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LDB4

Mopar ignition

I'm building a 1946 Dodge Pickup street rod. 340 CID with 727 trans,all old school with new components and electrics. Presently I'm running (trying to run) an aftermarket Mopar electronic ignition kit (orange box) with an Accell 140001 coil and 150001 resister. The system fired on the first crank ran and well for about 10 - 15 minutes then quit. The same system was in place when the engine was rebuilt and on the Dyno pushing 412 horse and 417 pound torque. it was run there for several hours for a good break in with minimal valve spring pressure, once everything was worn in the correct springs were installed and the Dyno tests run.

The engine will start and run when the starter is cranking (ing. #2 starter engage) but dies the minute I release the starter button. Replaced the resister and coil. I measured 11.45 volts at the hot side (Ing. #1 key on) of the resister, 1.85 coming out the outlet side (to coil positive & start side) and 1.2 to 1.8 Ohms resistance. Verified all the wiring has good connections grounds etc I am pulling my hair out any ideas out there? Frustrated LDB4

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Had the same issue years ago.  Turned out to be the ignition box. Changed to a chrome box and never looked back. Not a cheapy box from Orielly or Autozone a real Mopar Performance Chrome box.

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Well "Surfer 1420" I now own a new chrome ECU box and apparently an old but functional "Orange" ECU the new chrome box does exactly what the old one did, starts the engine fine but the engine dies the moment the starter is released! If I keep the starter engaged it will run fine. Please anyone else out there with "Ideas"? I can't afford to keep swapping out parts or I'll have to start a parts shop! New coil, new resister new ECU but will not stay running. Where I'm at a loss is that it ran on the dyno for hours with the same components and ran for fine for 10 to 15 minutes after the initial in vehicle first start up, now dies immediately after starter release

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On 7/11/2017 at 9:35 AM, LDB4 said:

I'm building a 1946 Dodge Pickup street rod. 340 CID with 727 trans,all old school with new components and electrics. Presently I'm running (trying to run) an aftermarket Mopar electronic ignition kit (orange box) with an Accell 140001 coil and 150001 resister. The system fired on the first crank ran and well for about 10 - 15 minutes then quit. The same system was in place when the engine was rebuilt and on the Dyno pushing 412 horse and 417 pound torque. it was run there for several hours for a good break in with minimal valve spring pressure, once everything was worn in the correct springs were installed and the Dyno tests run.

The engine will start and run when the starter is cranking (ing. #2 starter engage) but dies the minute I release the starter button. Replaced the resister and coil. I measured 11.45 volts at the hot side (Ing. #1 key on) of the resister, 1.85 coming out the outlet side (to coil positive & start side) and 1.2 to 1.8 Ohms resistance. Verified all the wiring has good connections grounds etc I am pulling my hair out any ideas out there? Frustrated LDB4

11.45V at the hot side of the resistor?  That sounds low to me with the key "on".  What was the battery voltage (across the terminals)?  Also that specific resistor is supposed to be around 0.85 ohms, and the coil around 0.7 ohms.  Disconnect both and check the resistance across there terminals, probably need a digital multi-meter for that.  Given that the resistor is inline with the coil, measuring the voltage from the outlet of the resistor (relative to ground) should be on the order of 11.45 * 0.7 / (0.7 + 0.85) = 5.1V, assuming the "on" resistance in the transistor in the ignition box is much less than 1.55 ohms (if it isn't the 5.1V number will be lower, but not 1.85V).  Doing some math to get some ball park numbers... with 11.45 V and 1.55 ohms of resistance, the peak current (when the coil is "saturated") the wires are conducting is roughly 7.3 amps.  That's a rather large current, the wiring and any switches in series with it have to be able to support that kind of current loading.

How is the ignition circuit wired up?

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The 11.45 is at the input side of the resister the voltage at the battery was 12.55. The 1.85 coming out of the resister is,I believe, the issue, but it is the third new resister each reading the same or very close. The ignition wiring is straight out of the Mopar manual for Electronic ignition. Hot is key on to the resister and ECU (Lt Blue wire) or Ing. #1 and the start circuit (A push button in line with a relay and the NSP engages the circuit) for Ing. #2 directly to the coil Pos. side and ballast out. Coil Neg. side is from the ECU (Blue wire /yellow tracer). I tried to load a scanned Circuit drawing but the file was too large.

Fresh readings are; Ballast 1.7 Ohms resistance when not connected, 11.42 volts in and 1.8 volts out, Coil shows .8 Ohms resistance and the battery readings are 12.52 volts at the posts.

I was tempted to just eliminate the Ballast resister running the Positive straight to the coil and ECU but was afraid I'd fry the ECU or the Dist reluctor. I was told by the ACCell coil folks that the #140001 coil is universal and doe not require a resister yet when I bought the new coil it came with a new Resister #150004 so I'm really confused on what direction to go next I've checkd and rechecked the wiring and it's all exactly as the book shows. The elephant in the room is why/how in the hell did it run fine on the dyno for hours, wired exactly the same way using the same parts and 10 to 15 minutes in vehicle after the initial start? I changed nothing when it died other than, assuming it was the resister, I bought an new one installed it and still no continuous run! If you would like to contact me on my E-mail <larrydeanback@gmail.com> I could send you the drawing we could go from there. Thanks for the response and input, LDB4

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6 hours ago, LDB4 said:

The 11.45 is at the input side of the resister the voltage at the battery was 12.55. The 1.85 coming out of the resister is,I believe, the issue, but it is the third new resister each reading the same or very close. The ignition wiring is straight out of the Mopar manual for Electronic ignition. Hot is key on to the resister and ECU (Lt Blue wire) or Ing. #1 and the start circuit (A push button in line with a relay and the NSP engages the circuit) for Ing. #2 directly to the coil Pos. side and ballast out. Coil Neg. side is from the ECU (Blue wire /yellow tracer). I tried to load a scanned Circuit drawing but the file was too large.

Fresh readings are; Ballast 1.7 Ohms resistance when not connected, 11.42 volts in and 1.8 volts out, Coil shows .8 Ohms resistance and the battery readings are 12.52 volts at the posts.

I was tempted to just eliminate the Ballast resister running the Positive straight to the coil and ECU but was afraid I'd fry the ECU or the Dist reluctor. I was told by the ACCell coil folks that the #140001 coil is universal and doe not require a resister yet when I bought the new coil it came with a new Resister #150004 so I'm really confused on what direction to go next I've checkd and rechecked the wiring and it's all exactly as the book shows. The elephant in the room is why/how in the hell did it run fine on the dyno for hours, wired exactly the same way using the same parts and 10 to 15 minutes in vehicle after the initial start? I changed nothing when it died other than, assuming it was the resister, I bought an new one installed it and still no continuous run! If you would like to contact me on my E-mail <larrydeanback@gmail.com> I could send you the drawing we could go from there. Thanks for the response and input, LDB4

 

I actually have an old set of instructions for the MP electronic ignition conversion kit I bought way back in the late 90's for my truck, so I have a pretty good idea what the wiring schematic probably looks like.

Disconnect the lead going to the coil at the coil, leave the other side connected to the resistor and turn the ignition switch to "run".  It should read the same voltage as the hot side of the resistor.  If it's lower there's something conducting current when its not supposed to be on the "start" side and stealing current away from the coil.  You could check that the resistor doesn't have a short to ground (both sides disconnected) as well (seems unlikely).

Given that the engines runs as long as it is in "start" leads me to believe the wiring from the coil to the ignition box, and the grounding of the box may be OK.

The reluctor pickup wont be harmed, as it doesn't carry any of the ignition coil current, it just sends out small pulses of voltage/current each time one of the reluctor "points" passes over it.  That signal feeds into the ignition box as a trigger to turn the big transistor mounted on the outside of the box off and on.  How much current that box/transistor can handle... is a good question.

Losing 1.1 volts through the wiring/switches is not good, that's roughly 8 watts of power being dissipated over I would guess is a fairly short run of wiring, or in a switch, or connection(s), and likely to get worse over time.  I'd try to get it to 0.5V loss or so.

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I went through this exact problem on my Dart. 1970 340 Dart running an MSD 6AL. Motor would fire but die as soon as stopped cranking. There is one difference with mine not using the ballast resistor. But it's the same issue. Give me a PM I may be able to help.

Sent from my SM-N920V using Tapatalk

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Sorry, 586-909-3689 is the Phone number, part number for the coil is 140001 resister 15004 (I think) am sure of the coil number. LDB4

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