Megajolt Install on L28 & 3x DCOE

[Lazeum]

Just wanted to share my little ignition winter project. I wanted to keep my triple carbs but I wanted better ignition. I'm sure it would also come with better emission which is also a good point.

 

Here’s the car : ’72 240z with 2.8L L28 engine coming from a 280zx.
I'm converting it to Megajolt this winter during snow (& salt) season.
I've tried to be exhaustive with my presentation.

Only big advice I've got: Get good crimping tools! You must invest in one pair of pliers at least. I've got 3: one for moley pins, 2 for regular flat pins.
I would discourage anybody who would intent this process with regular pliers.








The engine is a "Hot" street L28, expected to have low & mid range torque:
- Head milled, ported, polished, unshrouded, combustion chambers CC’ed, new valve seats, Dual lub systems (internal in cam + spray bar) made by Braap.
- Cam with asymmetrical profile from Rebello Racing with adequate springs, rockers, etc.
- Bottom end is new also with new pistons, rings, bearings, HF oil pump, etc. Compression ratio is around 9.0:1 / 9.5:1.
- 3x Weber 40DCOE with ported Cannon intake. Each runner is linked with the others with a canal to balance pressure between them.
- 6-2-1 MSA coated exhaust header + custom 2,5†exhaust
- Soon to disappear Mallory Unilite distributor

I’m in process of converting the car. Wiring is almost done, I now need to focus on mechanical installation.

I’ve chosen to run MJLJ with TPS option but I don’t exclude to convert it to MAP later. We'll see how it runs first with TPS.

For TPS, I’ve picked one up from a BMW 323ti (E36). The TPS does not have any spring loaded control, its shape for the shaft is easy to reproduce (a round ø8mm shape with one flat) & it is easy to get at any junkyard. Only concern would be that it is not water tight. I got it in Europe for 15€ with the entire throttle body (people get rid of it for better 325i unit)

I also got the one from Autosportlabs webshop but it is big, spring loaded with complex shaft print, so I won’t use it after all.

Regarding install, I’ve installed MJLJ box on the sidekick panel on passenger side with a relay support + fuses.

I’ve made a wiring diagram based on info from the Autosportlabs “how to†section & from one chart found on this board. Only difference is the way I expect to power up the EDIS coils. I’m going to plug the +12V source from the coil + side since the tach is triggered this way.

 

This wiring diagram is good for pre-72 Z, others would likely needs the tach adapter & other type of wiring since Tach changed in 73.

All wires are crimped with proper tools. When wires needed to be connected together; I’ve twisted them together, soldered them & protected them with shrink tubes.
Wires are all protected with high temp hoses under the hood.



For VR sensor, I’ve made a CAD model of the front of the engine to design a support. Support, in aluminum, is made with a CNC machine. I’ve taken into consideration some margin for adjustability.
The drawback from the support is I need to ditch the stock fan & go with e-fan instead. I wanted to do it anyway so I did not bother…





36-1 wheel is coming from the EDIS car donor. Crank damper has been machined to be slightly smaller than the wheel. I cannot feel any play but wheel can rotate freely around the pulley.
The plan is to install the VR sensor, get the wheel in front of it accordingly, get a mark done & spot weld the wheel in place (hopefully the weld will not hurt the rubber, I’ll be careful about that).
I would have to redo it, I think I would choose to pressfit the wheel instead of welding it but it is too late.

EDIS coils have some rubber pads installed to avoid vibrations. Pads also raise the coils allowing me to get it install on a flat surface without any specific support. Pads are male/male type with ø20 OD. I had to make a thread on each Coil support hole with Helicoils to make pads fit.



TPS will be mounted on carbs rod linkage instead on carb shaft. My DCOE are the old style, there’s no hole on housing to install easily a support for TPS.
Drawback with the way I expect to install TPS is that I won’t have 90° angle between idle & WOT but around 45-60°. Hopefully TPS resolution / sensitivity will be sufficient.
The support will be a very simple steel plate design bent, nothing really fancy. Still need to design it and make it.

To finish the first post, here's how my install looks like for now (or almost, wires have been setup, I don't see anything anymore from the driver side)




The next steps would be to try the new support, check 36-1 wheel position, get the wiring finished under the hood and install EDIS components.

Edited October 24, 2013 by Lazeum

[Leon]

Very nicely done, you're off to a GREAT start!

 

One tip: run it on EDIS in limp-mode before hooking up PIP and SAW signals, to make sure the install is ok before getting MJLJ involved.

[winstonusmc]

Cool sTuff. I did something similar on my 240z with a full MS3, its a thread here in this forum. I am not going to stay spark only on the MS3 though because I have a L28ET going in now. I thought it was kinda odd you are using a TPS on this setup. I found it a ton easier to put a MAP sensor in instead of a TPS and almost all OEMs use MAP as load. Good stuff though. I can share my map for you, it runs really well on my L26, you would just have to tweak it for the L28.

[rayaapp2]

I would be interested in your Megajolt curve information!

When you get to that point at least. It would be a good starting point for my L28 at least.

Great start and very cool!

 

 

 

Cool sTuff. I did something similar on my 240z with a full MS3, its a thread here in this forum. I am not going to stay spark only on the MS3 though because I have a L28ET going in now. I thought it was kinda odd you are using a TPS on this setup. I found it a ton easier to put a MAP sensor in instead of a TPS and almost all OEMs use MAP as load. Good stuff though. I can share my map for you, it runs really well on my L26, you would just have to tweak it for the L28.

 

Or yours winstonusmc, that might work to lol

Edited December 16, 2012 by rayaapp2

[Lazeum]

Thanks for the comments  . The goal is to have a trouble free operation. We'll see how it goes...

 

Regarding EDIS, I'm still thinking about how to get 10° exactly. VR sensor & 36-1 are not going to be perfectly aligned so I'm expecting an offset there. 

MJLJ or MS can adjust the offset but can it be done with EDIS alone? I'm quite sure, not.

I've added some adjustment also for this matter on the VR sensor mount.

 

For information, I was short on shielded cables for VR sensor, I found some for microphone, very cheap (1 meter = 1€).

Edited December 16, 2012 by Lazeum

[Leon]

Thanks for the comments  . The goal is to have a trouble free operation. We'll see how it goes...

 

Regarding EDIS, I'm still thinking about how to get 10° exactly. VR sensor & 36-1 are not going to be perfectly aligned so I'm expecting an offset there. 

MJLJ or MS can adjust the offset but can it be done with EDIS alone? I'm quite sure, not.

I've added some adjustment also for this matter on the VR sensor mount.

 

For information, I was short on shielded cables for VR sensor, I found some for microphone, very cheap (1 meter = 1€).

 

You're correct, Megajolt has a trigger offset option. Up to 10deg from what I remember, but it takes away from total possible advance (not like you'll be running 50deg BTDC anyway).

[Lazeum]

Where should be the tooth on the 36-1 wheel relative to VR sensor? Should they be centered, in front of each other? should the VR sensor on the edge of the tooth instead of in the center?

 

By default, I will shoot for everything aligned and centered but maybe I'm wrong...

[Leon]

Center it and adjust accordingly once it's running. Just do it by the diagram in the MJ install guide.

[Lazeum]

ok, thanks, will do

Not much to see yet but EDIS6 controller is in the car, installed with the remaining harness.

I just need to install the VR sensor, solder the wires, weld the wheel & it should be almost good to go. Xmas vacations should be interesting

[Lazeum]

During vacations, I was able to finish the project. I haven't started the car yet but the system reacts with the sensor & everything is done.
Here are some pictures of the sensors & other EDIS components installed inside the car.

The support made for VR sensor is installed & working as it should.

 

The 36-1 wheel has also been welded to the crank pulley. I was afraid about heat that could have damaged the rubber part of the damper. So I've been careful about that. The wheel & damper are massive enough to dissipate the heat enough without any problem. The part was barely hot to the touch.
I still need to sandblast the part & paint it to look good before final installation.



I also installed the coils on the fender of the car. The location chosen is the one where the 4 points from the coils are in contact with the car body. So it is not 100% straight but it is the only way without any extra support to locate it properly.



To power the coils, I took a 12V source from the original coil. To leave the original harness in place, I soldered an extra wire under the dash. The wire is Black w/ white stripe. I also need to tap together the 2 sides of the ballast resistor no longer needed with Megajolt.

 

Finally I've finished TPS install with a support made in 0.5mm thick steel plate.

 

When I plugged my laptop to the MJLJ, I can read what's inside, I can calibrate my TPS to read 0 / 100% (but I don't see the area moving that much on timing map - engine might need to run for that) & setup everything accordingly.

I need custom spark plug wires to finish the install which is now complete. I expect to run the car only in spring, I need to fix my fuel tank first. It is contaminated & fuel lines are getting clogged each time I drive the Z.

[Lazeum]

I realize that having my coilpack plugged on +12V from original coil, MJLJ will not be able to control rev limit since it is not powering the coils.

The way to do the install with rev limiter would be to get the tacho in between MJLJ & coil pack. In another words, it means I should disconnect the wire going from the ign. fuse box to the tacho and replace it with a wire going from the MJLJ to the tacho. 

[Leon]

Looking good Matt! If you're utilizing a hard rev-limiter, there are extra steps as you've noted. The Megajolt website has good info on that as well.

[winstonusmc]

How much to make me one of those handy sensor mounts? I want to get rid of my distributor all together.

[winstonusmc]

Deleted

 

Edited December 31, 2012 by winstonusmc

[Lazeum]

The sensor mount cost me 100€ but it was done by a supplier of my company as a personal "side project".

 

Hard rev limiter is using the MJLJ coil power to stop ignition, since I don't use this feature, I'm going to be able to have a hard rev limiter. I need to spend some time with wiring diagram. It is most likely a cable to unplug next to the fuse box & to connect to this unplugged cable power wire fromt he MJLJ.

[Lazeum]

Car started for the first time with no distributor this past weekend!

 

I've faced some issues that were easy too fix since they have been fixed by other members :

 

- No sparks - VR sensor wires were not plugged the proper way. I have attached blue on gray & gray on blue. Since sensor & EDIS controller were coming from the same donor, the right way was blue on blue, gray on gray. I knew immediately what went wrong as soon as I've noticed no spark, it was easy to fix thanks to info found on the forum.

 

- Backfires thru carbs without starting - I knew timing was off. I got confused with EDIS firing order A-C-B. Since nothing was written on the coils, I've also mixed up A with C & C with B, etc... it was a mess. For the record, here the correct diagram that works:

 

Once those 2 items were sorted, the car started right up! it still pops from time to time but I've only run it for 20 seconds max. I was in the garage (closed), roads are covered with salt. Tuning will be for spring.

 

Picture of the VR sensor & its support, I could have done it 1 or 2 mm taller (0.040 -0.080") , it would have put the sensor right in the center of the wheel. It is still in front of it though so I'm not concerned.

 

VR sensor is using one M6 bolt & one M5 bolt (for slotted hole), it did not notice it during part design. I've attached the drawings for your information (they are messy but every details are inside).

I've also forgotten in the drawing on the tower the counterbore for VR sensor recess (Ø9mm bore, 5mm deep)

 

Edited May 15, 2013 by Lazeum

[Leon]

Nice job! I faced both of those issues during my MJ install as well, it's a common theme. Can't wait to see it running and on the road! 

[Lazeum]

Me too!

My biggest unknown will be carb behavior with correct/optimal timing under low loads. I'm wondering if I won't have to lean out a little my transition circuit.

Now I need to fix my gas tank (full of junk - paint flakes from an attempt to coat the inside), I expect to open it up, sandblast it, TIG weld it, polyester resin coating inside & paint.

I've also a short somewhere blowing my head light fuses to find.... It never stops! :'(

[Git-y-up]

Amazing thread Lazeum. Yourself and Leon have convinced me entirely to go with this mejajolt setup. Simple and straight forward with great results.

 

Thanks for the effort,

 

Andrew

[Leon]

Amazing thread Lazeum. Yourself and Leon have convinced me entirely to go with this mejajolt setup. Simple and straight forward with great results.

 

Thanks for the effort,

 

Andrew

 

You won't be disappointed!