General Topics for configuring, operating and tuning the Megajolt. Also see the <a href="http://www.autosportlabs.net/MJLJ_V4_Operation_Guide">Operation Guide</a>
Just had my car on the rolling road to get set up ready for the SVA. Once I got all the glitches sorted out we did the first power run where it became apparent that the ignition was too far retarded, the laptop showed the advance changing to reflect the area of the map that was highlighted at that point. However, the timing light showed a pretty static 11 degrees suggesting that the EDIS static advance was in operation. What on earth is going on??? Is the Jolt fried in some way, are there outputs to the EDIS that I can measure in some way to find out if the Megajolt is not actually replying to the EDIS despite the rpm signal getting to the Megajolt Not too happy at the moment as it was a little embarassing not to say an expensive waste of time.
The MJLJ cannot, of course, determine if the EDIS module receives the SAW pulse.
When was the last time (before the rolling road session) that you verified the ignition advance being affected by the MJLJ using your timing light? Did something change?
You can measure an AC voltage on the SAW output when operating. Also, check your wiring (if you are not already...)
Best of luck,
Brent Picasso
CEO and Founder, Autosport Labs Facebook | Twitter
You star yet again. Havent tried the timing light since the children are supposed to be in bed going to sleep, but you might well have hit the nail on the head. Since I last tested it I have taken the plug out to fit the tacho feed wire and this time when I ran the circuit tester over the plug the SAW terminal fell out the plug as I was trying it. DOH!! Will run the timimg light again on Saturday or tomorrow if I get in early enough.......
Well after the glimmer of light when the SAW terminal fell out, darkness has returned.
Tested the car with the timing light, (having had to buy a new one since I dropped the borrowed one and bust the bulb!). This time the timing mark does not move no matter what the revs, still static on 10 degrees. I have tested the pin 3 on the EDIS and there does seem to be a variable voltage (0.2-0.3) depending on rpm which I hope is what should be there. Has my EDIS died????
Just to confirm. If I stick the voltmeter into the back of pin 3 on the EDIS when it is running what sorts of voltages should I see between pin 3 and ground?
The steps you can do to verify this before you get your hands on the oscilloscope are (and I'm sure you've done most of these steps several times)
1. Make sure you have PIP and SAW connected correctly on both the MJLJ and EDIS side
2. Verify runtime activity on the software
3. Verify an AC voltage on the SAW pin
4. Swap out the EDIS module
You earlier mentioned that Pin 3 fell out of the EDIS module: this is concerning. Do you know for certain that it's making good contact when plugged in? the fact that your engine runs at all is a good sign, because it indicates at least partial operation of the EDIS module.
When you get access to an oscilloscope, preferrably a 2 channel scope, you can hook channel 1 to the PIP and channel 2 to the SAW. you should see the PIP signal with the SAW signal following immediately afterwards.
Also, make sure you have the PIP line correctly connected, because the MJLJ can be fooled into accepting a PIP signal from one of the other lines, like the IDM output.
Have swapped EDIS modules, checked wiring and used the oscilloscope to check PIP and SAW. The scope shows both PIP and SAW changing as they should, the only query is that the SAW voltage high level is only 2.6 volts which presumably isn't enough to trigger the EDIS? We have taken these readings from inside the EDIS so we know the connections are good.
2.6V is low. you should be seeing a 5V square wave on the SAW line following the PIP signal.
Measure the open circuit voltage by disconnecting the SAW line and running / cranking the engine. does the signal jump to 5V?
The SAW output circuit is simple: the processor feeds the SAW signal through a 100 ohm current limiting resistor, R1. Also try measuring the SAW voltage on either side of R1.
Brent Picasso
CEO and Founder, Autosport Labs Facebook | Twitter
Now the resistor has been replaced the car is fully working.
I have even managed to get my tacho to work, none of the usual solutions worked but now I have excluded the Zener diode from the coil flyback circuit the tacho takes signal from both coils, not sure how accurage an early 70's Smiths tacho actually is but it is at least as accurate now as at standard.
I look forward to getting the car back to the rolling road for a proper session.
just posted on your other post, ther is an adjustment variable resistor on the back of the smiths tacho so u can set it up for accuracy! not sure if this is limited to a specific band of rpm but if u set the smiths tacho to the same as the MJLJ tuning tacho at 3/4 full rpm im sure when its important everything shud be close enuf!
we did the first power run where it became apparent that the ignition was too far retarded, the laptop showed the advance changing to reflect the area of the map that was highlighted at that point. However, the timing light showed a pretty static 11 degrees suggesting that the EDIS static advance was in operation. What on earth is going on??? Is the Jolt fried in some way, are there outputs to the EDIS that I can measure in some way to find out if the Megajolt is not actually replying to the EDIS despite the rpm signal getting to the Megajolt 
Not too happy at the moment as it was a little embarassing not to say an expensive waste of time. 
