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 see the next picture
17.04.2004: The kit
A Cyberdyne Ultragage boost/vacuum gauge kit (part #A213E061Y) bought on eBay. It contains a gauge, a sender, some tubing and other stuff.

 

Click to see the next picture
17.04.2004: The gauge
I know I could've gotten an analog gauge for half the price, but I'm a digital freak, I like numbers and precision ;).

 

Click to see the next picture
17.04.2004: The sending unit
The sending unit is sealed for good, it has a nipple for the vacuum hose and a signal wire for the gauge.

 

Click to see the next picture
17.04.2004: The hose
The tees are a buck a piece from your favourite parts store. This one is dirty as I've just tried to fit it on a car.

 

Click to see the next picture
17.04.2004: The engine
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.

 

Click to see the next picture
17.04.2004: Disconnecting the battery
Always a good idea when you're planning to mess with wiring.

 

Click to see the next picture
17.04.2004: The lower dash
To find a suitable place to get through the firewall, remove the lower dash cover. There are three T25 torx screws holding it.

 

Click to see the next picture
17.04.2004: OBD-II connector
Remove two more screws, unless you want the cover hanging on the OBD-II connector wires.

 

Click to see the next picture
17.04.2004: Holes in the firewall
A sysadmin would be shocked by a sentence like this ;). In our case in only means there are two clusters of wires coming through the firewall.

 

Click to see the next picture
17.04.2004: Fuse boxes
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.

 

Click to see the next picture
17.04.2004: Small fuse box
First, remove the cover from the smaller box.

 

Click to see the next picture
17.04.2004: Disconnecting the cables
Then unbolt the cables using a 10 mm socket.

 

Click to see the next picture
17.04.2004: Removing components
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.

 

Click to see the next picture
17.04.2004: Almost there
Move the fuse boxes out of the way and remove another connector assembly (lift the rubber trim to get it out).

 

Click to see the next picture
17.04.2004: The cable sleeve
The rubber sleeve around the cables is ziptied and wrapped with dirty vinyl tape. We'll get rid of that.

 

Click to see the next picture
17.04.2004: A handy pipe
The sender cable is rather soft, so I will use this plastic pipe to get the wire through the sleeve.

 

Click to see the next picture
17.04.2004: The engine side
After some pushing and wiggling the pipe comes out on the engine side.

 

Click to see the next picture
17.04.2004: Inserting the wire
The wire goes in...

 

Click to see the next picture
17.04.2004: Coming through
...and comes out under the dash.

 

Click to see the next picture
17.04.2004: Pipe removed
Find a good way to pass the cable to the top of the dash to the A-pillar and fasten it.

 

Click to see the next picture
17.04.2004: Engine cover
Now we need to find a place to tap for the boost pressure. First, remove the engine cover.

 

Click to see the next picture
17.04.2004: Cover removed
A nipple on top of the intake manifold looks very promising.

 

Click to see the next picture
17.04.2004: Front view
There are two hoses coming out of it, and the top one is so inviting!

 

Click to see the next picture
17.04.2004: Side view
It usually is not a good idea to cut the hoses on a car, and fortunately there's a conveniently placed tee we could tap into.

 

Click to see the next picture
17.04.2004: Removing the hose
First, remove one of the old hoses from the tee.

 

Click to see the next picture
17.04.2004: Old hose to new tee
Then connect it to the new tee we prepared during the step 4.

 

Click to see the next picture
17.04.2004: New hose to old tee
And finally connect the short end of the hose to the original tee.

 

Click to see the next picture
17.04.2004: Lots of hoses
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.

 

Click to see the next picture
17.04.2004: The sending unit
Time to connect it to the unit and secure the new hose so it doesn't rub against anything.

 

Click to see the next picture
17.04.2004: Pulling the wire in
Pull the remaining cable through the sleeve leaving only a short end. Seal the sleeve with a new ziptie and some tape.

 

Click to see the next picture
17.04.2004: Securing the unit
Fasten the sending unit well and bolt the fuse boxes back in place. Check if everything is connected properly.

 

Click to see the next picture
17.04.2004: Connecting the wires
The gauge needs the ground and the 12V power. The ground nut is right at hand (10 mm again) and the cigarette lighter fuse would donor the power.

 

Click to see the next picture
17.04.2004: Test drive
Out for a test drive. A healthy 20 Hg vacuum at idle is on display.

 

Click to see the next picture
17.04.2004: Wiring done
Everything is put back together, and the wires are coming out at the base of the A-pillar.

 

Click to see the next picture
17.04.2004: The gauge
The gauge comes with a memory button. Why haven't they just built it right into the face plate?

 

Click to see the next picture
17.04.2004: Button installed
Ah, well, an aluminum bracket will do.

 

Click to see the next picture
17.04.2004: Plastic bottle
I didn't get a pod for the gauge, and now I didn't want it dangling on its wires while I'm driving in search for one, so I cut the top of a plastic bottle.

 

Click to see the next picture
17.04.2004: Masking tape
Painting it inside looked like a good idea.

 

Click to see the next picture
17.04.2004: All black
Luckily, I had some black paint too.

 

Click to see the next picture
17.04.2004: Mounted
The wires are connected, and the gauge sticks surprisingly tight between the pillar and the dash. It should hold until I find a suitable pod.

 

Click to see the next picture
17.04.2004: Night
It's a bit too bright at night, but we'll adjust that.

 

Click to see the next picture
18.04.2004: Day
Good visibility in the daylight.

  [return to index]

 

 

 
Copyright © 2000-2013 Dmitry Platonoff
All rights reserved.