MSD DIS-2 Ignition
Why, might you ask, did i spend the money on an upgraded ignition instead of a bigger turbo, intercooler, or full 3" exhaust. Well, it's simple: Make the car run as well as possible before adding "Big Power" items such as those listed above. Sure, a new turbo would give me a substantial boost in power, as would an intercooler, but if the car isn't running well, what good is it?
I've been bothered by a miss, of sorts, for as long as i've had the car. I've replaced just about everything that could be done to alleviate this problem, but to no avail. In searching for the possibility that it could be a bad spark, i've installed Denso's incredible Iridium plugs and the stout Magnecor 8.5mm spark plug wires, as well as a newer coilpack from a 2.2NA engine. So far, no change, but i haven't hurt anything either.
After talking to a few people from LegacyWorks and the i-club, i decided to look into upgrading my ignition system to see what i could get our of it. MSD's DIS products seemed to be a popular choice and the results were intriguing.
MSD has been around for a long time, and their trademark and name come from an ingenious and straightforward technology, Multiple Spark Discharge.
MSD's technology does 3 very important things different than your stock ignition:
First, it will fire up to 12 individual sparks over a 20 degree crankshaft rotation below 3000RPM. This is much more and much longer duration than any stock system i'm aware of. What it does is burn more of the fuel injected into the cylinder. This in turn creates more horsepower, better gas mileage and reduced emissions.
Second, above 3000rpm it's hard to discharge more than one spark per rev, so instead, it keeps one long, hot spark burning for that same 20 degrees.
Third, with a "diamond" coilpack from a newer Subaru, the extra spark power the ignition serves can be enhanced by the better coil. The DIS increases the spark energy much more than the stock system so that the spark is much hotter and can burn the air-fuel mixture much more completely. Note: A 2.5RS coilpack is NOT necessary, any pack with the "Diamond" logo on it will work better than the earier ones. Any 95+ 2.2 or 2.5 should have these.
The DIS-series ignitions from MSD are meant for distributorless ignitions like those found on most new cars. These cars use a cam or crankshaft sensor to tell the ECU when there should be a spark, instead of using a gear-driven distributor.
The DIS-2 is meant for 4-cylinder DIS cars. There are also versions available for 6 and 8-cylinder cars as well as a High-Output version of the DIS-4. The HO is probably only apropriate for racing applications, however.
I decided to get a DIS-2 based on a lot of positive information i'd found on the 'net, as well as personal recommendations from other Turbo and NA Legacy owners. It's a bit pricey at just over $300USD, but if the claims of increased torque, gas mileage and better emissions was true, it would be worth it. Besides, i've got a nagging miss that i'm hunting down, and the ignition system was the next place to look.
The DIS-2 basically acts as an ignition amplifier, and replaces nothing in your existing ignition system. It's basic setup involves redirecting the signal sent normally right to the coilpack, amplifying it and sending it to the coilpack. Three wires are the minimum that need to be cut, and the unit itself needs to be wired directly to the battery or to a very strong terminal and ground.
The DIS-2 comes with a very good installation manual. Read through it at least once to familiarize yourself with all of the necessary steps and procedures that need to be followed. Refer to it if you get stuck.
Look for a 3-wire connector going to the coilpack. Strip back the harness cover and find a mid-point between the connector and as much as you can unsheath from the harness. Don't cut past the connector on the coilpack!
Disconnect the coilpack, and with the car ignition turned on, but not the engine running, test and see which wire gives a positive voltage. There will be only one, the other two should be inactive. Remember this wire, it's the most important. On my 93 Turbo, it was the middle yellow wire.
Time to operate.
Begin by disconnecting your battery. DC charges are nasty, and we wouldn't want you frying your ECU by any chance.
Cut the positive wire first, and following the guidelines in the manual, connect the appropriate wires to the DIS-2 wiring harness. These should be the red and brown-red wires.
The other two wires will be referred to as channel one and two in the manual. Since my + wire was the middle wire in the harness, i had no way of figuring out which should have been 1 or 2. Since Subaru and most DIS ignitions fire on the intake and exhaust cycles, it really shouldn't matter which is connected to which. I took a chance, connected everything and it works very well. If you encounter a problem after install with it running poorly, it might be wise to try reversing them.
After you've successfully wired the coil, insert the bypass plug into the DIS harness, connect the battery and attempt to start your car. It should start up and run like it did before. If not, check all connections and try again. If it works, you're ready to wire up the DIS-2 itself.
I wired the positive and negative lines directly to the battery itself, with the turn-on line connected to a key-on fuse in the fuse-box in front of the washer fluid box rated at 20 amps.
Double-check all connections, plug the harness into the DIS-2 and give it a shot.
Potential problems at this point are probably related to bad wiring, a bad connection for your key-on lead, or the unit itself. My car ran OK with the positive wire connected incorrectly when just using the harness, but when i connected the DIS-2, it ran horribly. Go back an make sure everything is connected well and try again.
The Legacy doesn't have a ton of space to mount the unit, so i took a tip from Matt Watters and put it right between the strut tower and firewall on the driver side. I had to reroute a few ground wires and a washer-fluid line, but it fits very well. A few self-tapping scres and a bit of cushioning below ensure it's not going anywhere.
The DIS-2 is very sturdy and will take heat, bumps and moisture in stride, though don't push it.
In reading through the manual, you no doubt found information about all of the cool features the DIS-2 has available. Rev limiting, timing retardation and other features make it a very tuneable setup for racers, but it works just fine with factory settings.
A word of note, though it can set your rev limit higher, it can't override your stock limiter, which should be close to 6500rpm. This limit is initiated in the ECU and the DIS-2 doesn't do a thing with the ECU.
One interesting feature that can be set up easily is the startup defeat, which basically disables the DIS-2 when grounded. Simply wire a switch somewhere to ground the wire and the car can't be started, period. Nice theft deterrent, eh?
Ok, so was the $300 bucks, sweat and efford worth the investment? Only you can know for sure, but my initial impressions were a smoother idle (save for that annoying misfire), a bit of extra torque at the low end, fast revving after the turbo spools, and a redline-pounding top end. I've smacked my redline with this automatic a number of times now, at 11 and now 13PSI. It just pulls HARD now.
Fuel economy is one of those things that takes time to actually see results from, but i just got 300 miles out of my last tank of gas, and that's with about 1/2 highway and 1/2 urban driving, with occasional spirited bursts in the city. It's definitely gone up at least a little.
After several months of driving, i'm thoroughly convinced that this is a worthwhile upgrade. Mileage has consistently been 18-19, and many of those miles are not easy-going. This is of course with 11-13PSI, which normally bring mileage down.
I'm %100 satisfied with this unit. As a single upgrade to any ignition system, it should make an immediate difference to anyone familiar with their cars' demeanor. If you're looking for something to make a difference, this is definitely one item that should be on your list.