slight ot - how would the megajolt work with the standard dme, for giving the dme timing signals for fuel?

 

Not really sure if it even talks to the DME, I believe it's standalone. The DME still gets RPM/TDC signals from the reference sensors in the bellhousing. Easiest thing to do would be to use a timing light to read the current ignition advances across the rev ranges and use that to make a simple map. Then tune it under load.

That's one of the reasons I decided MS was the way for me... one ($40) sensor on the crank pulley, one controller, no more playing games with the reference sensors.

 

i guess itd be doable to leave the speed/ref for fueling, then just add the MJ/EDIS with its own sensor up front if you just wanted a more accurate/powerful spark.

power the EDIS with the 944 coil black wire, but what do do with the green wire?

 

I would leave it floating (but covered at the terminal), it's just a ground.

You actually might know this better than me, but is there a relay on that black power wire to the coil? Or does it go right through the ignition switch? I see a couple relays under the dash but dunno. On my build, I sent the coils through a relay (on the fuse/relay board I made) just to be safe since they peak at 8A each. That's 16A peak since they're wasted spark, potentially a bit much for the early ignition switch.

Not sure how much current the stock coil draws compared to EDIS. I would multiply it by 2 just to be safe since the EDIS coil pack fires in wasted spark, where obviously the stock coil fires sequentially. Perfect chance to make a relay board and delete the DME relay

 

The wiring diagram doesn't show a relay, it comes straight out of the ignition switch.

 

The coils get 12v straight from the switch, no relay. Michael, you are correct that our LSx coils draw 8 amps peak, 16A peak draw directly through the ignition switch due to wasted spark firing in pairs. It is my understanding and personal experience that this is will within the current handling abilities of the switch. My coils are hardwired, all 4 share a common ground to the battery, a common "logic level return" to the MS, and a common 12v source using the same wire that originally supplied the stock coil.

 

Doug, I have more faith in the late ignition switch. The early switch is a POS and I've had to replace it twice already as it is...

My coils are wired slightly differently. Instead of using a signal return ground for the logic level signal, I just coupled that to the high power ground (to rear of intake manifold). No problems yet. I wanted to do a low power ground but the MS page on wiring LS coils seemed to always group the two grounds together. Like yours, they share the same 12v delivery.

 

i need to do my ign switch, at $5 ea i can live with it

although i did start considering just putting a push-to-start in the stock ign lock

 

You may or may not experience noise issues with rising RPM with the high power ground and logic grounds crossed. Michael, you already know this but to everyone else, Michael may get away with doing that but IN GENERAL: It is EXTREMELY important to keep high power grounds separate from low power common returns to the MS, they are distinctly different and the first and most important part of a successful EFI install is good grounding practices. Michael, let me know, I honestly have some concerns about the way your coils are going to act under high rpm, high load situations.

Also for the record I am running the filter capacitors and I did notice a difference after adding them.

 

Was going off this diagram:




I probably will go back and redo that grounding strategy, plus add the capacitors. People say they are optional but helpful. Have had zero issues so far (except for my bolt-dropping dumbassery) but why not make it bulletproof.

Spencer your job is to one-up our ignition...lol

 

He's going to have a tough time, LSx coils wired up in wasted spk are about as solid of an ignition system as you'll get on our cars. Only way to improve is to add a 4-1 cam wheel and go sequential spark, but the gain going from WS to sequential is way less dramatic than going from a single coil system to COP WS. Plus I've read some documentation that roughly stated the secondary low power discharge on the exhaust stroke is beneficial in obtaining a clean, complete burn and you lose that second discharge going to sequential spark.

Now, with our large bores what we really need (nobody shoot me for this, I'm sure most of us have has the displeasure of servicing a dual plug engine like a 993) is a twin plug setup :x I believe we would see measurable gains going to a twin plug head with a redesigned "penthouse" style chamber.

 

Many engines on VERY old cars had multiple plug setups.Some even had 3 plugs per cylinder.One for starting, and the other two for running. With a twin plug setup, some cars received a HP gain of up to 10-15 HP...This is also noticeable in aircraft engines with twin plugs..and they run HUGE bores! Although they primarily do it for redundancy instead of HP gain.

 

Full. Speed. Ahead. Michael! You have been doing a great job. Thanks again for documenting everything for the rest of us mere mortals.

 

I'll see what I can do...I've heard something blowing in the wind about an easy upgrade...I'll post it up when the time is right.

 

Dual spark would be interesting for sure...or a 20v configuration (3 intake, 2 exhaust). Audi got away with it right?

Thanks Noah, but seriously, this is something the average guy CAN do! It's a time investment at every level but has been worth it. It's like lending free time to your future self...because the next time something hits the fan, it will be a breeze to troubleshoot, repair, and cheaper to replace. Plus options for hardware and location.

Unfortunately MS doesn't help when you drop a bolt into the bellhousing and my car's been on jackstands for a couple days because of that. Bellhousing is off the car, so the bolt must be behind the flywheel. Bastard.

Here's a short video of the car starting and running from about a week ago, will get driving footage after it's all back together. It's smoother at every level and without a doubt pulls harder, especially when wound up a little.