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Hi Eric,
I have a 1973 Dodge Charger with a 440 engine, electronic ignition (circa 1973) and an automatic transmission and a 280H cam.
I built this car for my wife as a gift…but it is unreliable.
The engine stalls when I turn on the lights while in the transmission is in Drive and I hold the brakes down. (Like in traffic).
I was trying to diagnose my alternator by following your video on YouTube, but I can’t get the alternator voltage reading because the engine just dies when I turn the lights on (the video said to turn on all your accessories to check the alternator.. However, I can drive it with the lights on, but I cant be stopped in traffic with the headlights on. Any obvious things I should be checking?
(I have my negative battery cable going to the engine block and from that point on the block I have a ground strap going to my frame and another ground strap to my unibody).
thanks and very respectfully,
Victor
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First quest..
Do the light come on and the engine stalls?
If so, either your ignition or fuel pump (if you have one ) is being turned off when the lights engage.
I would check for 12V at the coil with the lights off, if it’s there, turn the lights on and see if the 12V disappeared.Dodge / Chrysler also used ballast resistor How exactly it is wired into your electrical system I do not remember.
But that may also be a source of your issue.The answer question is yes it does stall after 1-2 seconds when the lights are pulled on in Drive, unless I rev it up to 1500-2000 while standing on the brakes.
It does not do this in park or neutral
I forgot to mention I have a mechanical fuel pumpO-Tay.. scratch the fuel pump ..
Works in P and N but not D at idle….
Possibly something screwy with the N safety….?
Will come back to that.Lets start here…
Need to see if your losing spark when you turn on the lights.
And if so, where.
TroubleshootingTroubleshooting an electronic ignition system is fairly simple. Once it has been determined that there is no spark, there are a few quick checks that can be performed to determine the cause. A DC volt/ohm meter can be used to check the continuity of the pick-up coil. It can be checked at the leads as they leave the distributor, or on pins 4 and 5 of the ECU connector. When measuring the resistance across the two leads of the pick-up coil you should see a 150-900 ohm reading. Always flex the wiring leading to the distributor and to the ECU while checking the resistance to be sure that there are no breaks in the wiring. You should also check for 12 volts at pin 1 of the ECU connector when the ignition is in the “on” position. It is also important that the ECU be securely bolted in place and that bolts provide a good ground to the ECU housing. The only other lead that is connected to the ECU is the “-” lead to the coil, which can be checked to insure that it is not broken.
The other important component of the electronic ignition system is the ballast resistor. It should be checked with an ohm meter and should have 1.2 ohms of resistance. Typically, a failure of the ballast resistor will result in the engine starting, but then dying as soon as the key is released from the start position. It is often handy to have a spare ballast resistor or ECU lying around to use for troubleshooting.
Upgrading or replacing an existing systemWhen replacing a points type system, you will need the wiring harness that goes with the electronic control unit. The installation is fairly simple and the only electrical connection that needs to be made is to the ignition “+” circuit.
If you are replacing an Electronic Lean Burn or Electronic Spark Control system, there are several other things to be considered. While these systems are of themselves, electronic ignition, they do not use the same components as the regular electronic ignition system. The spark advance was being generated by the computer, therefore the distributors lack vacuum and mechanical advance. Many of these distributors also have two pick-up coils and are not usable with a regular electronic ignition system. Additionally, the carburetors that were equipped on these cars may lack a vacuum advance port for a conventional distributor and often need to be re-calibrated for use without the computer.
Check condition of battery cables and grounds from the engine to ECU, and battery ground to body.
The factory ECU is grounded through the body, but is triggered through the magnetic in the distributor with its ground reference to the block, and is susceptible to ground loop problems as current flow increases in the electrical system, the magnetic signal voltage reference can rise past the detection point level in the ECU to where the ECU does not detect the signal.
Normally this shows up as an engine not wanting to start until after releasing the key from the crank position to the run position (starter current causing voltage rise in battery ground wiring.)This assumes the charging system is maintaining good voltage output under load at low RPMs, which could be another issue.
All my old Mopar cars have been converted to use the newer all-in-one distributors with built in electronics, or newer ignition boxes like the MSD6AL or Crane HI-6 triggered by the stock magnetic distributor. These also do away with the ballast resistor.
Makes me wonder if your idle speed is way too low, and the extra load from the alternator is dragging the idle down to the point where the engine can’t keep running. I’d also check the idle mixture, ignition timing and choke function. Could be that each one is just a bit out, but the total combined effect results in a big driveability problem.
Could also be a case of poor alternator output. If the alternator is bad, the extra load from the headlights could be robbing current from the ignition primary side. Also, check your battery connections and chassis grounds for tightness and corrosion. Bad connections could be causing the entire system to be running at below optimal voltage to begin with.
I’ll recheck my connections. it all works if I rev it t0 1500 in neutral. I’ll get some one else to double check my work as well
Update.
if I follow the YouTube video and do the test in neutral at 1500 rpm this
Car off – 12.6V
Idle accessories off- 14 74V
1500 RPM acc off – 14.74 V
all accys on 1500 – 15.1 VThat seems to be out putting way too much at over 15 volts. Bad regulator? Try unplugging one headlight, testing again, then unplugging the other and testing again. Maybe a very high resistance short to ground?
Another test is to charge the battery up good. Take the regulator out of the loop. Run it and see if it still happens
[quote=”NevenSurfac” post=175277]Update.
if I follow the YouTube video and do the test in neutral at 1500 rpm this
Car off – 12.6V
Idle accessories off- 14 74V
1500 RPM acc off – 14.74 V
all accys on 1500 – 15.1 V[/quote]I would check the voltage from the battery negative terminal to the voltage regulator body when all accessories are on. From the info above it looks like ypu may see a few tenths of a volt, when it should be none. This would indicate issuws with the grounding and battery cable connections.
Thanks 451 Mopar,
I Checked the voltage at the regulator and this is what I got
Cold at 1250 RPM (in park, no accessories) 0V at voltage regulator body
Warm at 1500 RPM ( in park lights on) .008V at voltage regulator body
Operating Temp 2000 RPM (in park lights on and AC running) .02 V at voltage regulator body
I only have lights and AC, no radio or any other options installed
So, I’m not sure if .02 is too high, but its not zero.
Does this offer any clues?
thanks!
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