Electronic ignition diagnostic
The patient is my 1975 Dodge Dart. Since about three weeks, the engine is intermittently difficult to start, no matter hot or cold. This week, the car stalled in traffic. Restarted just long enough to let me pull on the side and stalled again. Hood was open for a few minutes, seems to cool down, and started again. I thought about setting aside the carburetor, it's new from last year and all is well. So I did electrical tests, especially since I'm suspicious of the ignition system since I had to change two coils in the last three years.
I religiously followed the manual and did the prescribed tests.
- ignition coil 2.5 ohms primary and 10580 secondary (blown coils went under 10000 ohms)
- ECU box properly grounded, ohmmeter tested also
- distributor pickup coil 286 ohms, should be between 150 and 900 ohms
So far, so good, but testing the ecu wiring harness cavities... (battery voltage 12.87v)
- available voltage at cavity #1 should be within 1 volt of battery voltage, got 11.30v
- available voltage at cavity #2 should be within 1 volt of battery voltage, got 11.35v
- available voltage at cavity #3 should be within 1 volt of battery voltage, got 11.37v
Is these low readings serious? The manual says nothing. Something bad is going on?
The patient is my 1975 Dodge Dart. Since about three weeks, the engine is intermittently difficult to start, no matter hot or cold. This week, the car stalled in traffic. Restarted just long enough to let me pull on the side and stalled again. Hood was open for a few minutes, seems to cool down, and started again. I thought about setting aside the carburetor, it's new from last year and all is well. So I did electrical tests, especially since I'm suspicious of the ignition system since I had to change two coils in the last three years.
I religiously followed the manual and did the prescribed tests.
- ignition coil 2.5 ohms primary and 10580 secondary (blown coils went under 10000 ohms)
- ECU box properly grounded, ohmmeter tested also
- distributor pickup coil 286 ohms, should be between 150 and 900 ohms
So far, so good, but testing the ecu wiring harness cavities... (battery voltage 12.87v)
- available voltage at cavity #1 should be within 1 volt of battery voltage, got 11.30v
- available voltage at cavity #2 should be within 1 volt of battery voltage, got 11.35v
- available voltage at cavity #3 should be within 1 volt of battery voltage, got 11.37v
Is these low readings serious? The manual says nothing. Something bad is going on?
