1995 Volvo 850 T-5R Boost gauge reading, am I low?

Post by **rspi** » 04 Apr 2014, 09:55

The other day my car experienced some new found power. All of the sudden I have some real boost. I assumed that I was "overboosting" and took it easy for the most part. A few time I did put my foot in it carefully to see what it was doing and it was going about 90% into the white area of the stock gauge. Usually mine would boost about 30% into the white area.

The next morning I turned my ScanGauge to the HP setting and checked the reading on it. Usually I don't see over 170 HP on the gauge, this time it spiked at about 258 HP. So, I switched the performance button to E and checked under the hood for broken vacuum lines etc. None found. Well, before I knew it, it was back to "usual", not sure if it's "normal". Someone suggest that I may have a problem with my wastegate and that the car "was" performing normal for a short time (for an R). What do you guys think?

If you have a or have had a T5 and had experience with these stock gauges, post your experience and let me know what you think.

Photo at WOT, peak boost at about 75 mph.

: Stock Volvo 850 Boost Gauge; Boost_V.JPG (15.03 KiB) Viewed 1921 times

Short video showing WOT while driving 65 mph.

Post by **rspi** » 05 Apr 2014, 20:33

Bump...

Post by **northernlights** » 05 Apr 2014, 21:13

Until I replaced my compressor bypass valve (CBV) diaphragm I had erratic boost control that kept getting worse. It's an easy check. If the can doesn't hold vacuum, it need replacing. It's annoying to get to the fasteners, but it can be done with the turbo on the car.

Even at it's best the boost control seems twitchy on these cars, probably because the ECU doesn't really know the exact boost pressure, but instead targets airflow. I'm working to calm mine down...