Volvo 850 Made from 1993 to 1997, this Volvo line was available in both a wagon and a sedan, both with were graced with several trim levels.

Another overboost post...

Old 05-16-2019, 02:00 PM
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Join Date: Apr 2019
Posts: 5
Default Another overboost post...

Hello all. I drive a 95 turbo wagon. I have done the PCV, Timing overhaul, PS pump, fuel filter/injectors, cleaned throttle body/idle air/ trans drain, replaced turbo with 16T, all new silicone lines (correctly placed, and a had a high flow CAT put in). I am boosting consistently to 14 PSI with the waste gate adjusted super conservatively. The other day I hit fuel cut off and it scared the crap out of me. Boost does not start until 2300-2500 rpms, but spikes to 14 psi. I have tested the Bypass valve and it hold vacuum but the gauge will slowly go down... Is my wastegate flapper stuck closed, or not opening enough? I have tested the actuator and it moves at very little PSI. I am at a loss as I have tried 2 different TCVS.

95 turbo wagon, RIP kit, EGR, OBD I and II, LTRM fuel trim is roughly +3-4%, average engine temp 195, MPG 18-19 city.

PS, with my TCV unplugged I got 0 boost whatsoever.

Last edited by shawneesnaketail; 05-16-2019 at 02:03 PM.
Old 05-17-2019, 05:01 PM
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Join Date: May 2012
Location: Kingsport, TN
Posts: 1,515

I drive a manual 1998, and I have a compound pressure gage, so it allows me to experiment some, which I did on the way to work this morning. I don't think what you are seeing there about boost coming on fast starting at 2300 rpm is out of line. That sounds reasonable. I can get boost below that, but your car would downshift in that situation. There is definitely not much pressure available below 2000.
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