Engine suddenly cut off when idling

[Clive59]

6 hours ago, hspeck said:

and to add, I tried to hook up the spare powersparks distributor I have(the Ht lead and cable to coil), and hand turned the distributor, but it is no producing any sparks... I don't understand why... another new item failure??

I found that the Powerspark/Accuspark module doesn't do static triggering, you need to turn it at about 1rev/sec and it triggers. Annoying to say the least. But, it does work well when you get timing sorted. I basically worked out where the trigger position was on the workbench, looking at the output that drives the coil on an oscilloscope, beyond most peoples DIY equipment unfortunately.

[hspeck]

1 hour ago, Clive59 said:

I found that the Powerspark/Accuspark module doesn't do static triggering, you need to turn it at about 1rev/sec and it triggers. Annoying to say the least. But, it does work well when you get timing sorted. I basically worked out where the trigger position was on the workbench, looking at the output that drives the coil on an oscilloscope, beyond most peoples DIY equipment unfortunately.

hmm... this is interesting

maybe if the fail occurs again I will pull the distributor and fit in the Powerspark and see what happens.. thanks

[ekwan]

3 hours ago, Andyww said:

The only definite factor seems to be that the coil is overheating and cutting out. 

 

We don't have a definitive diagnosis for this. With the first, he had an oil leak. But we don't know if the leak is age, equipment failure or heat related.

With the second coil, he didn't put his hand on the coil to feel if it's extremely hot when the engine cut out on him. 

3 hours ago, Andyww said:

I am not sure about turning a distributor by hand on these systems. They dont use an optical sensor, its a coil and magnet, or might be hall-effect, cant remember, so it would be speed-dependent. Unless the shaft was rotating at a certain speed the output of the sensor coil may not be enough to trigger the unit. 

 

I believe Lucas would use a VR sensor both for amplitude-speed sensing as well as the absence of an external magnet that is capable of picking up metal bits leading to erroneous ignition timing.

Edited May 23, 2019 by ekwan

[ekwan]

11 minutes ago, hspeck said:

hmm... this is interesting

maybe if the fail occurs again I will pull the distributor and fit in the Powerspark and see what happens.. thanks

Sent you a PM

[hspeck]

OK, so I swooped back to the Lucas coil (the one in the car now is a Viper) and the car could not start. I was happy for a while and when I fitted the Viper, the car still could not start. 

Unfortunately I forgot to bring my spark plug socket home. Tomorrow I will check the spark from the coil as the voltages were correct. 

Incidentally, can I know how I can crank the engine and check the sparks alone? I sort of read somewhere that I can run a wire from the battery to the starter to remotely crank the h engine? 

Thanks 

[hspeck]

So, looking at the circuit diagram, it is a relatively straight forward connection. 

To eliminate an intermittent wire connection, I am thinking of re-running the wires from the amp to the coil and also to the distributor, and isolating the wires to the rpm relay and rpm limiter. 

This will greatly simplify the circuit, leaving the amp, distributor and coil. 

What do you guys think? 

CircuitDiag.pdf

[ekwan]

2 hours ago, hspeck said:

OK, so I swooped back to the Lucas coil (the one in the car now is a Viper) and the car could not start. I was happy for a while and when I fitted the Viper, the car still could not start. 

Okay, you measured the Pr and Sec resistance of the Lucas coil but the coil now doesn't fire, or perhaps the spark is too weak for the engine to fire up. But the engine runs when the Viper coil is fitted. Is the Primary resistance for the Viper 3 ohms? 

I am wondering whether the CE module has partially failed so that it overheats or breaks down when a higher current draw is required.

Perhaps, it would be prudent to carry out the following checks and report back.

[hspeck]

I did this test and also the rest previously, but I will do it again later. 

I was assuming No. 4 is referring to the case of the amp when I did the test last time. Please correct me if I am wrong. 

Thanks. 

[ekwan]

2 hours ago, hspeck said:

I was assuming No. 4 is referring to the case of the amp when I did the test last time. Please correct me if I am wrong. 

Thanks. 

Yes. If there is voltage between the box/case and the chassis, means the unit isn't properly earthed and that could damage it. The condenser needs to discharge to earth for it to work as intended.

 

Another common issue is that the GM HEI device inside the AB14 heats up more during idle, compared to high speed operation. This is because it limits the current to a low resistance ignition coil at low engine speeds. Problems can be resolved by opening the case, and cleaning and applying heatsink grease between the HEI module and the case.

Edited May 24, 2019 by ekwan

[hspeck]

1 hour ago, ekwan said:

Yes. If there is voltage between the box/case and the chassis, means the unit isn't properly earthed and that could damage it. The condenser needs to discharge to earth for it to work as intended.

 

Another common issue is that the GM HEI device inside the AB14 heats up more during idle, compared to high speed operation. This is because it limits the current to a low resistance ignition coil at low engine speeds. Problems can be resolved by opening the case, and cleaning and applying heatsink grease between the HEI module and the case.

Noted.

Busy day today can only check again later in the evening. 

Thanks

[hspeck]

An unfortunate thing happened.. To me at least

I hooked up my spark tester to check for spark from the coil, using the no. 3 plug wire connected to the coil at one end and my spark tester at the other, and there was no spark. 

I replaced the wires, and lo and behold, the car started. 

I did a quick measure and all voltages and resistance were in spec. 

I even drove the car around and tried to on and off the engine, and it started everytime. 

Guess I might have to wait for the problem to occur again before I can check further ?