EFI- old MoPar- where to get "true power"? Start/run
#2592560
12/15/18 10:50 PM
12/15/18 10:50 PM
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Joined: Oct 2004
Posts: 16,480 Canada
CrAzYMoPaRGuY
OP
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OP
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We are converting a 1969 B body to EFI. Instructions say ECU needs a wire to go to start AND crank 12volt power. Power cannot drop below 9 volts. We tried the ballast, it's a 4 pin ballast, but nowhere do we get sustained 9+ volts during start AND run.
I thought relay maybe? Would 6 volt at ballast pull in a relay?
What has been done for a 1969 B body to get voltage for start and run power at the ECU that works??
CrAzYMoPaRGuY
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592563
12/15/18 10:55 PM
12/15/18 10:55 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
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up yours
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There is no ONE source for that. In start the ignition switch feeds the coil 12v bypassing the ballast, in run the ignition switch shuts that feed off and feeds the coil through the ballast. You need to tie both of those feeds together to get the 12v power your EFI is looking for. Are you using the EFI for ignition as well? If so you can just tie those two feeds together. If you plan to use a separate ignition you will need to use a diode to isolate the feeds from each other while they still feed the EFI.
I'd use those feeds to run a relay and use the relay to feed the EFI direct from the battery.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592578
12/15/18 11:47 PM
12/15/18 11:47 PM
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Joined: Jan 2003
Posts: 31,074 Oregon
AndyF
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I Win
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Posts: 31,074
Oregon
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On my '65 B body I tie start and run together and use the combined switched 12 volt to power the EFI and the ignition system. I also use it to power up the alternator although the alternator really only needs the run line. However, once you tie them together they are together unless you get fancy. My car has been "modernized" so I ditched all of the old Mopar wiring. No more ballast resistor, no more start and run circuits, no more passing all current thru the firewall to the ammeter, etc. Trashed all of that old school Mopar engineering.....
Last edited by AndyF; 12/15/18 11:47 PM.
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592581
12/15/18 11:52 PM
12/15/18 11:52 PM
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Joined: Nov 2006
Posts: 2,260 IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,260
IL
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I did similar to Andy. If you're using modern ignition you don't want the ballast in there anymore reducing the voltage anyway. Tie it together and bypass the ampmeter circuit while you're in there
70 Sport Fury 68 Charger 69 Coronet 72 RR
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592609
12/16/18 12:48 AM
12/16/18 12:48 AM
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Joined: Oct 2004
Posts: 16,480 Canada
CrAzYMoPaRGuY
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OP
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K so...... we tried many things. The instructions are from the Professional Products kit. It says to go to the power side of the (4 pin) ballast resistor. It also says voltage should not drop below 9 volts at any time.
Voltage drops below 9 volts if wired as it says.
We tried to run side of ballast and it doesn't start as easily as if we run the wire directly to the battery. We read the instructions again and it says to pull the power directly off the + side of the coil. But not if a ballast resistor is used. This actually works the best by far.
We then thought maybe a relay pulled in by the coil voltage with 12 volts coming directly from the battery might even work better. We are just concerned about pulling a coil in from the positive + coil terminal.
Ma Mopar... what were you thinking? lol So.... he has an Ehrenberg box I believe the HiRev kit. Can we get rid of the 4 pin ballast somehow? Argh.
Kit runs pretty danged good, hasn't had time to learn much but it's got throttle response and once running it's no complaint here. We don't want to fry coils and relays and wires by doing things wrong. "True Power"? Engine maybe! We have ignition 1 and Ignition 2! We are trying to wrap our heads around the response so far! Thanks. Thanks for being patient!
CrAzYMoPaRGuY
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592617
12/16/18 01:00 AM
12/16/18 01:00 AM
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Joined: Oct 2004
Posts: 16,480 Canada
CrAzYMoPaRGuY
OP
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OP
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Posts: 16,480
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Here's our diagrams we used
CrAzYMoPaRGuY
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2592618
12/16/18 01:01 AM
12/16/18 01:01 AM
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Joined: Oct 2004
Posts: 16,480 Canada
CrAzYMoPaRGuY
OP
I Live Here
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OP
I Live Here
Joined: Oct 2004
Posts: 16,480
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We have the 4 pin ballast. We considered swapping to a 2 pin ballast. Whatever works! lol
CrAzYMoPaRGuY
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: BDW]
#2592890
12/16/18 06:50 PM
12/16/18 06:50 PM
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Joined: Oct 2004
Posts: 16,480 Canada
CrAzYMoPaRGuY
OP
I Live Here
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OP
I Live Here
Joined: Oct 2004
Posts: 16,480
Canada
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AWESOME. Diode hunting we go. Thanks everybody!!!!
CrAzYMoPaRGuY
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2593203
12/17/18 03:45 PM
12/17/18 03:45 PM
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Joined: Aug 2003
Posts: 43,292 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,292
Bend,OR USA
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You need to know that all diodes are a one way electrical devise use to stop the current from reversing, flowing backwards, one way I'm not sure if they are current limited or not Meaning maybe you can you blow them open with to much current They are used to rectify A.C. from alternating to direct current in alternators when used as a full wave circuit IHThs OP, does your EFI and ignition require a specific lower voltage to the ignition ECU? If not bypass the resitors
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2593640
12/18/18 09:17 AM
12/18/18 09:17 AM
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Joined: May 2005
Posts: 4,753 Florida
BDW
master
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master
Joined: May 2005
Posts: 4,753
Florida
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Correct, in the link above there's an EBay link for diodes used in solar panels. Plenty of current capability and only $1 each. Here it is again, I put 2 in parallel as a safeguard in case 1 of them fails. Plus it doubles the current available. https://www.ebay.com/itm/Pack-Of-10-Scho...a-/381734805254
Last edited by BDW; 12/18/18 09:23 AM.
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Re: EFI- old MoPar- where to get "true power"? Start/run
[Re: CrAzYMoPaRGuY]
#2593698
12/18/18 12:22 PM
12/18/18 12:22 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Or you could just use that signal to trigger a 30A relay fed directly from the battery and avoid all the old wiring issues.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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