Can a MJLJ 3 guru check my numbers?

EDIS and Megajolt installation related topics. Be sure to review the <a href="http://www.autosportlabs.net/MJLJ_V4_vehicle_installation_guide">Vehicle installation guide</a>

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paulc
Posts: 66
Joined: Thu May 01, 2008 10:49 pm

Can a MJLJ 3 guru check my numbers?

Post by paulc »

I was trying to get my car running this afternoon, to no avail, so i popped online to do some troubleshooting and found MartinM's thread (http://www.autosportlabs.org/viewtopic.php?t=734).

I don't seem to be getting any spark (even pulled a spark plug to manually check by grounding it to see for spark).

So - in the spirit of troubleshooting - Here is what i had for reading on my basic digital multimeter:

VR sensor - measured across EDIS pins 5 and 6 at the main connector with the connector disconnected from the EDIS ie this is the open circuit VR sensor voltage:
- 0 volts AC stationary - 0 Volts AC
- 2.3 volts AC cranking - 1.7 Volts AC - is this ok?

PIP pulse - measured at EDIS pin 1 with the main connector connected to EDIS:
- 12.3 volts DC stationary - 9.4 Volts DC - is this ok - seem low, but my whole MJLJ build showed #'s like this?
- 5.4 volts DC cranking - 4 to 7 (fluctuating) Volts DC - Good that it is 1/2 of stationary, right?

SAW pulse - measured at EDIS pin 3 with main connector connected to EDIS and MJLJ SAW output connected to EDIS:
- 0 volts AC stationary - 0 Volts AC
- 0 volts DC stationary - 0 Volts DC
- 0.14 volts AC cranking - 0.1 Volts AC - my multimeter doesn't go any more accurate on this reading
- 0.06 volts DC cranking - 0.01-0.04 Volts DC - is this ok?
MartinM wrote:I though it might be useful to measure and document the cranking voltages around my working system to potentially help others with installation problems.

I disconnected the plug from the coil to stop the engine (Peugeot 205GTi, 1580cc, OE fuel injection and MJLJ v3 with MAP sensor) and cranked the engine on the starter motor.

Battery voltage was about 12.3v and I used an auto-ranging digital multimeter on DC and AC voltages.

VR sensor - measured across EDIS pins 5 and 6 at the main connector with the connector disconnected from the EDIS ie this is the open circuit VR sensor voltage:
- 0 volts AC stationary
- 2.3 volts AC cranking
Explanation: VR sensor produces a +ve and -ve swinging AC voltage as a result of the ferrous teeth of the trigger wheel passing close to the magnet at the end of thw sensor. Wire wrapped around the magnet picks up the change in magnetic field and converts it to an AC voltage - just like a motor in reverse, really
Demonstrates: A working VR sensor

PIP pulse - measured at EDIS pin 1 with the main connector connected to EDIS:
- 12.3 volts DC stationary
- 5.4 volts DC cranking
Explanation: The PIP pulse produced by the EDIS is a 1:1 mark/space ratio 0v to 12v pulse train with a frequency proportional to engine rpm. When measured with a DC voltmeter, the voltage measures around half the supply voltage, which seems reasonable given the 1:1 mark/space ratio.
Demonstrates: A working VR sensor and a probably working EDIS module with regard to generating PIP pulses

SAW pulse - measured at EDIS pin 3 with main connector connected to EDIS and MJLJ SAW output connected to EDIS:
- 0 volts AC stationary
- 0 volts DC stationary
- 0.14 volts AC cranking
- 0.06 volts DC cranking
Explanation: The SAW pulse produced by the MJLJ is a 1:lots mark/space ratio pulse train with a mark/space ratio that increases as timing tends towards TDC and an overall frequency proportional to engine rpm. When measured with a voltmeter, the voltages are very low since the pulse train is at 0v for most of the time. I don't really know why the voltage appears higher on the AC range!
Demonstrates: A working VR sensor, a probably working EDIS module with regard to generating PIP pulses and a probably working MJLJ with regard to producing SAW pulses

It would be useful if someone else could do the same tests to verify these figures - post the results here please.


brentp
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Post by brentp »

A common cause for 'no spark' on new installations is reversed VR sensor connection. Try swapping the VR sensor wires and see if that fixes it.

Your voltages seem fine otherwise...
Brent Picasso
CEO and Founder, Autosport Labs
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paulc
Posts: 66
Joined: Thu May 01, 2008 10:49 pm

Post by paulc »

thanks Brent. I believe i had the coil pack plug wires all mixed up.

http://www.autosportlabs.org/viewtopic.php?t=1929

I built up oil pressure and found some big-old-leaks, so i gotta fix them first. I'll kep you guys posted. :?

brentp
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Post by brentp »

Typically with mixed up coils the engine should at least cough and backfire. i.e. it should produce sparks on cranking.

Good luck regardless!
Brent Picasso
CEO and Founder, Autosport Labs
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paulc
Posts: 66
Joined: Thu May 01, 2008 10:49 pm

Post by paulc »

oh ya - not only did i have the coils going to the wrong plugs, but the VR sensor polarity was wrong.

tried the VR sensor as a last resort (i actually had the old ignition system on the bench ready to go in)

swapped gray/blue wires on the VR and reconnected the ground shield wire.

i fired it up - heard / felt it stumble. fixed the coil pack/plugs and i it fired up instantly. it idles at 900 RPM and has crazy fast throttle response!

now i gotta figure out how to tune the thing. :oops:

oh - and many many thanks Brent. thanks for your eagle eye on my soldering, and suggestion for getting it up and going.

brentp
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Post by brentp »

Super!

Don't forget to add your car to the "Powered by" Section, with pictures! :)
Brent Picasso
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DannyP
Posts: 417
Joined: Sun Apr 09, 2006 3:48 pm

Post by DannyP »

Pretty much what happened to me, Paul. Turned it over, nothing. Reversed VR wires, instant start and idle!

I had the VR and coil wires in place but just twisted together, not soldered. I planned for this, hey, you have a 50-50 shot with each set of wires, right? Luckily my coil wires were correct and only the VR needed swapping. Over 2000 miles since the best thing to ever happen to my engine!

paulc
Posts: 66
Joined: Thu May 01, 2008 10:49 pm

Post by paulc »

if i recall, i wired it based on what i read here and other places online (VR polarity), but it's opposite.

I have kept an up to date wiring diagram, so i can tell you what wire goes to what position (when i get home)

DannyP
Posts: 417
Joined: Sun Apr 09, 2006 3:48 pm

Post by DannyP »

Some Ford sensors have the same colored wires, but reversed polarity. So whatever works, leave it that way!

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