Tampa 928s

80 Euro

We have found via testing with a Hei tool that it will not fire to indicate a good voltage.

I have gone through testing per WSM:
Coil Primary 1-15 .5 Ohms
Secondary 1-4 9.6K ohms
4V at pin 15 of coil with key on
Green wire from Ignition module pins 7-31d 680 Ohms
Wires new checked resistance out all OK, new cap and rotor.

I found corrosion on pin 15 12V feed to ignition module, cleaned and tested still no firing of HEI tool.

Shawn had purchased the same tool and tested it on his 82 with the same ignition and it fires. We were concerned that it may have not had enough voltage to trigger it and we were heading down the wrong path.

This leaves a bad ignition module or defective coil, without a high voltage scope there is no way to look at the amplitude of the voltage feed to the coil. Is it possible to damage the ignition module with this corrosion and not completely take it out?

Mrmerlin

check the resistors on the passenger side fenderwell these usually cause the low voltage if one fails

Skiviking

I'm sure you alreay have done this...but double check and clean your positive battery terminals and Neg ground battery terminals and snug them down. I found mine wouldn't start or fire until after weeks of searching I was cleaning grounds...that my positive battery cable was snugged but slightly loose and the neg ground has some oxidation between the terminal. Once cleaned all was good again...hope its that easy for you.

Tampa 928s

resistors
.4 Ohms
.6 Ohms

They both check OK 4 Volts on Term 15 of coil.

Skiviking

By the way....just love the color of your 86....

Mrmerlin

the resistors sound like they are working,
check the screw connections at each end for corrosion though

Tampa 928s

Everything has been checked and double checked all the test points to one thing, bad ignition module. Shawn has a spare coil and module that I will pick up tomorrow, hopefully will know soon what is causing this.

smiffypr

Have you checked this voltage while cranking the starter?

Tampa 928s

80 Euro
I have swapped the Ignition module, coil and distributor and tested for spark on my HEI tester. Shawn's 84 my 86 all fire this thing I am not sure what I am missing.
Has anyone used these HEI testers on an 80's vintage ignition, if so did you test fire it.
I can test with a spark plug it fires I can test with an adjustable spark tester it fires but not on the HEI. I would like to know if this ignition has enough voltage to fire this tester.
I am chasing a skip, have a new cap, rotor and plugs tested everything per WSM, wires look new and ohmed out OK.

Fabio421

FIFY

Mrmerlin

OK what was the last thing you fixed before the engine started running poorly

Tampa 928s

That is a good question since the car is not mine and last worked on 10-Years ago.
Someone started fixing a ton of stuff then quit and it sat waiting to be finished; that's where I came in to the picture. I have over 70-hours in it, as it sits it runs great compared to when I received it, but not perfect. Chasing the last issue which looking for a rock stable idle and smooth acceleration with out surging.

BReyes

I bought a Bell & Howell oscilloscope, and if may help you, pm me. I have to do some troubleshooting on my 996 so I will be around.

Regards,

Tampa 928s

Did some testing after finding plugs 2%3 black I used one of those spark plug testers the type that have a screw to see how far the spark jumps.
The manual says 12 MM number one and 4 were OK number 2 an3 were at 8 MM.
I have a old spare of wires and changed them and will go for a run but this is got me confused.

Fabio421

Mark, I clarified your post a little based upon my conversation with you.