MJLJ/E communication failure.

bobclevenger · Post by **bobclevenger** » Wed May 11, 2011 10:15 pm

OK, here are some bracket photos.

This is the raw bracket as I received it from the shop that made it. Material is 1/4" mild steel.

This is the bracket and toothed vibration damper after painting. The notch in the bottom of the bracket is a mistake, but doesn't affect strength or function at all. The mounting screws for the sensor fit snugly and the sensor has no room for movement. Likewise for the bracket bolts. The vibration damper is a new unit that I had a shop here in Reno (Sparks, actually) cut the 36 teeth into the rim. After determining which tooth to remove, I ground it off with a bench grinder. I also corrected for the missing tooth's weight to retain proper balance.

This is a mock-up of the installation on a different 440 engine block. Note that the vibration damper has not yet had the "missing" tooth removed. This is how it sits on my engine, but with a slightly smaller gap between the VR sensor and the toothed damper. The yellow mark indicates the TDC position and the red mark indicates the VR sensor position (the marks are not actually on the parts). I then counted off 5 teeth from the VR sensor position and removed that tooth. I actually counted the wrong direction, so I removed the wrong tooth , giving me a 100° error. I corrected for this by shifting all the spark plug wires 90° (why limp mode was at zero° BTDC) and then shifting the VR sensor mounting position by one tooth to get the proper 10° BTDC limp mode (and a narrower gap). Obviously, to do this right using this VR mounting position, the tooth with the yellow mark should have been removed.

Regarding grounding (or 'earthing' as our British cousins say) I have both the ground pin of the MJLJ/E and pin 10 of the EDIS-8 grounded to the point on the vehicle body/frame where the battery's negative pole connects.

The shield drains of the shielded cables (one to the MJLJ/E carrying PIP and SAW signals), the other to the VR sensor) are connected together at the EDIS-8 ends and then connected to pin 7 of the EDIS-8 and then to the wire coming from pin 10 of the EDIS-8 (within 2"). The shield ends at the VR Sensor and MJLJ/E ends are not connected in an attempt to prevent ground loops. Do I need to run a separate ground wire from pin 7 to the battery negative point?

Just out of curiosity, was I supposed to get a mating Molex connector with the MJLJ/E? I just bought a matching connector at my local electronic parts shop, so I don't need one, I just thought it was odd that one wasn't included.

luxseven · Post by **luxseven** » Thu May 12, 2011 7:29 am

Nice work!
As for the Molex conn I bought my stuff at trigger-wheels.com and it was included.
Cheers.
Jos

bobclevenger · Post by **bobclevenger** » Thu May 12, 2011 10:29 am

Thanks. Now if I can just get this thing working right...

Post by **brentp** » Fri May 13, 2011 5:34 am

I'm highly curious as to the rough running / bucking symptoms you are observing when running on EDIS alone. Something is definitely wrong here, and should be resolved before dealing with the megajolt. Again, it should run *smoothly*, but with reduced power as it'll be fixed at 10 degrees BTDC.

If I were diagnosing it I would focus on:

* Stability / noise on power supply when engine is running. I would put a scope on the 12V power supply with the engine running to see what it looks like. if it's noisy, would suggest disconnecting alternator and running on battery power alone, in case this was a source of noise.

* Check all wiring, check +12v at the EDIS module power and the +12v power to the coil packs to see if there's any voltage sag.

* Check plug and plug wires for proper firing sequence. this is a longer shot as it should be obvious if the engine isn't running liquid smooth at idle.

* Monitor the VR sensor signal with a scope while running the engine through the RPM range.

Any other ideas out there?

Thank you for perservering, the solution will reveal itself!!

bobclevenger · Post by **bobclevenger** » Fri May 13, 2011 8:30 am

We seem to be thinking alike. Alas I have no 'scope. I have been thinking of running a bypass wire directly from the battery to the EDIS/coil pack power junction to see if the bucking may be caused by momentary power dropouts (possibly due to a faulty ignition switch). I have noticed that the bucking seems to occur only after the engine has been running for a while (enough to get fully warmed up). BTW, the coil packs are not yet firmly mounted, but stay put rather well... hmmm.... I wonder if grounding the coil pack cores via the mounting screws serves as a sort of shielding? Something to look into. I have been procrastinating building a bracket to hold the coil packs. Plug wires are a real longshot as the engine runs well most of the time. OH, how I hate intermittent problems! The real monkey wrench in this whole situation is that while the bucking does occur (intermittently, and only after a full warm-up) both with and without the MJLJ/E, it is less strong with the MJLJ/E connected than when running the EDIS alone. I would think that with the EDIS alone things would be more stable, not less. When running EDIS alone, the timing seems to be rock-steady at idle and when revving the engine according to my timing light. Unfortunately, I can't watch the timing light whilst driving, nor use the configurator software to observe operating conditions at this point.

With a moderately warm cam (Iskenderian 270 Mega-Hydraulic) I don't expect a silky smooth idle, but coughing under power is another matter entirely. The idle quality is actually somewhat better than it was with the stock distributor and MSD Street-Fire ignition.

I do need to get this sorted before too long as I must get a smog check before renewing my registration next month.

As another matter, why do you recommend that the vacuum line be connected to a port that always has manifold vacuum on it as opposed to a timed vacuum port such as is normally used for a vacuum advance system? It seems that the only difference is that when the throttles are fully-closed you would have less spark advance, but that under those conditions it wouldn't really matter all that much. Just curious.

bobclevenger · Post by **bobclevenger** » Sat May 14, 2011 3:31 am

Well, I have good news and bad news...

The good news is that I drove the car today in EDIS-only mode and it ran fine with no coughing and bucking. Plugged in the MJLJ/E and it ran even better. So that nasty intermittent bug seems to be gone.

The bad news is that I have no bloody idea what I did to fix it!
Prior to trying a direct ignition power lead from the battery (something I didn't want to do, because then there would be no way to stop the engine from inside the car!) I did some wiring changes and mounted the coil packs to their mounting plate (still not bolted down), but neither of these things should have made any difference. The wiring change was to reconnect the coil packs so that coil "A" is connected to pin 12 on the EDIS 8, coil "B" is connected to pin 8, coil "C" is connected to pin 9, and coil "D" is connected to pin 11. This allows me to use the "normal" plug wire connections with my missing tooth being 90° off from where it ought to be. Then I mounted the coil packs to the mounting plate, reconnected the plug wires, and set the coil pack assembly in place, and fired her up. She runs well. Getting the coil pack mounting plate bolted down will take some careful measuring and fabrication of mounting flanges (off to the fab shop I shall go).

I am about to take the laptop out to the car and see how things work...

OK, just got back from trying it. Everything works well!
Now I can get to work on creating a realistic ignition map for it.

Post by **brentp** » Sat May 14, 2011 5:09 am

Great news! ...In a way

Watch out for bad connections, because that intermittent problem could come back.

So, how does it run compared to the old distributor setup? Can we see some expanded pics of the car and installation? ("Powered By" Gallery)

bobclevenger · Post by **bobclevenger** » Sat May 14, 2011 7:17 am

Yeah, all I can figure is that one of the connections I redid wasn't good.

Seems to run pretty well, still adjusting the ignition map, and I'm sure that will take some time to get just right.

After I get the coil pack bracket mounted I'll take some photos and post to the "Powered By" gallery for sure. I'll be sure to warn people away from making my mistakes (counting 5 teeth the WRONG way!). I also plan to have a custom plug for the distributor hole made, but that will be a while down the road.

Thanks for all the help.

Post by **brentp** » Sat May 14, 2011 3:38 pm

Great! Glad things are figured out. I was thinking about this last night and realized there must've been a bad connection made worse with engine vibration- cutting power to the Megajolt and likely the EDIS module.

Can't wait to see the rest of the pics!