I was driving home from work and it just died so when I got it home I started to look over everything. I took the ignition coil wire off the distributor and stuck it next to my alternator and turned it over. About every fourth revolution I would get a spark. My father thought it was the ignition switch because he had this problem when he was a kid and so I changed it out and it made no difference what so ever. So then we thought it was the brain box and since I have lifetime warranty on mostly everything under that hood I changed it out and then the spark changed to being intermittent it would spark twice then stop then spark a few times in a row then stop again. So we jumped the positive terminal on the coil from the alternator and nothing so we swapped that as well and she started up right away. It was a crappy idle for a bit then as it warmed up it somewhat went away. So I drove it to work and on the way back it died again then caught back up and idled very rough then just died. Now I have no spark and I cant figure this out at all.. Everything else was changed about a year and a half ago and I have seen nothing wrong with anything. I pulled everything off and plugged it back in about five times to clean the connections and feel for how tight everything was. The car is a 1973 dodge dart custom 225 /6. If you guys have any questions please ask!!
slant six troubles again..
- Thread starter Smokedya
- Start date
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67Dart273
Well-Known Member
What means "swapped that as well"? You changed the alternator? You changed the ECU once? twice? Or you changed the coil?
Some of what you did made sense.
One area of concern is the distributor and connector. There is almost no current in that connector, as it's a VERY small signal. That connector can be a corrosion / connection problem
Inspect the dist for wear by wiggling the shaft. Inspect for physical damage to the reluctor wheel, and rust and debri stuck in there. Check the gap at .008" (inch). Pickup coils do go bad, but not very often
Hook your multimeter to the dist connector and crank the engine. It should produce about one volt AC. AC, not DC
Make absolutely certain the box is grounded MUST be grounded
Turn the key to run. Use a clip lead and ground first one, then the other, of the distributor connector terminals on the ECU end of the harness. One of the two should produce one spark each time.
Take some voltage measurements. Measure coil + and coil - voltage with key in run. Coil - (NEG) should be very low, less than 1 volt. Coil + should be somewhere between 5 and 10V, this will vary.
Do you have ANYTHING hooked to coil NEG besides the one ECU wire? Tach? Radio condenser? UNHOOK it, so that ONLY the one ECU harness wire is hooked to the coil
Frankly, at this point, if I read this right, you are down to the coil, distributor, and wiring harness issues.
I also saw a post you put with the all the ohms and voltage reading of everything in the electronic ignition and for the life of me I cant find it again. I wanted to go through and test everything to find the problem.
cudajim
cudajim
You do realize "ohms" is a unit of measurement of resistance don't you? You measure voltage in volts and resistors or resistance in ohms.
67Dart273
Well-Known Member
You've eliminated quite a bit. Do you know if the box is 4 or 5 pin?
If it's 4 pin, then you don't need a 4 pin resistor.
Frankly, you are getting down to distributor troubles.......so........
minor problems in the small harness "piece" that feeds the box / resistor / distributor
the distributor connector, corrosion
problems in the pickup, IE gap, wear, bad pickup.
Junkyards? It really PAYS to have a spare distributor. Parts store rebuilds should be cheap for the slants, keep your old core for a spare if you can fix it
And last.........have you actually checked, is the rotor turning? The slants (most? all?) have a plastic distributor drive gear, and they do fail sometimes)
Yeah I pulled it a few days ago when I thought my timing was off. The guy we got the car from some how broke the timing marks off... And the box is 5 pin. I'll check the drive gear again just to make sure that isn't the problem. So just to clarify this the resistor goes bad the car will not run unless the key is fully engaged correct? I just want to make sure I have this right as well.
BillGrissom
Well-Known Member
If the ballast resistor breaks, you will get spark while cranking, but it dies the second you release the starter. For testing, run a jumper from the alternator out stud (or starter relay stud) to coil+, like you did. That applies 12 V direct to the coil, bypassing the key, bulkhead, ballast, etc. Don't run long that way (1 min) or the coil and ECU will get hot.
I suggest getting an in-line spark tester from Harbor Freight ($5). I carry one in all my cars and got us home from an "engine died" condition - failed Crane XR700 box, had a spare box in the trunk. You can also use a clamp-on timing light to check sparking. I use that even on my newer distributor-less cars when it seems I have a mis-fire (helped me find a bad coil pack once). Both are better than your test because they verify spark in the "as running" condition.
Just for kicks, run a jumper from the case of your ECU to BATT-. Even if you get a good case to gnd, you may have a bad frame to BATT- or engine to BATT- ground, which would make it miss. My money is on the pickup gap in the distributor, perhaps from a wobbly shaft.
I suggest getting an in-line spark tester from Harbor Freight ($5). I carry one in all my cars and got us home from an "engine died" condition - failed Crane XR700 box, had a spare box in the trunk. You can also use a clamp-on timing light to check sparking. I use that even on my newer distributor-less cars when it seems I have a mis-fire (helped me find a bad coil pack once). Both are better than your test because they verify spark in the "as running" condition.
Just for kicks, run a jumper from the case of your ECU to BATT-. Even if you get a good case to gnd, you may have a bad frame to BATT- or engine to BATT- ground, which would make it miss. My money is on the pickup gap in the distributor, perhaps from a wobbly shaft.
I'm going thru similar problems ,did you check battery voltage? mine is 15.5/16.0 volts. its causing the coil to over heat and I've been trying to get my wiring fixed , but mine is acting just like you describe .
BillGrissom
Well-Known Member
teringer,
High voltage is due to bad connections anywhere between IGN1 and the voltage regulator (most likely the bulkhead connector) and/or between the case of the voltage regulator and BATT- (most likely the rusty sheet metal screw).
High voltage is due to bad connections anywhere between IGN1 and the voltage regulator (most likely the bulkhead connector) and/or between the case of the voltage regulator and BATT- (most likely the rusty sheet metal screw).
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