Diagnosing HEI ignition module and ignition system

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I'm converting a Toyota 20r to an HEI ignition system. I've got it hooked up up exactly as in the picture below with the ground going to the two bolts holding it in place.


The module is a pertronix flame thrower III and the coil is of the same name.

I've checked the ground which is good, the power which is good in both run and start positions. I've checked the impedance of the magnetic pickup in the distributor which is within the proper range.

However, with the ignition on, there is no current going through the coil. Shouldn't the "c" post on the module be grounded when you turn on the ignition so as to energize the coil? I'm worried I may have damaged something by torquing down the bolts securing it to a fender.

I'm getting no spark at the plugs or directly from the coil. Any ideas what might be wrong with either the ignition module or something else?
 
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The "C" post of the module is what provides negative to the coil to charge it. It (the C terminal) will only switch negative once the pickup coil has sent the module a signal and that only happens when a magnetic tooth passes the pickup, creating a small AC signal.

Quick tests- set your meter to AC volts and probe the pickup coil leads- it should generate ACV when you crank the engine over. Next, take a test light, clip the gator end onto the B+ and probe the negative on the coil, then crank the engine- it should blink with each cylinder up.

If you have ACV output at the pickup coil, B+ to the module and ignition coil, grounds to the distributor, but no switched negative to the coil during cranking, then the module is toes up.
 
I'll do those tests tomorrow. I was thinking it might be the pickup coil, but didn't know of a way to test it besides for impedance. Also I didn't know if the module would be charging the coil as long as the ignition was on or not so that's good to know. If I'm not getting ACV from the pickup when I crank the engine I will check the clearance of the pickup inside the distributor.

When you say ground to the distributor do you mean a specific wire? Or just that the engine block is well grounded?

Does it matter which of the two wires going from the distributor go to the W or G post on the module?

Thanks for the help I will post again after I do the tests.
 
The coil isn't charged all the time. If it were, tit'd burn up and you'd never have spark. The module charges the primary winding (creating a magnetic field) in coil by switching negative. When the module cuts the negative, the magnetic field collapses, which induces a charge in the secondary winding- that is the high voltage side.

Pickup coil resistance should be something like 500-1500 ohms, correct?

As for grounds, as long as the block is grounded and there is a good connection from the block to the distributor, you should be fine.

I don't think the W/G wires matter much- but since they are color coded and the module is labeled, I'd try to get it right.
 
It's a Toyota engine and distributor that I want to use with just the HEI ignition module itself as opposed to buying an expensive ignition box. I'm running a separate coil. I was wondering about the coil charging as soon as the ignition turns on because that's the way it works with a points type ignition, if the points are closed. I'm not familiar with HEI. I get how the collapsing magnetic field in the primary coil energizes the secondary coil and all that.
 
According to Haynes pickup coil impedance is 130-190 ohms and i measured this one at 163.5
 
The GM ignition module needs to be mounted to a heat sink. The thin sheet metal of the fender will not keep it cool enough.
 
Ahhhhhhh..... I see now. Yes, like asand1 said- you need a good heat sink to mount the module on. It'll work good enough to see if it runs, but it shouldn't be permanent.

Also, perhaps the pickup coil doesn't put out enough mA to properly signal the HEI module. The pickup coil resistance specs I mentioned was for a GM unit.

I'm curious what you find though!
 
You probably need a new pickup coil.
300px-HEI_pick_up_coil_assy.jpg
 
Except that the o/please is running the factory Toyota ditributor, so it won't look like that.
 
Originally Posted By: asand1
The GM ignition module needs to be mounted to a heat sink. The thin sheet metal of the fender will not keep it cool enough.


It's got a pretty thick piece of steel bar stock between it and the fender for a heat sink. I will see later today if the pickup coil is putting out a signal. Supposedly this has been done before from what I've read on Toyota forums.
 
Original poster is not using a factory HEI setup, he is running a Petronix electronic ignition conversion on a stock points distributor.

I put one of these in my Nova back around 2001, but for the life of me I forgot how it went.
 
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So I was at it again this afternoon. The first thing I did was put a test light between C and B terminals and crank the engine to see if it would flash. Nada, no such luck so I swapped the W and G wires coming from the distributor to the module thinking WTH why not and suddenly I was getting a flashing light on C and B when cranking the engine. Good to know: it does matter which wire goes to which terminal,W or G, at least on this application.
So now I'm using one of those spark checker devices to see if I'm getting any spark from the coil. Nothing with maybe the occasional weak yellow spark. I think: Maybe it's the coil! I check the primary and secondary impedance and it seems fine. However, I do seem to be getting a high impedance path to ground from the secondary winding. I decide to go get an autozone coil to see if it's the coil. I do this and come back, hook it up and still no luck.
At this point I happen to check again to see if I'm getting power and ground to the module and find I'm no longer getting power.
Apparently the wire I was using from the ignition wasn't up to the task of supplying the module with power and finally blew a fuse/melted somewhere. I hook the module up to a relay I am using to power the radiator fan and as soon as I turn the engine over it begins to sputter and backfire!
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WE HAVE SPARK!
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So that's pretty much where I'm at right now. I haven't got it running yet. The timing is set to TDC, but could be off 180 degrees. I also have to double check my plug wire placement. I'll do it tomorrow.
 
Originally Posted By: Robenstein
Original poster is not using a factory HEI setup, he is running a Petronix electronic ignition conversion on a stock points distributor.

I put one of these in my Nova back around 2001, but for the life of me I forgot how it went.


Actually the distributor has a stock magnetic pick up. I'm using an HEI module to control it.

I know what electronic ignition conversion you're talking about though. It has some sort of pickup (magnetic or shutter wheel) and an ignition module built in as far as I can recall. Kind of a slick little device.
 
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