Ahh, help - DSII problem?

M

mysavioreigns

Famous Member
Car won't start - I can't figure out why I'm getting no spark (but I do have gas)

My setup is a DSII distributor with the HEI 4-pin module. I bypassed the pink resistor.

Here's my deductions:

I turn the key to ON:
1. "Switched" items, like the windshield wipers, now work, so the ignition switch is good
2. BOTH terminals of the coil are getting 12V
3. The B and C sides of the HEI module (which go to the 2 sides of the coil) are also getting 12V
4. The W and G sides are NOT getting 12V. Perhaps this is because you have to hit START for it to get the 12V?
5. None of the 3 terminals on the distributor are getting 12V (obviously, because the W and G aren't either)


I had it running a few days ago, everything was fine, came out later, wouldn't start. I checked a wire and it was kind of loose, so I put a new terminal on it and it started up again. Now it's back to no spark AGAIN and I can't figure it out.

Please ask lots of questions to help me figure this out :)
 
W & G should not have 12V. They go to the pickup in the distributor and are not powered. The third wire from the distributor is a ground.

Only the B terminal is powered. The C terminal goes to coil negative.

The duraspark/GM combo is dead simple, electrically. The reluctor and pickup create an alternating current signal that is sent to the module whenever one of the reluctor lobes moves past the pickup. That signal is then used to trigger a transistor to switch the coil "off" and sends the coil negative to ground. Everytime that happens, the coil field collapses and you get a spark. There is some other stuff in the module that controls dwell, etc., but basically, that's all there is to it. It's an electronic version of points.

Hook it up like this, make sure there is 12V and good connections, and add the ground on the distributor (not shown on this diagram).

HEI_small.jpg
 
Yea, I have it wired up like that - the third wire (ground) is wired back to the ground on the HEI module. I just can't figure out which piece of the equation is bad.

Correct me if I'm wrong (and the car is wrong too) but shouldn't both the + and - sides of the coil be reading 12V if the key is in the ON position?
 
mysavioreigns":1pasyze5 said:
Correct me if I'm wrong (and the car is wrong too) but shouldn't both the + and - sides of the coil be reading 12V if the key is in the ON position?
Click to expand...

Yes.
 
good...and darn...

If that's true, the then coil should be good. And the ignition switch and the ignition module. What does that leave? The distributor? That doesn't make sense...this car ran fine two days ago darnit.
 
mysavioreigns":3h2mypst said:
good...and darn...

If that's true, the then coil should be good. And the ignition switch and the ignition module. What does that leave? The distributor? That doesn't make sense...this car ran fine two days ago darnit.
Click to expand...

That does not mean the coil is good.

If you aren't getting any spark, it is either the pickup coil in the distributor, the ignition module, or the coil.

Assuming you have everything hooked up correctly.

Do you have the ignition module sufficiently heat-sinked?
 
Bort62":2ltfmktw said:
That does not mean the coil is good.

If you aren't getting any spark, it is either the pickup coil in the distributor, the ignition module, or the coil.

Assuming you have everything hooked up correctly.

Do you have the ignition module sufficiently heat-sinked?
Click to expand...

Yea, everything is hooked up correctly, I'm sure of that. You might be onto something with the heat-sinked-ed-ness. Here's a little breakdown of what happened.

It wasn't starting, and I figured I had a lifetime warranty on the HEI module, so I went and exchanged it. After I got it back home, I didn't take the time to properly mount it to the heat sink, because I thought (maybe I'm wrong here) that it just needed to be on there to dissipate heat (i.e. after running for a few minutes); So, I guess I need to mount it on there securely and see what happens.

Any other things I should look at though, just in case?
 
mysavioreigns":3sq3vtfv said:
So, I guess I need to mount it on there securely and see what happens.
Click to expand...
I could be wrong but I think the HEI module has to be mounted so that it is grounded properly.

-ron
 
mysavioreigns":33k43mv5 said:
Bort62":33k43mv5 said:
That does not mean the coil is good.

If you aren't getting any spark, it is either the pickup coil in the distributor, the ignition module, or the coil.

Assuming you have everything hooked up correctly.

Do you have the ignition module sufficiently heat-sinked?
Click to expand...

Yea, everything is hooked up correctly, I'm sure of that. You might be onto something with the heat-sinked-ed-ness. Here's a little breakdown of what happened.

It wasn't starting, and I figured I had a lifetime warranty on the HEI module, so I went and exchanged it. After I got it back home, I didn't take the time to properly mount it to the heat sink, because I thought (maybe I'm wrong here) that it just needed to be on there to dissipate heat (i.e. after running for a few minutes); So, I guess I need to mount it on there securely and see what happens.

Any other things I should look at though, just in case?
Click to expand...

If your current module is not heat sinked, it will be destroyed after a few minutes of running.

Is the module properly grounded? if it is just floating there it will not work.
 
At the moment, I have a ring-lug grounded to the HEI module, which is attached to the ground wire on the distributor. So that should properly ground it.

But, the module (at the moment) is not really attached to the heatsink; just sitting on it. I'll tie it down good to the heatsink.
 
mysavioreigns":1txd7ceb said:
At the moment, I have a ring-lug grounded to the HEI module, which is attached to the ground wire on the distributor. So that should properly ground it.

But, the module (at the moment) is not really attached to the heatsink; just sitting on it. I'll tie it down good to the heatsink.
Click to expand...

Make sure your ground is of sufficient magnitude. There is a good amount of current trying to ground there...
 
Just to be clear, C terminal on the module should not connect to anything but the - terminal of the coil (a tach would be the only exception).

Distributor not turning you should not read 12V between B and C

Look close at the modules, they ground through the body. Some have a rivet like thing and a tab going through one of the mounting holes, this is where you want to hook your ground. On mine I grounded to the black dizzy wire and to a body mount.

If W & G are flipped it will just fire at the wrong time. IF you spin the dizzy with a digital or millivolt meter hooked to Orange & Purple you should see pulses. With no spinning you should get a steady ohm reading.
 
The 2 black wires you see on the left under the screw are the grounds, one goes to the DS2 the other goes to the body. Under those two next to the red is the black that goes direct to the - of the coil.

There was a wrong drawing out there and another one that was miss leading depending on how carefully you read the text. This photo is correct.

hei2.jpg
 
fordconvert":a09q1qhp said:
Look close at the modules, they ground through the body. Some have a rivet like thing and a tab going through one of the mounting holes, this is where you want to hook your ground. On mine I grounded to the black dizzy wire and to a body mount.
Click to expand...

Awesome thanks TJ. That's just how I have mine, except I don't have a 2nd ground going to the body. I think I will definitely hook that up and try it again. Also, I have my heatsink in almost the exact same configuration as yours, up under the K-bar railing thing.
 
The module will get too hot to touch after even just a few minutes. It really needs a heat sink and dielectric grease to survive. The heat sink doesn't need to elaborate; just mounting it to a sheet metal panel is fine.

And I can't overemphasize the requirement for a good ground to the module.
 
fordconvert":38o03ofi said:
Distributor not turning you should not read 12V between B and C
Click to expand...

This is incorrect. With the distributor stationary, the module is "open" and as such the + and - terminal of the coil are both open to ground with 1.5/3.0 ohms between them.

Because no current is flowing in this situation, the positive and negative terminal of the coil will read 12v.

EDIT: I see what happened here, correct, you should not read 12v between the negative and positive terminal. (alternatively, B and C if connected properly)

However, both the negative and positive terminal should read 12v when referenced to system ground.
 
I'm still not sure though, why I wouldn't be getting spark...here's why:

If I have a ground from the HEI module's "rivet" thing to the black wire on the distributor, and the distributor grounds through the block why wouldn't that be sufficient ground?
 
mysavioreigns":2gxvmy8w said:
I'm still not sure though, why I wouldn't be getting spark...here's why:

If I have a ground from the HEI module's "rivet" thing to the black wire on the distributor, and the distributor grounds through the block why wouldn't that be sufficient ground?
Click to expand...

Well, in reality - it should work. But:

Not all grounds are created equal. Think of it as water pipe. Current is flow rate.

To pass a lot of current, you need a big pipe. Your wire from rivet to distributor to block to ground is too small of a pipe.

I don't think that is your problem, but it's not an ideal setup and could cause all sorts of weird ignition issues.
 
Thanks, good thinking...heh, "weird"

Weird is what happened last night. I had my test light grounded, checking for 12V hot (with the key turned to ON).

All of a sudden, the fan turned like 1/4" real quick and stopped. That happened twice at 2 totally different occasions so I couldn't figure out why...
 
mysavioreigns":1hvnpprh said:
Thanks, good thinking...heh, "weird"

Weird is what happened last night. I had my test light grounded, checking for 12V hot (with the key turned to ON).

All of a sudden, the fan turned like 1/4" real quick and stopped. That happened twice at 2 totally different occasions so I couldn't figure out why...
Click to expand...

Know a good Exorcist?
 
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