I was still having the issue of the idle rpm dropping to 300-350 then picking up again.
I've almost ruled out fuel as when it failed I checked and both float levels were midline.

I connected a timing light to the coil to dizzy wires to test. The trailing was firing, but not the leading, then it was, then it was not.
I have switched coils, coil wires, even switched the connectors to the igniters, all with the same result.
The air gap on the pick-up coils in the dizzy was just above 0.5mm (spec at 0.5-0.9mm)

Question:
Can an igniter be intermittent?

I switched the igniters and got leading spark, but intermittent trailing without changing anything else. Sometimes it was constant, nothing, or skipping. I cleaned and tightened the connections on the top of the igniters and the on the coils. Now, the "bad" igniter has no spark on startup, but then does. Both skip ever so often, but no noticeable pattern.

Question:
Is it normal, given the age, that there is a skip/missed fire ever so often at idle?
(It does run again and that's great!!)
New igniters are costly, and I'm not sure if a used one or two would help.


I'll work on the carb this summer when I have more time, and I did find out it is possible to run on only the trailing plugs, but not much fun.

And yes, I saw this thread just last night, but wanted to test more today to confirm.
https://www.rx7club.com/1st-generati...spark-1075585/

Suggestions welcomed.

Thanks.

 

You may have a bad ignitor it is possible that it is failing intermittently. I have experienced this kind of failure several times from ignitors after the have warm/heated up. If you have one good ignitor you can run it in the leading spot.

 

The one itnitor failure I had which left me stranded until i figured out to trigger the EGI by swapping the lead to leading died sitting at a light waiting to turn left and the engine shut down, DRT.

I suppose you could have an intermittent failure to fire, but I'd look closely at the wiring harness and grounds to be sure you're not chasing a bad wire in the leads, possibly also the connection between the metal base of the ignitor where it mates to the distributor. If it's unable to shed heat to the distributor through this interface, it could cause intermittent overheat and cut out igniting - a dab of CPU paste goes a long way.

As you've done, swapping the leading and trailing ignitors identifies the bad ignitor, however.

 

Ignitors can be intermittent, yes. One intermittent trailing on an 84-85 would kill the fuel pump every time it would turn off. I almost didn't make it home.

 

Thanks.

The heat issue is hard to track down, but the CPU paste on the leading igniter was more of a powdery cake. That fits the pattern as the igniter would cut out for 30 seconds to a minute or more, then work again.

Rechecking all the connections and continuity in the harness makes sense as the more I fiddle with everything, the less it fails.

It is better, but not quite ready to get me to work and back.

I'll update this thread if/when it runs without failure.

(New igniters are expensive and used ones may not resolve the issue.)

Thanks again.

 

I had a trailing igniter do this to me years back, and it actually WASNT the connection paste on the back of the unit. It was a lousy contact where the 2 tiny blades plug into the distributor. It was loose for some reason, and I actually had to repair it with solder. I have driven the car for years now since then, and I have never had another problem with it.

 

And I will check those tiny contacts as well.

Thank you.

 

Checked all contacts.
CPU paste on both igniters (thanks to our IT department)
Ignition on both leading and trailing last night.
This morning, the "bad" igniter failed at startup, no fuel pump, carb bowls emptied.
Not reliable.

Ordered used igniters from Mazadatrix.

(Side note: finished the steering linkage. Steering wheel free-play went from 1.5" to less than 1". Can't wait to drive it again.)

Thanks for all the assistance.

 

Got two used igniters from rotoholic.
Installed them, turned the key and instant running.
Smooth, no noticeable misses.
Test drive and full power restored.

Seems igniters can shut down completely, go off for 10-30 seconds, and/or cause mis-fires.

Set the timing at night with a single light outside.
Made the video.

Fun with Timing Lights

 

Congrats and thanks for updating the thread. More info into the Collective....
Stu Aull
80GS
Alaska

 

Glad you worked it out, I saw this but was at DGRR and didn't get to respond.