Ignition Module Testing

[CdnCutlass]

I have two HEI 4 pin ignition modules. One is a stock replacement and the other is a Pertronix Flamethrower. I went to a local auto parts store and had them both tested as my HEI ignition failed and I had no spark with the Pertronix Flamethrower kit installed.

After testing them both on the Wells machine repeatedly so they got hot enough to better simulate real conditions, the Flamethrower failed on dwell. I know that aftermarket modules have more dwell, would this lead to a faulty test or is the module no good?

Does anyone know how to test a pickup with a multimeter to see if it's any good?

 

[foxtrot]

To test the pickup coil I would start by disconnecting it. Measure each leg of the coil to ground with the dvm and make sure that you have infinite resistance. Also check the resistance between the two legs do the coil and make sure that you have between 700 & 1500 ohms of resistance.. Good luck.

 

[CdnCutlass]

To test the pickup coil I would start by disconnecting it. Measure each leg of the coil to ground with the dvm and make sure that you have infinite resistance. Also check the resistance between the two legs do the coil and make sure that you have between 700 & 1500 ohms of resistance.. Good luck.

Pickup coil tested good.

 

[foxtrot]

The HEI ignition modules usually have a low failure rate weather aftermarket or Delco. I would have to say that both modules should pass the test.

The failing modules I've seen over the years have had thermal issues and stopped working when hot. One the module cooled off, it stared working again.

 

[CdnCutlass]

The stocker passed no problems even when hot. The Pertronix flamethrower module I had failed on dwell when it got hot after testing a few times. I just wondered if the tester did not account for more dwell found on aftermarket modules.

 

[foxtrot]

If it failed when it was warm, then the module is defective.

The ignition module characteristics should only change a few percent between cool & warm temperature...

 

[pontiacgp]

Not all oem modules are the same, the best module I had when I used the HEI was in a distributor that came from a ZZ4 engine. The engine developed a problem with the car shutting down after about 1/2 hour and it would restart after I let the engien cool down. I thought it was the module so I changed it for an aftermarket brand. That module lasted no more than 5 minutes so I tried another oem module but that didn't last much longer than the aftermarket module. The problem and it turned out to be the coil that was faulty and was overheating the modules casing them to shut down and reset after they cooled. The module from the ZZ4 was also curved differently than a stock one and it could handle the overheating issue caused by the coil better than any other module I tried

 

[Bonnewagon]

Are you using dielectric grease under the module to mount it? The grease acts as a heat sink, and the module will overheat without it.

 

[foxtrot]

Not to be a no-it-all but the grease doesn't act like a heat sync it aides in heat transfer. :lol:

 

[Bonnewagon]

That's what I meant. 😳 Hey, GM spent bundles on warranty calls before they figured it out!