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  #1  
Old 06-17-2006, 02:07 PM
dgc333 dgc333 is offline
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Default MSD won't trigger off Mopar electronic distributor!!!!

I picked up an MSD 6A and went to install it today and it wouldn't start. Followed MSD'd trouble shooting guide and the MSD is producing a spark when either the white wire is grounded or the purple & green wires are jumped.

This tells me that the green / purple wiring is not getting a signal from the magnetic pick-up in the distributor. Double and Triple checked my wiring and connections with no luck. I can re-hook up the ECU and the engine runs fine.

What I did do was leave the MSD hooked up like it was a points ignition and used the (-) coil wire from the ECU to trigger the white wire on the MSD. Runs great.

My questions is shouldn't I be able to eliminate the ECU and trigger the MSD right directly from the distributor?

Any insites are welcome.
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Old 06-17-2006, 09:20 PM
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pishta pishta is offline
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You can use the Mopar ECU to fire the MSD all day long, you are only losing the internal amp of the MSD to trigger itself. You can even use the Mopar ECU to fire a coil from a point style ignition, youll never need to replace the points as the ECU is taking all the voltage, very little going to the points itself.
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Old 06-17-2006, 09:37 PM
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dave571 dave571 is offline
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You can eliminate the mopar ecu.

A mopar distributor CAN fire an msd. I ve done it many times, as have others.

Have you tried reversing the green and purple signal wires?

Check the air cap on the dist pu as well.
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Old 06-17-2006, 09:49 PM
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Quote:
Originally Posted by dave571
You can eliminate the mopar ecu.

A mopar distributor CAN fire an msd. I ve done it many times, as have others.

Have you tried reversing the green and purple signal wires?

Check the air cap on the dist pu as well.
You can if the MSD is working properly, his doesnt sound like his is. If the Purple/brown are reversed, itll still fire but itll be about 8 degrees off. Sounds like he is using the Mopar ECU because the MSD is crippled, and its working for him. Would the reluctor air gap setting fire the ECU but not the MSD?
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Old 06-17-2006, 10:48 PM
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moraycen moraycen is offline
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Red face yes it will

work . I have a 6al hooked to a stock mopar dist. in the race car. I cant tell you how its wired right now because its outside & im not. however I will look tomorrow and let you know.
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Old 06-17-2006, 11:30 PM
72Challenger 72Challenger is offline
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Just to ask a silly question, when you first hooked this up, you did connect the orange/white striped wire from the distributor to the purple MSD wire, and the black wire from the distributor to the green wire from the MSD?
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Old 06-17-2006, 11:33 PM
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dwc43 dwc43 is offline
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Biggrin

The MSD box will fire off of a stock dist. WE run MSD 7AL2's in our race cars with high vibe coils and modified Mopar dist. and they work fine. Do like Dave said and check the air gap and wiring. You may have a bad pic up as well.
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  #8  
Old 06-18-2006, 12:58 AM
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Quote:
Originally Posted by pishta
Sounds like he is using the Mopar ECU because the MSD is crippled, and its working for him. Would the reluctor air gap setting fire the ECU but not the MSD?

I doubt the gap will make a difference, BUT the msd usually works with a mopar dist. Perhaps the the msd is more sensitve to the ampliture of the pulse, than a stock ecu is. Maybe the gap is out just enough one ecu notices it, while the other doesn't.

Just an idea for a guy whose car is doing things that don't make a lot of sense.
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Old 06-18-2006, 08:34 AM
dgc333 dgc333 is offline
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I checked the air-gap it's at .008". The orange wire from the distributor is connected to the purple and the black is connected to the green. I also reversed them. Neither worked. Per the MSD trouble shooting guide jumpering those wires should create a spark and it does so the MSD seems to be working via that circuit.

I suppose it could be the pick-up but before replacing that I will wait to here from MSD's tech support before changing any parts. In the mean time it works when triggered by the ECU and it made a noticable improvement in the idle quality.

Thanks for the the responses.
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  #10  
Old 06-18-2006, 05:29 PM
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Glen440 Glen440 is offline
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The msd does not like a big reluctor gap. Tighten it up. I run it as tight as I can.
I switched to a msd distributer for this year. I used 3 different mp ones for the last 8 years. 2 were stock 1 is the adjustable unit. All worked fine.
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  #11  
Old 06-19-2006, 06:49 AM
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Just for trouble shooting... try jumping the car while using the MSD unit... I have found that if the cranking circuit uses to many amps, the MSDs don't get enough to fire... boosting the battery works every time... I have had this happen with MSD and Holley equipment. Even with full charged batteries and it sounds like it cranks great.

If it works at least you will know the problem and be able to work on that... If it doesn't, youÂ’re not out anything....
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  #12  
Old 06-20-2006, 10:42 AM
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pishta pishta is offline
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I was going to suggest that you check the small red "energize" wire to MSD to see if it is getting enough juice to turn the unit on. ie. you cant just use the coil wire after a ballast resistor at 6~9 volts to turn the MSD on when in "ignition". I dont know if you have it wired that way or not considering it is working somewhat as wired
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Old 06-20-2006, 11:01 AM
dgc333 dgc333 is offline
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The small red wire is getting power directly from a switched 12v source, the ballast resistor is not part of any circuit associated with the MSD, it's disconnected.

I did talk to MSD yesterday and they confirmed with confidence that if I get a spark by shorting the green and violet wires together that the circuit is working properly. That leaves the pick-up in the diostributor as the most likely culprit. I have not tried reducing the gap between the reluctor and pick-up to below 0.008" yet but will and will also try a new pick-up if that does not work.
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  #14  
Old 06-20-2006, 11:06 AM
dgc333 dgc333 is offline
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Quote:
Originally Posted by bigiron
Just for trouble shooting... try jumping the car while using the MSD unit... I have found that if the cranking circuit uses to many amps, the MSDs don't get enough to fire... boosting the battery works every time... I have had this happen with MSD and Holley equipment. Even with full charged batteries and it sounds like it cranks great.

The MSD works fine when triggered by the ecu using the white wire so I don't think it's the battery but I will check and see what my cranking battery voltage drops to the next time I play with it. MSD's spec states the unit works on a supply voltage of 10-18 volts.
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  #15  
Old 06-20-2006, 02:00 PM
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Quote:
Originally Posted by dgc333
The MSD works fine when triggered by the ecu using the white wire so I don't think it's the battery but I will check and see what my cranking battery voltage drops to the next time I play with it. MSD's spec states the unit works on a supply voltage of 10-18 volts.

I realize the spec of the device is 10-18 volts and it triggers off of the ECU... I have seen the same thing in the past... I also seen where two batteries are needed to trigger a device when no other reason is found...

I just thought it would be a very easy test to try to isolate a problem... here's one... I had an MSD pro billit dist... and a 6al box... everything worked but I had the timing locked and it was a little hard on the starter.... so I got a timing retard box(MSD) and installed it as per the directions.... It wouldn't start for anything... had lots of spark (or so it seemed) Threw the booster on it bang... took right off... figured it must have been the retard box and removed it... danged if I can tell you why, but it still wouldn't start by itself after that... replaced the 6al with a new box still wouldn't start(except with a boost)... hooked everything back up, replaced the battery with higher amp and fixed the problem.... put the old battery(not a small battery by any means) in one of the Fords and it's still there working just fine on the stock electronic ignition....

I have about 10 other strange but true tales of these after market ignitions...
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  #16  
Old 06-24-2006, 04:05 AM
djswwg djswwg is offline
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Very interesting and familiar comments on this topic. I'll add one more. The only trouble I find when adding an ignition box to an existing (and working well) Mopar system is that they become more sensitive to available voltage during cranking, and more sensitive to reluctor/pickup gap. Both of these issues have been dealt with by various members on this thread.
My first time problem was too big a gap (.013"). The car ran fine without the MSD but wouldn't work at all till we tightened the gap to .008", where it should have been in the first place!..............djs
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  #17  
Old 06-24-2006, 09:29 AM
dgc333 dgc333 is offline
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Well I haven't touched the ignition since last Saturday. I did drive the car to work 4 days this week (50 mile round trip) with the MSD being triggered by the mopar ecu. Car does run better.

I ordered a new pick-up for the exisiting distributor and also contacted FBO about building me a distributor with the correct curve.

I will up date the list when I have it all sorted out.
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  #18  
Old 06-24-2006, 11:55 PM
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pishta pishta is offline
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only thing you are hurting with the Mopar ECU firing your MSD is your timing as the ECU tends to alter your timing at higher RPM\s
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  #19  
Old 06-26-2006, 07:31 PM
dgc333 dgc333 is offline
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Well I figured out why my MSD would not trigger off the distributor and I feel foolish that I didn't check that in the beginning.

I purchased a two pin trailer connector at the parts store so I could splice it onto to the MSD harness so I wouldn't have to disturb the wiring on the distributor. Well the trailer connector did not fully seat into the connector on the distributor and wasn't making contact.

Once I replaced the connector with the end I had from an old distributor it fired right up.
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