The first step was too identify how each of the gauges needed to be wired up inside the engine bay and what was the best way of routing the necessary cables back inside the car. Since the boost and digital oil gauges were being mounted inside an A-pillar pod I was looking for the nearest possible hole in the bulkhead. I knew of one that is used by the air-con drain, but that is on the passenger side of the car and just too far from the drivers pillar. Thankfully though, there's an unused hole just above the Downpipe, below the power steering reservoir.
I was a bit worried about using this since there's a lot of heat coming off the Downpipe, so I decided to run any cables inside of some protective flexible tubing.
Step 1 - Remove Intercooler
For my car this first involved removing the strut brace. Use a 12mm socket wrench to undo the 6 nuts holding the strut brace to the top of the suspension towers. Once removed,
- undo the jubilee clips (8mm socket) on large rubber hose connected to the inlet manifold
- undo the jubilee clip (8mm socket) on the Turbo inlet
- undo the large spring clip on the dump valve
- undo the small rubber hose attached to the dump valve
- finally, undo the two bolts (12mm) for the Intercooler bracket
The intercooler should lift straight out (with a bit of coaxing).
Step 2 - Cable Runs
First thing you need to do is to remove the trim surrounding the steering column. Remove the small plastic trim screw, then the two screws hidden underneath the trim (one is just above the bonnet release switch).
Next, gently pull the trim towards you. It is held in-place by three large plastic clips - one too the far right of the dash and one either side of the steering column.
Once the trim has been loosened, you need to disconnect the rear fog light switch (and the driving light switch if your car is fitted with PIAA's or similar lights).
Next, use a flat-bladed screwdriver to loosen and remove the Select Monitor connect from the base of the trim. This should allow the trim to be removed completely.
Finally, remove the large metal bracket from under the steering column by undoing the two bolts (10mm socket).
Now that the trim has been removed, you need to cut a hole in the soundproofing material in the drivers footwell, just behind the hole in the bulkhead (one above the Downpipe). I just used a thin, flat-bladed screwdriver to poke through from the engine bay, then just cut through enough to be able to pass through the flexible conduit.
I used approximately 1.5m of 11.5mm flexible convoluted tubing from Vehicle Wiring Products (ref# F11) for all cables and then run each of the individual cables (Knocklink, oil temp & oil pressure) inside a smaller diameter tube (7mm, Ref# 7F). The 11.5mm tubing was just enough (and I mean a very tight squeeze) for the vacuum hose, Knocklink cable, oil temp cable and the oil pressure cables. If I were to do it again, I'd have used a slightly larger conduit to allow future cables to be run easily. I would have also ordered the split-version of the tubing as it can be easily removed or new cables can be easily added without have to replace anything.
It's also worth mentioning that the SPA wiring is connected to a large 12-pin Molex connector and the other individual wires are connected directly to specific connectors for the senders. This makes it very difficult to run through the bulkhead and impossible to run through any tubing. I decide to dismantle the Molex connector and run the cables from the engine bay into the cabin. The Knocklink has bar wires on one end of the loom to connect to the Bosch sensor in the engine bay, so I had to run this cable from the cabin into the engine bay. The vacuum hose for the boost cable didn't have any connectors attached, so it can be run either way.
Once inside the cabin, I ran the oil temp, oil pressure wires and the vacuum hose up underneath the dash and out through a gap at the bottom of the a-pillar.
I ran the Knocklink wires up underneath the steering column taking care not to interfere with the movement of the steering rack. Use the steering rack adjustment arm to check that the cable isn't being snagged in any way.
Step 3 - Sensors
a. Bosch Knock Sensor
The best place to fit the new Bosch knock sensor is to the bracket on the passenger side of the engine block. Remove the existing bolt (M8x20mm) and fit the new sensor using a new M8x30mm bolt. Depending on the amount of give on the rubber hose attached to the bracket, you can either fit the sensor on top of the bracket or re-fit the bracket on top of the sensor.
Next connect the Knocklink wires to the Bosch Jetronic connector. The Knocklink manual states that you should check which pin is ground by performing a continuity check on the sensor. This doesn't work and I've been informed that the manual is incorrect for this type of sensor and it doesn't matter which pins are connected to which wires.
I wired the Brown => Pin#1, Black => Pin#2 and mine works fine.
b. Oil Temp Probe
After taking some advice from other people on the Scoobynet BBS, the consensus seemed to suggest that the best place to take the Oil temperature reading was above #3 cylinder as this tended to be the hottest part of the engine. One other option would have been the sump, but I was told that readings from here can be affected by airflow running under the car. As luck would have it Subaru have kindly left a bung as if meant for such a sender ;-)
The OEM bung has an 8mm hex hole, but since it can be in pretty tightly I would recommend using a hex socket, long extension bar and a sturdy socket wrench to remove it.
Unfortunately, the SPA temp probe (1/8 NPT) is a smaller thread than the OEM bung (M18x1.5), so an adapter is required. I sourced my adapter (part# LMA067) from Le Mans Motorsport and it cost less than £4.
Take care once the bung is removed as you now have the top of cylinder #3 exposed to the elements and it won't take kindly to any debris that happens to fall inside.
Fit the adaptor using plenty of PFTE on the threads. I used a large 22mm socket, extension bar and a torque wrench (set to 35lb/ft) and this gave a good seal. Then fit the temperature probe using a 13mm spanner. This can be a bit tricky since there isn't much room. Again, use plenty of PFTE on the threads to give a good seal and then connect the wires for the SPA gauge.
c. Boost
Again, Subaru have provided a feed for the vacuum pipe on top of the manifold. Simply remove the rubber bung to expose the vacuum pipe nipple.
Unfortunately, the Autometer vacuum tubing (3mm external diameter) is too small to fit directly onto the nipple, so I needed to use some additional vacuum tubing with a 3mm bore. I attached this to the nipple on top of the manifold and secured it with some cable ties, then inserted the Autometer tubing into the larger tubing and secured it with some more cable ties.
At this point I connected the other end of the vacuum tubing to the Boost gauge in order to check everything was OK and that there were no air leaks.
d. Oil Pressure Sensor
The OE Oil Pressure sensor is located on the engine block underneath the Alternator. The simplest method for replacing this is to remove the Alternator itself.
First you need to remove the alternator/aircon belt shields. Unscrew the 3 bolts (10mm) and lift the shields out to expose the belt.
Next remove the long bolt used to adjust the alternator belt and the smaller bolt beneath. Then remove the large bolt holding the alternator in-place. Remove the alternator belt, then with some coaxing the alternator should pivot up and to the right, before lifting completely out.
Now disconnect the electrical wire from the OE oil pressure sender, then remove it using a 23mm spanner. The sender is already fitted to an adaptor. Don not remove this, just the sender itself.
Now install the SPA oil pressure sender.
Simply re-fit the alternator, belt and adjust it's tension until you can only twist it between 45 and 90 degrees using two fingers.
Step 4 - Re-fit Intercooler
Simply reverse the steps taken to remove the intercooler.
Step 5 - Test for Oil Leaks
Now that you fitted the new Oil temp probe and pressure sender, it's a good idea to check that they are sealed properly and won't leak. I started the car and let it idle for a good 10mins and constantly checked both for any signs of oil. Then I took the car for a short 10min drive to build up some pressure and temperature.
I also listened for any air leaks from the Boost gauge and checked that it was showing the correct readings.
Thankfully everything was OK.
Step 6 - Electrical supply
a. Common Ground
Since the cars chassis is connected to the negative terminal of the battery, all you need to do is find a suitable place on the cars body to attach all the ground cables too. Thankfully, there are a few ground points under the dash, but I decided to use on located directly under the steering column.
I simply trimmed the cable from the Knocklink to a more suitable length (shorter the better for ground cables) and ran two seperate wires (1mm2) up under the dash to the A-pillar. This is for the Autometer boost gauge bulb and the SPA digital gauge.
I connected all three ground wires to a 6.4mm ring terminal and used the existing bolt under the dash to secure it. The Knocklink and SPA digital wires are pre-connected to the connector blocks, but I used a blade connector for the Autometer boost gauge bulb connection.
b. 12v Switched Illumination Supply (i.e. only on with lights)
I searched around on the Scoobynet BBS to find an idea of where to take the illumination feed from. Most suggested the Fog Lamp switch as this is the closest to the A-pillar.
I was reliably informed that the 'purple wire with grey flecks' was the correct one and a quick test with my digital multi-meter showed that this wire is hot only when the ignition AND lights are turned on.
I used a connector from Vehicle Wiring Products (part# C952) to tap into this wire. I then used the corresponding blade connector (part# PRU1211) and ran a wire up to the A-pillar. I used another blade connector for the connection to the Autometer Boost Gauge bulb.
Note: The Autometer bulb can only be wired one way and the 'hot' wire MUST be connected to the White wire on the bulb.
c. 12v Switched Supply
Finding an appropriate 12v that is hot when the ignition is started proved a little trickier than I expected. The majority of people use the cigarette lighter wire and this seem ideal as it wasn't far from the left-hand side of the steering column where I wanted to fit my Knocklink display. Unfortunately, to gain full access to the cigarette lighter connector you need to dismantle most of the dash.
The dash trim surrounding the heater controls and stereo is removed in one piece, but you need to remove the stereo first. On my car I've always had problems re-fitting the stereo unless I remove the glove box and the centre console trim as this then allows me to keep all the wires behind the stereo out-of-the way as I slide it back into the dash.
So, I chose the hard route and dismantled the centre console, the glove box and the dash trim. All for a single wire :-(
First remove the gear knob, but rotating anti-clockwise until it comes loose from the gear stick. Then just pull it off of the leather gaiter.
Next, lift the arm rest cover and remove the two screws on top of the handbrake trim. This should allow the trim to be pulled upwards. Take care as the electric window controls will be attached to this piece of trim. Disconnect the controls and remove the trim from around the handbrake.
Gently (but firmly) pull up on the gear stick surround and the trim should pop straight off.
Remove the 5 screws holding down the main centre console trim, then lift the whole thing straight out.
Now remove the plastic screw to the far-right of the glove box. Then remove the 2 bottom screws and the 3 inside the glove box itself and it should drop down. Note: Take care not to overstretch the Sigma alarm keypad cable.
To remove the heater control surround, you need to remove the stereo first. I have an MP3 display where the ashtray usually sits, so I removed that too. I also removed the cigarette lighter, but I didn't know any better :-)
As with any part of the trim, you need too be gentle as well as firm. You keep thinking it's going to break, but so far everything's survived. Pull from the bottom first, then as it pops free, move up each side releasing each clip. The tricky part is the two clips along the top of the trim (directly below the vents). These can be pretty tight, so you need to pull with reasonable force. If anything's going to break, it's these clips so be careful.
Disconnect the headlamp adjustment switch, the bright switch, the headlamp washer switch and finally the connector for the cigarette lighter. This should allow the whole trim to be removed.
Locate the yellow/red cable and tap into this. The SPA digital gauge has an in-line fuse on the 'hot' wire. I connected this too the tap, then cut the cable from the SPA gauge connector to create a short piece of wire with just the tap blade connector, the fuse and a blade connector at the other end. I then ran all the 'hot' wires (SPA gauge & Knocklink) together and terminated them with the female blade connector, so I could connect them to the in-line fuse cable.
Step 7 - Re-fit trim
You can now replace all the trim you've just spent ages removing, including the dash trim, centre console, glove box and the steering column trim (not forgetting the large metal bracket). All this just to run one measly little cable :-(
Step 8 - Mounting the gauges
Now that the electrical supply and the sensors are in-place, you can mount the gauges.
a. Knocklink
Since the engine is more prone to detonation on high-revs or under a high load you are more likely to be busy driving the car and will never notice the Knocklink LED's flash if it's not in your line of sight or peripheral vision.
For this reason I decided to mount my display to the left of the steering wheel, just above the lights/indicator stalk. You can see from the pictures detailing the wiring run for the knock sensor how I ran the cables behind the steering wheel (making sure it didn't get caught when adjusting the steering wheel height). The Knocklink has some 3M double-side sticky tape attached to the rear of the display. The cable was pretty tight, so it wasn't that loose, but the tape is enough to hold it in the right position and can be clearly seen through the steering wheel.
b. SPA Digital Oil Temp/Pressure & Autometer Mechanical Boost
As I've already mentioned, I decided to mount the two 52mm gauges on the A-pillar. J-Spec provided a fiberglass double a-pillar pod that matches the trim perfectly.
I wondered what was the best method of mounting this type of pod since it's design to fit over the existing trim and is not a direct replacement. When I tried a dry-fit, the bottom of the trim can be pushed into the small gap between the dashboard trim and is held in tightly. There's nothing holding it on at the top, so I considered some double sided tape. Then I noticed the alarm sensor is screwed into the trim and this would need to be moved and re-attached to the a-pillar pod.
Then I hit on the idea that if the screw was long enough and I took time to align the pod, I could drill a small hole and just screw the sensor to the new pod and into the existing hole in the OE trim. That way, if I ever remove the pod it won't have left any unsightly holes or marks.
The SPA digital gauge comes with either a black or chrome bezel, so neither matches the matt silver finish of the Autometer boost gauge. I decided to spray both bezels the same shade of silver and bought a small spray can of silver hobbyist paint from my local Homebase. The paint was a pretty good match for the Autometer bezel and I couldn't really tell that it made a difference. The SPA gauge at least matches perfectly now.
Mounting the gauges in the pod itself is pretty straightforward. The Autometer is supplied with a wide rubber-band which fits around the gauge and holds it snugly inside the pod without have to use the U-shaped mounting bracket.
Unfortunately, the SPA gauge only has a rubber o-ring to lessen vibration and needs it's mounting bracket to hold it securely inside the pod. This makes it a right pain to fit and leaves even less room to access the large 12-pin Molex connector on the rear of the gauge.
Since I disassembled the Molex connector, I need to insert all the pins back into the connector and then it's just a matter of plugging this into the rear of the gauge.
I had to drill a small hole (6mm) in the pod to mount the switch for the SPA digital gauge.
With the Autometer boost gauge I had to terminate the bulb wires with some blade terminals. I used a female blade on the 'hot' wire (white) and a male blade on the ground wire (black) so they couldn't be wired incorrectly.
The vacuum pipe needs to have the end-cap fitted first, then the small ferrule (this is a compression fitting to hold onto the tubing). There is also a brass adaptor that needs to be fitted to the rear of the boost gauge. Then the end-cap can be screwed (10mm spanner) onto this adaptor. I used plenty of PFTE tape on all the threads too make an air-tight seal.
Once all the cables were connected, it was a little awkward mounting the a-pillar pod as the cables take up quite a bit of the gap between the dash and the OE pillar. It all fits, but just takes a little coaxing and patience. I made sure the wires and tubing were inside the pod and pulled some of the slack from under the dash.
The it was just a matter of screwing the alarm sensor through the pod and through into the OEM trim for a nice snug fit. Here are some pictures of the finished article:-
As I've already mentioned, I decided to mount the two 52mm gauges on the A-pillar. J-Spec provided a fiberglass double a-pillar pod that matches the trim perfectly.
The SPA digital gauge comes with either a black or chrome bezel, so neither matches the matt silver finish of the Autometer boost gauge. I decided to spray both bezels the same shade of silver and bought a small spray can of silver hobbyist paint from my local Homebase. The paint was a pretty good match for the Autometer bezel and I couldn't really tell that it made a difference. The SPA gauge at least matches perfectly now.
