71 Charger 500 Ignition problem

[Uncle Bob]

The Charger 500 (383 Magnum, 4 bbl, automatic trans) left me stranded last weekend at cruising the coast event, shut off at red light and wouldn't start. I had noticed an intermittent skip in the engine while driving, before it shut off. Coil was very hot, was able to find a coil and ballast resistor so I changed out with no luck. Could not locate ignition module from any of the local stores. A friend came and trailered me home. I robbed the 5 pin module from my old power wagon when I got home, the sealant in the back was nearly totally disintegrated but it worked and car fired up. Did a test run and everything fine for about 5 miles then I noticed the skip again. Called my local NAPA store and ordered new 5 pin ignition module, installed and did test run, same results after about 5 miles of course everything is at running temp when I notice the skip, noticeable more at 30-45 mph constant speed. After returning home checked coil it was pretty hot and ballast resistor was extremely hot but engine hasn't shut down again, but am concerned about trusting it very far from home. Anyone have any ideas. I did talk to a fellow the other day at show who said there was a conversion available for the ignition to keep it very near factory appearance but is upgrade, anyone know of this or have any suggestions what to look for next.

 

[Dennis H]

Does the 71 have the bulkhead connector? Pull it apart and spray it wih contact cleaner. First, snug the battery cables. Good luck.

 

[nm9stheham]

The ballast will typically run a bit on the hot side. The coil will be warm. With the skipping, I would suspect:
1) Coil; they will often be erratic when they are failing. Seeing as this fails after 5 minutes pretty consistently, this is a possible symptom of the coil failing.
2) Pins in the connector to the ECU; they are round and can get spread with erratic contact
3) The reluctor gap in the distributor needs to be checked; that's probalby not it, but needs checking just to be sure. Gap should be .008" from reluctor face to the little 'peaks' on the distributor 'cam'.
4) Ground under the ECU MUST be good; always clean and re-work the ground with ignition issues. Again, probalby not it, but always check this.

Questions:
- After it first failed, did it want to fire at all when you tried to crank it, or was there just no attempt to fire at all?
- Do you have a voltmeter? I ask since some basic voltage measurements in the ignition circuit will help eleminate some issues.
- Does the ignition key or the steering column area are get wartm anywhere?
- Are your headlights unusually bright?

Yeah, this is going to keep failing 'til you run it down, IMO.

 

[71charger_fan]

When mine did that, it turned out to be a very old battery positive cable with a great deal of corrosion inside the plastic coating. After the car would warm up and I hit a bump, the engine would often cut out. A new cable fixed that, but that was likely more of a freak thing.

 

[Uncle Bob]

-After it failed would not fire until I replaced with a used unit off my old power wagon
-yes I have a volt meter
-have not checked column or key but haven't noticed anything
-headlights seem ok but will check

Question my ECU unit is a 5 Pin which I was able to get a new 5 Pin, but the ballast resistor is a 2 prong, been reading that a 5 Pin uses 4 prong, and 4 Pin uses 2 prong, but my old harness is set up for 5 Pin with 2 prong resistor
And thanks for the advice---I give out but never give up

 

[nm9stheham]

Hmmm, sounds like someone changed the ECU to the later 4 pin at some point. Ca't recall whne they went to the 4 pin, but if in '72, maybe you have a late production '71.

One of the pins on the 5 pin ECU should get voltage through the 'other half' of the 4 prong BR. Are all five pins of your ECU actually connected to wires that go somewhere?? Here is a good diagram for you on how it should hook up: http://www.allpar.com/fix/electronic-ignition.html

With car warmed up and at fast idle, check the voltage across the battery. Should be 13.8 to 14.3 volts or thereabouts. Just check this to be sure the alternator and voltage regulator are working right and not overcharging.

 

[mopar 3 B]

4 pin ecu will work OK with 5 pin harness blast will not have to be replaced. Attach test light to - side of coil and try starting engine if test light flashes off and on with engine rotating low voltage side is OK.

 

[Uncle Bob]

Well I pulled and cleaned connections at the battery, cleaned as many grounding connections as I could find and installed several star washers. Pulled distributor cap cleaned reluctor and checked gap it was about .010 so set to .008, changed one small vacuum cap I found cracked, sprayed carb inside and out with cleaner, checked carb body screws for tightness. Added 1 bottle of rubbing alcohol and some sea foam to gas tank---think I had multiple problems---didn't notice the skip in the engine until after driving awhile after I had filled gas tank, suspect I got some water, unfortunately along with failure of ECU the next morning I was chasing ghosts, took the Charger out for a drive went about 150 miles she ran good, did notice one stumble at a red light when taking off but like I said think water in gas was also a culprit.
Thanks to you all for suggestions.

- - - Updated - - -

I did check column after driving awhile and it was warm at the ignition key. Headlights don't seem unusually bright, but have ordered a spare voltage regulator and am going to pull alternator and have it checked out. See my other post to thread about driving after I did some checks and minor repair work, may not totally have the problem fixed, but will see.

 

[nm9stheham]

Well very good to hear! Everyone is glad to have feedback, 'specially when it is good like this.

As far as the column being warm, you need to get in there to the ignitions switch and connector and inspect. Very likely, the connections are a bit corroded and there may be melting starting in the connector body and wire insulation. If you are lucky, nothing is bad yet and you can head it off. Be ready to replace the ignition switch itself.

Get yourself a voltmeter and add it to your toolbox; it is important on these older systems.