No Spark

[Pomorza]

Hello all

This past tuesday my lovely Z (who I'm thinking of calling Christine at this point) died on my way to school. She wouldn't start (kept cranking over but not starting). Today I finally got around to working on her. I pulled the coil wire off from the dizzy and held it to the intake manifold while my friend cranked the motor. Nothing, no spark that I could see. So my question is this, what exactly controls spark on the Z, is it the coil itself or does the dizzy somehow tell the coil when to fire? I have an 81ZX dizzy (matchbox) in the car as I updated it a few months ago (great upgrade for reference).

Thanks

Jan

[black gold man]

Ignition Module on side of zx Distributor. Your stock Ignition Module is under dash.

[Zed Head]

I linked to this thread in another one but didn't reply. bgm is right, that if you have the 81 distributor with the "matchbox", the matchbox is the what produces the spark. They're very expensive to replace. Why did you swap the ZX distributor for the stock 76 electronic setup?

There are actually three main things that "produce" the spark - the pickup coil and iron rotor in the distributor, the ignition module, and the coil. They can all go bad, but the module is the most sensitive.

You could wire in a GM HEI module. It's popular because it's cheap and does the same thing the original ignition module does. It takes some wiring modification though.

[Pomorza]

Thanks guys for the replies

I have a spare 81 zx dizzy so I'm going to replace it tomorrow and see if anything gets better. I replaced the old system as I upgraded my injection and needed a better system for it.

Thanks

Jan

[SteveJ]

Rockauto does carry replacement ignition modules.

[Pomorza]

Guys

This past saturday I spent about two hours today rewiring my ignition system. Have a 16 gauge fused wire (20A) running to the coil through a relay that is wired to the ignition switch. When all was said and done I started said Z and it ran for about three minutes. It then had a misfire for a few seconds and then the throttle stopped responding and bam car died. Pulled the coil wire and held it to a ground (the intake manifold) and nothing, no spark nothing. The distributor is new (rebuilt unit from the auto parts store), the coil is a MSD blaster II. Any ideas would be great.

Thanks

Jan

[Pomorza]

Update:

This afternoon I went out to look at the Z again. She started! and ran for about a minute or two and then died (no spark again). I unplugged the battery and went to work on checking fuses and wires and such. (about 15 minutes). Hooked the battery back up and bam spark!. Held the coil wire to the shock tower bolt and had nice orange spark. Car ran again for about 1 minute then died (lost spark). I had my battery and alternator tested (the battery failed to hold charge so I bought a new one). Still no starting.

Could the dizzy or the matchbox (ignition module) be bad again? I just bought the dizzy a few weeks ago.

Thanks

Jan

[Zed Head]

That's two of three that you've swapped. The coil is left. I've heard of cases where the heat of usage will open up a broken wire in a coil. You might check the resistance on the primary (coil + to coil -) and secondary (coil + or - to the center wire) circuits before and after the problem. If it's the coil they would check out okay, then not okay.

[Pomorza]

That's two of three that you've swapped. The coil is left. I've heard of cases where the heat of usage will open up a broken wire in a coil. You might check the resistance on the primary (coil + to coil -) and secondary (coil + or - to the center wire) circuits before and after the problem. If it's the coil they would check out okay, then not okay.

Zed Head,

I'm running a different coil then when the problem first occured. When the car first died I was running a stock 81 ZX coil. I swapped this with a MSD Blaster II coil today. (sorry if I didn't mension that). So what you're saying is that if the resistance is the same before and after the test then the coil is the issue?

Thanks

Jan

[Pomorza]

Hello again all

This afternoon (~noon MST 81 outside and no humidity that's noticable). Went to test the primary and secondary resistance of the coil as suggested by Mr. Zed Head suggested. I placed the DMM on the terminals and got a reading (~0002 on the 200k setting, I think my DMM has a recently (today) broken screen). I pulled the coil wire out of the coil and measured the negative to the center resistance (6.5 on the 200k setting). Put everything back together cleaned up and started the car. Magically she ran, and didn't die, AT ALL. I sat there for about ten minutes waiting for the moment when she looses spark but it never came. I turned her off and restarted and still runs like a top.

Ideas as I'm confused as hell here. Yesterday I was loosing spark every few minutes and lost of for good. Now she runs like new. Can the wire(s) be bad (ignition wires)? Do the match box ignitions sometimes work and sometimes not? If that's the case how come it didn't work at all yesterday but worked like clockworks today?

Thanks

Jan (who is still confused)

[theblackpearl]

i have the same problem on a 77 how did you solve it? any pointers?

[madkaw]

Weak batteries do weird things to transistor units- just ask the HEI guys. Maybe a loose wire also to make matters worse