View Full Version : unstable boost problem

05-07-2002, 01:24 AM
I've had a boost problem with my sr20 that I always thought was caused by either by the crappy mig-welded bov flange on the car or my turbo xs manual boost controller. In 2nd and 3rd gear, boost would spike to 12 psi and then instantly leak down to 9 psi. 4th would be a little better and 5th gear take me to a solid 14psi. 1st gear won't even boost past 10 lbs. This is with the boost controller set at the same level. Now that I've replaced the bov with a pipe and installed a profec b boost controller, I still can't seem to tune the "hunching" out with it - no matter where the balance knob is, the problem is still there. My idle is rock-solid at 850, and vacuum is just as steady. Also, anything from stock boost to 9 lbs holds pretty well. I'm thinking there's a pinhole leak in the ic piping that is causing this, but if that were true, why am I able to hold boost that much better in higher gears?

The only other thing I semi-suspect is that my knock sensor wire is disconnected, so my next stop is to check the ecu for fault codes (c.e.l. burned out) and then check for boost leaks. For now I wanted to post this to see what other great minds think.

much appreciated-


[ 05-07-2002, 02:26 AM: Message edited by: mTom ]

05-07-2002, 07:46 AM
It seems that the Wastegate is at fault...could be a weak spring...or messed up diaphram (sp?).
Without the BOV, do you hear the wastegate flutter when you lose boost?


05-07-2002, 10:56 AM
No, the wastegate doesn't flutter when I lose boost.


05-10-2002, 10:39 PM
My sr does the exact same thing! I was thinking it could be the lines for the boost guage that are leaking. What kind of guage are you using and how are your lines connected?

05-10-2002, 11:40 PM
bump! http://www.freshalloy.com/

05-11-2002, 12:49 AM
make the lines to the ebc as short as posible.

05-13-2002, 11:11 PM
The lines to the boost controller are the same length as on my friends car with the same setup, but he can hold 14 psi in the lower gears. My Autometer boost guage has its line T'd into the fuel pressure regulator, along with the vacuum line that goes to the back of the boost controller. I don't know if I should suspect a boost leak, because boost holds fine in higher gears. As far as I understand, 10 psi is the same amount of pressure in any gear or vehicle speed, correct? It still feel like I'm overlooking something. Why exactly are dyno pulls generally done in higher gears?


[ 05-13-2002, 12:13 PM: Message edited by: mTom ]