Give Your Honda a MegaJolt
As we all know, Honda makes some of the best, highest quality parts that money can buy. From the beginning, they built their reputation on delivering the most reliable cars still on the road today. We love to put OEM Honda parts in our cars, because we know that they will last. However, these days our classic Hondas are getting harder and harder to find parts for. Support from the factory has almost completely dried up. Sometimes, we don’t have a choice but to buy parts made on the cheap, or parts that may be rebuilt with lower standards than our beloved Honda would have tolerated.
Such is my story. When I was rebuilding the engine in my ’81 Accord, I wanted to leave no part un-refreshed on the engine. My nearly 30 year old distributor was showing signs of wear. My tach was bouncing, and I couldn’t keep a steady idle, no matter how perfect I had my mixture adjusted. So I did what many of us would do, and went for a rebuilt unit. When I got it home, the bearing in it made terrible noises, like it was screaming for it’s own death. I took it back to the store and got a replacement. I opened the box at the store, and the second unit fell apart inside the box. Then my 3rd distributor had the same problem as the first. After 2 weeks of not being able to drive my car due to shoddy rebuilt parts, I decided I was done with distributors.
This is where the MegaJolt Lite Jr comes in to play. It’s a cost effective, open-source, fully programmable, distributorless ignition system. It sounds complicated, but it’s really quite simple enough. You buy the MegaJolt unit from Autosport Labs, source some sensors and electronics from one of the millions of Fords (gasp!) built in the 90s, wire it together, and program your timing with your computer. Ignition timing is perfect, because it uses a toothed sensor wheel mounted directly on your crankshaft, whereas the old Honda distributors were driven by the cam. And the cam of course is driven by a timing belt on the crankshaft. The MegaJolt really has no moving parts other than the trigger wheel, and it never actually touches any sensor, so there’s nothing to wear out.
To source all the components, you need to find a 4-cylinder Ford Escort from about 1990-1993. You can quickly identify them, because they will have a coil pack feeding the spark plugs. The basic parts you will need to make the MegaJolt work are:
- 36-1 Crank Trigger Wheel (Mounted on the crankshaft pulley)
- Crank Position (VR) Sensor (Nearly touching the trigger wheel)
- EDIS Module (On the driver’s side strut tower with a red and white sticker on them usually)
- Coil Pack (Mounted next to the valve cover, opposite the cam pulley)
Going to the wrecking yard to pull all these parts yourself will be the most cost-effective thing to do. However, the trigger wheel and VR sensor can be a real pain to get. So I took the lazy man’s way out and bought a “kit” that I found on eBay that came with everything from an Escort already pulled for about $100 shipped. Alternatively, you can get new sensors and harness pigtails directly from Autosport Labs’ website. Also there are many alternative styles of 36-1 trigger wheels on eBay that may be better suited to installing on your particular application. And most local parts stores should be able to get you a new coil pack, in addition to a number of aftermarket high-performance coils available.
Once you have everything gathered up, the first and possibly the most difficult part of the whole installation will be to mount your trigger wheel and crank position sensor. These two parts work together by telling the EDIS and MegaJolt computers exactly where the crankshaft is in it’s rotation. You can use any steel trigger wheel for this application, as long as it has the 36 teeth with 1 missing (hence 36-1). The only caveat is that you must be sure that the missing tooth is 90 degrees off from where you mount the sensor. (See the install guide for more details.) So you will definitely want to mount your sensor before you position the trigger wheel on your crankshaft.
To mount the sensor on my Accord I utilized 2 unused bolt holes on the back of the block and built a 90 degree bracket. It was imperative that the sensor is within a millimeter or two of the trigger wheel, so I made sure to slot the holes on the bracket where it mounted to the block, and where the sensor mounted to the bracket so that it was fully adjustable.
I initially used this crank pulley (right) that I had pulled off of a 76 Accord at the wrecking yard. I figured it would give me more clearance to mount the trigger wheel on as opposed to the stock 81 pulley (left).
This is how I wound up mounting the pulley. Using a drill press and tapping 3 holes into both pieces so they could be bolted together. Luckily, the Escort’s trigger wheel was exactly the same diameter as the pulley, so it was really easy to keep perfectly centered.
I wound up having to use some spacers to get the trigger wheel out away from the pulley. This was due to clearance issues with the way I had built my bracket and clearance to the alternator belt. But as noted, my bracket was adjustable and this was no big deal.
Here’s how it looks once it’s all mounted up. This is looking down the left side framerail. I know it’s not the best picture ever, but it gives you an idea just how you need to mount sensor in relation to the toothed wheel, and just how close it needs to be. Once you get to this point, the hard part is really over. The rest of the setup is deciding where to mount the rest of the components, and wiring them up.
Now, I know the wiring can look a little intimidating. This is what the mess looked like at one point during my install. But there’s really not much to it. The coil packs have to be wired to the EDIS module, this is only 3 wires. The crankshaft position sensor only has 2 wires (this needs to be shielded wire), and it runs to the EDIS module as well. And then there are two more signal wires that must be shielded that are going from the EDIS module to the MegaJolt. Then you must power the MegaJolt and the EDIS module, and that’s it for the basics.
There is one slight problem, and it’s that the original tach signal used to come off the negative connector on the stock coil. Well, now you technically have 2 coils in your coilpack and your tach won’t know how to deal with that. So there are a couple of quick fixes. The best thing to do is to use zener diodes (as shown in the installation guide) to combine the two coil signals into one. This trick will work to power your fuel pump, as your fuel pump relay needs an actual signal from a coil.
Alternatively, you can hook the “Tach Out” on the MegaJolt or on the EDIS module to your tach. This will work your tachometer just fine, but the signal doesn’t work to kick in the fuel pump for some reason. So you will need a different relay, or you will need to bypass your fuel pump relay.
If you want to get really fancy, there are a couple of other cool features in the MegaJolt setup. To help with drivability, you can wire in a GM engine coolant temperature sensor (available on Autosport Labs site). Using this sensor, you can advance or retard the timing based on the signal received from the sensor. Ideally, you’d use this to advance the timing while the engine is cold to help it run smoother.
Autosport Labs also offers a “Hard Rev Limiter” which is an addon board for the MegaJolt. This can be set to cut the power to the coils at any RPM that you wish. It also adds some “effects” to your exhaust.
In addition, there are 4 user output pins and a shift light pin that can be set up to output 12 volt signals at any RPM you desire. This gives you options for shift lights, or maybe an intercooler sprayer that triggers at certain RPMS. You could trigger relays, or do any number of things with the outputs. My future plans are to have my tach change from green, to yellow at 4000RPM, then red at 6000RPM. Autosport Labs also sells a sequential shift light kit that you can build yourself to hone your soldering skills and add a little bling to your dashboard.
Once you have everything wired up and running, you will need to program your MegaJolt with your optimal ignition timing. The best way is to get your car on a brake dyno so you can get the optimal tune at all RPMs and load levels. The stock map that that it comes with will work to get you running and driving without worry of knocking. So you can drive with it right away and enjoy the benefits. And if you decide you want to do a “street tune,” the MegaJolt comes with some handy datalogging tools so you can find out where your engine is performing it’s best.
When I took on this project, I had never done anything like it before. The most I wiring that I had ever done was perhaps installing an aftermarket stereo and some amplifiers. It felt overwhelming at first, but turned out to be much easier than I thought. You don’t have to be an electronics wizard to use it or wait to get it on a dyno right away before you can use it. Once you get it set up, you sort of forget you’ve got it. You just drive your car every day like you always have.
The power it gives you to fine tune your timing over just adjusting or recurving the distributor is invaluable. The smoothness of the idle is immediately obvious from the first crank over of the engine, not to mention just how much easier the engine starts every time. I think you’ll find a MegaJolt is a nice touch for your classic Honda, and an excellent alternative to an OEM distributor. Be sure to check out my project thread on 3geez.com HERE!
– John Turk