I have no spark car wont start...

[coreydmc]

Ok Guys I need help! My car has no spark and wont start.. I just replaced the bosch Ignition coil with a new one and that did not help. I removed a spark plug from the cylinder, plugged it back into the spark plug wire. Than I had my wife try and start the car while I grounded the spark plug to engine block and I have no spark. Where should I start troubleshooting?

[jmpdmc]

Do you have the Technical Information Manual? If so, turn to page 126 for a diagnostic chart. It might be available on line to view. If not, I will let someone with more experience answer in detail.



Jeff

[coreydmc]

no i dont have the tech manual....sorry

[sdg3205]

Here ya go!

http://dmctalk.org/showthread.php?102-Workshop-Manual

[coreydmc]

I just replaced my coil with a new one from DMCH. Now i took out my voltmeter and measure the voltage on the coil lugs. With the ignition switched on I get 2.5 volts. When i try and start the car the voltage goes down to 2.0 or 2.1 volts. Also with the ignition switched on I am getting a loud buzzing sound from the idle low speed regulator. Is this normal?

[Bitsyncmaster]

I just replaced my coil with a new one from DMCH. Now i took out my voltmeter and measure the voltage on the coil lugs. With the ignition switched on I get 2.5 volts. When i try and start the car the voltage goes down to 2.0 or 2.1 volts. Also with the ignition switched on I am getting a loud buzzing sound from the idle low speed regulator. Is this normal?

When your cranking the starter the coil voltage should be higher than what your seeing but I think even with 2.0 volts you still should get spark. You can try to bypass the resistors just to see if it will start but don't run like that for very long.

With your key on you read a low voltage because the current is continuously flowing through the coil. When your cranking the car the current should be switching and half your resistor is bypassed.

You may have a bad ignition ECU if you don't see a higher voltage when cranking the engine.

[coreydmc]

is there anyway to test the ignition ECU?

[Bitsyncmaster]

is there anyway to test the ignition ECU?

There is but you need equipment to power it and feed an input signal.

Best way is to swap it with another owner just to see if that the problem.

[coreydmc]

I decided to take the drivers side compartment cover off behind the drivers seat and probe around. I unplugged everything in there and cleaned the contacts. Even the ECU module. When I put everything back together the car started right up. While the car was running i decided to test the probes on the coil pack. I was getting a low reading around 1.something. What reading should I get when testing this when the car is running? I also checked the positive battery terminal on the right side bulkhead in the engine compartment while the car was running and I got 14 volts.

[Bitsyncmaster]

Depending on your meter (most display average value) you should read 4 to 6 volts with the engine running with the meter connected to both coil terminals.

[coreydmc]

i will check again tomorrow with another meter. If i am still getting a low reading with the car running whatelse should I check for?

[content22207]

Battery voltage into the resistor grid.
8-10 volts after the first resistor (which is bypassed during cranking -- that side of the grid also has battery voltage while the starter motor is spinning).
6-8 volts out of the grid (8-10 volts out of the grid during cranking).

Ridiculously low voltages even by 1970's American standards, but that's the way DMC configured the car (ignition can be upgraded to HEI, which markedly improves overall performance, including starting).

Bill Robertson
#5939

[coreydmc]

im not sure i follow you. what should I do?

[content22207]

Measure voltages at your resistor grid first.

Then measure voltage at the positive coil terminal.

If voltages are OK, put an ice pick light on the negative coil terminal and see if it flashes on & off as the rotor button turns.

If the ice pick light stays constantly illuminated, you either have an ECU failure, or something has gone wrong inside the distributor (to test the pickup coil, run resistance through it -- about 600 ohms IIRC -- then watch the meter as the rotor turns. You won't be able to read anything meaningful without an oscilloscope, but you will see the numbers jump all over the place which at least confirms that the pickup is not dead).

Bill Robertson
#5939

[coreydmc]

ok i have a test light. so i will put the ice pick park on the negative lug on the coil while I attach the test light clip to the positive battery cable right? and it should flash on and off as the rotor inside the distributor cap turns correct?

[content22207]

If it flashes on & off as the starter motor turns the engine, your distributor pickup and the ECU should be OK.

Bill Robertson
#5939