One coil not firing. DIS bad?

[Spork]

The coil for the #2 and #6 cylinders is intermittently not firing causing my 91 to run rough. The tach needle will bounce around when this is happening. I replaced the aftermarket coil pack with the original Motorcraft pack I saved and have the same problem. I'm thinking it could be the DIS module. How can I verify this is the problem before I spend a bunch of money on a new DIS module?

 

[kevinspann]

Auto parts store will test a DIS - but good ones can fail that test. Is the DIS broken in any way? How are your motor mounts? I would check the wiring to the DIS and to the coil, since your issue is intermittent.

 

[Spork]

The DIS isn't damaged. Mounts are fine as far as I know. I just removed the DIS connectors to check for corrosion. After re-seating the connectors, I fired it up and it runs fine. Go figure.

 

[Spork]

Started fine this morning, but was sputtering before I could roll out of my driveway. I tried cleaning the contacts on the DIS module with no luck.

 

[kevinspann]

Temperature related by chance? I would still take a look at all of the wiring.

And see what kind of codes are stored in the PCM.

 

[gurucomputers]

Just had the same issue with my 94. Has code 216 "Coil 2 primary circuit failure" replaced DIS and haven't had any problems since.

 

[Spork]

Just had the same issue with my 94. Has code 216 "Coil 2 primary circuit failure" replaced DIS and haven't had any problems since.

I got the coil primary circuit failure code as well. I swapped the coil so I figured I misread the code. I guess I'll but a new DIS module as I seem to have ruled out other suspects.