View Full Version : Question about boost gauge.

07-10-2008, 05:01 PM
Can someone explain to me what I'm supposed to be seeing?

On idle, I'll see about 25" of vac. Then when I push the throttle while driving, it'll spike at about 12 PSI and drop back down to 0 PSI at about 5000RPM. When driving, it hovers around 8 PSI if I keep shifting through the gears. It just seems that the needle jumps all over the place. Is this normal?

07-10-2008, 05:03 PM
It all sounds normal except for it dropping to 0 at 5k. You're still on the gas and it just drops?

07-10-2008, 05:06 PM
Well not really ON the gas. Probably at half throttle. I assumed that as long as I was still giving it throttle, my boost would hold. For example, I'm driving and I shift from 1st to 2nd. In 2nd, I throttle to about 4.5k and hold before shifting. At this point, my boost gauge drops from about 12 PSI to 0, until I shift.

edit: The reason I ask is I just installed my boost gauge today, which I bought used. It came with a kit that contained a vinyl line. After install, my boost gauge was not working at all. Pulled the line and found it was kinked. I've never had or paid much attention to a boost gauge before so I don't really know how it's supposed to act. I fixed the line and the needle was all over the place. I pulled the vinyl line and put a rubber line in. Boost gauge acted the same. Just wanted to make sure the gauge wasn't DOA.

07-10-2008, 05:18 PM
You should really be around -22 in vac max at idle. Maybe -15 on cold start.

Edit to below me: Yeah, I know it should be -20 hg, but my gauge is a little off at times. I said -22 because that is what mine sits at. but when new it was -20 on the dot. -25 while crusing foot off gas.

07-12-2008, 08:45 PM
I typically see it ranging around 20mmHg, or in other words, roughly 9-10psi.

07-12-2008, 08:47 PM
if you have a stock k03, you should see the boost go down after 5k rpm. Also, if you like let go of your gas, you will go back into vacuum.