no spark from coil

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steveh

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electronic ignition wth stock coil and ecu. was runnin fine but now has no spark.

12v at battery 10.8v at ecu side of ballast...8.7 other side and 8.5v at coil. what should it read

new ballast and coil from othr daily driver...ecu is grounded

runnin out a daylight and don't want to leave iit in the parking overnight...need help troubleshooting
 
Run a wire direct from batter to coil + and see if you have spark

Loosen/ tighten mounting bolts at ECU several times

wiggle all connectors, the ECU, the ballast, and especially the distributor.

Check spark right at coil tower.

Try cranking with the key, and and also again with the key "in run" but jumpering the starter relay.
 
67Dart273 said:
Run a wire direct from batter to coil + and see if you have spark

Loosen/ tighten mounting bolts at ECU several times

wiggle all connectors, the ECU, the ballast, and especially the distributor.

Check spark right at coil tower.

Try cranking with the key, and and also again with the key "in run" but jumpering the starter relay.
Click to expand...


I'm by myself so jumped the relay for all of my volt measurements...spark check was from coil wire

jumper from batt + to coil+ will tell me what? not bein a smart @$$...just no internet where she broke down...thx steve
 
meant 2 say all spark checks were by jumping relay...volt readins were with key in run position...sorry 4 the confusion
 
Running a jumper from battery to coil + will eliminate key/ bulkhead/ harness wiring problems, is the equivalent of "hot wiring."

Using the key vs jumpering the relay causes different voltage to the ignition............Jumpering the relay still leaves the ballast in the circuit and causes low ignition voltage. If battery is low, etc, this might be enough to "not" get spark. Running a jumper wire will help that problem.

Without spare parts "on scene" this could be a problem.
 
67Dart273 said:
Running a jumper from battery to coil + will eliminate key/ bulkhead/ harness wiring problems, is the equivalent of "hot wiring."

Using the key vs jumpering the relay causes different voltage to the ignition............Jumpering the relay still leaves the ballast in the circuit and causes low ignition voltage. If battery is low, etc, this might be enough to "not" get spark. Running a jumper wire will help that problem.

Without spare parts "on scene" this could be a problem.
Click to expand...

oh its a problem alright...:violent1: had a spare coil and ballast but still no spark

ran to oreillys [hate that place] real quick picked up a$30 Chinese ecu...still nospark but it seemed to cure the votage drop at the coil...batt was down 2 12.4 but I was getting 12.1 at the coil

chargin batt at home now...praying they wont tow it...
what should I try first 2morrow
 
A big change in voltage with a change in ECU is a little troubling

This is because the Mopar ECU DRAWS COIL CURRENT with key on/ engine not running

Here's what this means

Your current path is battery....through harness.....ignition switch....through harness.....to ECU and ballast resistor......through the coil.......back to the ECU (coil NEG) and to ground.

In other words you have a current path through the coil and ECU

WHAT THIS SHOULD DO is cause you to read "close to battery" voltage at the "switch" end of the ballast but much LOWER voltage at coil positive after it has dropped through the ballast.

After the voltage has dropped through the coil, the ECU being the ground for the coil NEG.....the coil NEG terminal should read almost nothing.

You sure you grounded the new ECU?

Could be distributor pickup, etc, but that's hard to troubleshoot, other than checking reluctor gap, then just swapping either a different distributor or new pickup coil, and changing the pickup coil is no fun "on the side of the road."

If you can afford it, I'd buy a rebuilt distributor. Any electronic distributor from 72 later that has a vacuum advance for a small block

If you run a tach, disconnect it for now
 
had to replace the pickup coil 1yr ago been runnin fine 4 5000 miles

the neutral safety switch wiring cap wasn't getting a good conection a few day back...but its turning over now so that cant be it

I can pull the dizzy out of the cuda and try it...did not know that the reluctor could effect the circuit and prevent a spark from the coil tower...

any other ideas before I start canballizing one 2 save the other
 
Didn't know you had two. I'd pull the ECU, the distributor and ballast, and get / make a good long clip lead so you can hot wire if necessary. Where you're parked out in a vulnerable place that's the best way, "quick." Make damn sure the ECU is grounded. "Work" the connectors in/ out several times to scrub the terminals clean.w
 
im no mechanic so got the wife convinced I need 2 daily drivers so she doesn't have 2 share the minivan=P~

can you pls explain how the pick up coil works in the circuit

since I had no spark coming from the coil tower, I automatically assumed the problem must be somewhere from the coil wire back...didn't realize it might be in the dizzy...lots idont know so if you can clear it up 4 me id greatly appreciate it

thx
steve
 
The distributor contains the pickup coil which also has a magnet as part of it. The toothed reluctor wheel, when passing the pickup coil generates a small pulse of electricity. This feeds to the ECU via the 2 wire connector from the distributor and triggers the ECU to make a spark.

It is difficult to pin down trouble with this system for a certainty. The distributor generates a very very small signal, about 1 volt AC. Because of this any looseness or corrosion in the 2 wire distributor connector can cause corrosion.

The pickup can be gapped just like a set of points to a tooth on the reluctor. You are supposed to check this gap at .008" (inches not metric) and make sure when the vacuum advance moves, the reluctor does not strike the pickup coil. Incidently, inspect inside the cap for strike damage, rust, or debri sticking to the magnet around the pickup coil.

One thing I forgot. If you turn the key to 'run' and disconnect the distributor, and take the 2 wire connector in the harness---which leads to the ECU, and if you ground the proper one of those two wires, you should get one spark each time you do so. I don't remember which of the two wires---but just try them both. It will not hurt anything. No spark.......something in the harness or box. If you get a spark, likely the distributor is bad

Many of us here run Mopar breakerless distributors but with a GM HEI module instead of a Mopar module. I fixed up a box for testing engines, and to carry in the car for emergency ignition. That box plus a spare distributor should take care of any problems

This is the box, made out of "junk" parts, an old but good coil, a project box, and an HEI module. You hook up the high voltage coil wire, the two wire distributor connector, ground the green, and hook yellow to battery and you have ignition

hwlcfa.jpg


This is the diagram of the HEI, I run this on the car as well as the emergency box. No ballast resistor needed, and while some guys run hotter coils, I just run the stock coil. That is, below is "what's in" the box

There's a small plastic locater pin on the bottom of the module. You must break that off, and mount the module to flat metal for a heat sink. I simply have mine screwed to the firewall. You ground it through the mounting screws and hook it up

zu5qn8.jpg
 
Just for the satisfaction of it, try crimping the connector for the distributor a little.
I have seen a few of them loose contact, so I remove that plug and soldered the wires.
 

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ok now I'm at a complete loss. installed coil, dizzy, ballast and ecu from a running car...grounded ecu to batt...and still no spark

jumper from starter relay to coil + and nada.

12.2v at coil + and -...shouldn't there be a large drop??

gotta get it fixed or its gonna get towed
 
Could it be in the ign switch?? Neutral safety switch?? Sorry Im at a loss too and throwing **** at it....Maybe send 67dart273/Del a pm. He knows his stuff.
 
4spdragtop said:
Could it be in the ign switch?? Neutral safety switch?? Sorry Im at a loss too and throwing **** at it....Maybe send 67dart273/Del a pm. He knows his stuff.
Click to expand...

yeah he knows elec...was helpin me yesterday...hopin he will be on line soon
 
Is your rotor turning for sure when ya crank it over?? Maybe something is f'd with the dizzy gear down below??
 
I certainly would check for rotor movement. Any reason to think the chain / sprockets are worn? Did it run wierd or make noise when it quit? When cranking does it sound normal, as normal compression?


1.....Is the ballast on the dead car 4 or 2 terminal, and is the ballast on the running doner 4 or 2 terminal? This is because older ECU's known as "5 pin" MUST have a 4 terminal ballast. You cannot tell by looking at the box. Many aftermarket, newer, "4 pin" boxes still had 5 physical pins. It's just that one was dead.

So a 5 pin box MUST have a 4 pin ballast, but a newer "4 pin" box can use either 4 or 2 terminal

2...Might be the coil wire, check for spark right at the coil by using something like a grounded screwdriver or clip lead

3...Disconnect everything from coil except two ignition wires. If there's a tach, disconnect. If there's a radio condenser on the positive wire, disconnect.

4....Double, triple check ECU for GROUND. It MUST be grounded. Once again, with key "in run" the coil will be drawing current sitting at rest. This means you should see the following voltages

On "key" side of ballast, "same as battery" or very near, IE 12.6 or so

On "coil" (this is same as coil +) side of ballast a quite low voltage. This will vary, and might be all the way from 4--8 volts

(Obviously if you hot wired battery to coil + it will be at battery voltage

On coil NEG terminal you should see a very LOW voltage, probably below 1 volt. This is because the coil is (or should be) going to ground back through the ECU. This should hold true whether the ballast is in the circuit or not

5...Try the trick of leaving the key on, and grounding first one, then the other, of the distributor harness connector terminals. One of those terminals should produce a spark, each time grounded. If so, the ECU and wiring is probably good

6....Wiggle your wire connections, especially the ECU connector, and inspect internally

7....Since you are "out" you might want to do a half assed hot wire/ rewire to see if the harness is bad YOU CAN ACTUALLY DO THIS with clip leads. If there are any parts stores, especially NAPA you might find one that stocks an ECU connector pigtail

With a 4 pin ECU this is easy:

You need about 5 clip leads from radio shack, let's eliminate them one at a time

A...Bottom left, carefully clip a lead from ECU to coil NEG

B...One pin CW, clip a lead to that pin, this will go direct to battery

C...Clip onto top ECU terminal, this goes to the insulated distributor (recessed) terminal

D...Clip one lead to right hand ECU terminal, this goes to the exposed distributor (male) terminal

E....Run a wire to coil positive, and hook that and "B" to your battery for testing



Ignition_System_4pin.jpg
 
He got er fixed, Steve. Called me on the phone. Sounded like it was a bad Chineseo replacement if I remember.
 
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