost.

Good luck,

Chelsea

Max boost is .74 bar (10.6 PSI, I figure) so maybe the gauge is

off slightly (15%). Also, boost is limited in first gear and

you don't always get max boost all the time (it is reduced if

any engine pinging is detected or the engine is running hot, etc.).

You might check all the hoses in the intake system. I've found

one of mine loose at one point.

Also, try disconnecting the battery for a few hours to reset the

ECU. Over time, the ECU "tunes" the engine. I've found that right

after an ECU reset my 98 T5 is quite fast (and is probably making

max boost). After a few miles, it detunes a bit (probably in

response to our North American fuel).

20 psi of vacuum sounds rather high to me. Are you sure the meter is calibrated right?

Assuming your last little diddy says that you have a custom 2.5" exhaust and an HKS blow off valve, assuming your meter is calibrated properly, I am almost certain the bov is part of the problem.

I am almost certain your bov is "leaking" boost. If it isn't the bov itself, the plumbing or an incompatability between the wastegate/egr and the bov is causing a drop in boost.

But like I said, check the meter first, 20psi sounds a little high.