Turbo Boost Gauge Addition (Electrical Gauge)

[Saab 95]

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Saab 9-5 boost gauge installation Instructions

A turbocharged car without a boost gauge is no fun. It's not that you really need it, but knowing what's really happening with your engine helps a bit, and the pressure surges when you mash the pedal sure are entertaining.
My car was among those unfortunate Saabs that came without a boost gauge (not that the standard one is very useful though), and I long wanted to fix that. Here's a detailed (maybe too detailed) description of the installation process. (And I did wash the engine a couple of days after performing this work ;)

The measurements I'm getting from a 1999 Saab 9-5 2.3t with a low pressure turbo are: the vacuum is 18-20 Hg at idle, 15 Hg while driving, up to 24 Hg when coasting. With the stock engine the boost during the moderate acceleration settled around 5 psi, the highest I've seen at WOT is 9 psi. An ECU upgrade from BSR raised these numbers to 12-13 psi in second gear and 14-15 psi in third.

Click to enlarge!

Cyberdyne Ultragage boost/vacuum gauge kit (part #A213E061Y) bought on eBay. It contains a gauge, a sender, some tubing and other stuff.

I know I could've gotten an analog gauge for half the price, but I'm a digital freak, I like numbers and precision

The sending unit is sealed for good, it has a nipple for the vacuum hose and a signal wire for the gauge

The tees are a buck a piece from your favorite parts store. This one is dirty as I've just tried to fit it on a car

Our primary points of interest today would be the intake manifold and the big fuse box. The engine is filthy, and I'm sorry for that. Should have done the spring cleaning first.

Disconnecting the battery (always a good idea when working with wiring!

Lower dash To find a suitable place to get through the firewall, There are three T25 torx screws holding it.

Remove two more screws, unless you want the cover hanging on the OBD-II connector wires

Look for holes and wires coming through firewall.

Looking from the engine side, the access to one cluster is blocked by the strut tower and the fuse boxes are blocking the other. I pick the fuse boxes.

First, remove the cover from the smaller box

Disconnect Cables: Then unbolt the cables using a 10 mm socket.

Push the latches, and the smaller box pops right up. The bigger box is secured with three nuts -- two are in the open, and the third one is under the master brake cylinder

Move the fuse boxes out of the way and remove another connector assembly (lift the rubber trim to get it out.

The rubber sleeve around the cables is zip tied and wrapped with dirty vinyl tape. We'll get rid of that.

The sender cable is rather soft, so I will use this plastic pipe to get the wire through the sleeve.

After some pushing and wiggling the pipe comes out on the engine side.

Inserting the wire.

and comes out under the dash.....

Find a good way to pass the cable to the top of the dash to the A-pillar and fasten it.

Now we need to find a place to tap for the boost pressure. First, remove the engine cover.

A nipple on top of the intake manifold looks very promising.

There are two hoses coming out of it, and the top one is so inviting!

Tap into this tee.

First, remove one of the old hoses from the tee.

Then connect it to the new tee we prepared during the step 4.

And finally connect the short end of the hose to the original tee.

This piece would be easy to remove later in case you'd want to sell the car. The long end in the right now runs to the sending unit.

Time to connect it to the unit and secure the new hose so it doesn't rub against anything.

Saab 9-5 boost gauge install

Fasten the sending unit well and bolt the fuse boxes back in place. Check if everything is connected properly.

ground nut is right at hand (10 mm again) and the cigarette lighter fuse would donor the power.

Out for a test drive. A healthy 20 Hg vacuum at idle is on display.

Everything is put back together, and the wires are coming out at the base of the A-pillar.

The gauge comes with a memory button. Why haven't they just built it right into the face plate?

Ah, well, an aluminum bracket will do.

Cut the top of a bottle for a pod for the gauge

Painting it inside looked like a good idea.

Luckily, I had some black paint too.

gauge sticks surprisingly tight between the pillar and the dash. It should hold until I find a suitable pod.

It's a bit too bright at night, but we'll adjust that.

Good visibility in the daylight.

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