sancho

So my IROC stranded me today...

I had been driving it on the highway for about 45 minutes with no problems and then hit some traffic. Once I came to a stop, the engine stumbled and died. Then I started it, but it stumbled really bad on takeoff--basically no matter how much gas I gave it, the engine just sputtered and was only able to go up to about 5 MPH until it finally started to take off.

After I pulled over and killed the engine, I wasn't able to start it up again (it turned over but didn't fire). I thought that it was probably an ignition module (since I only seemed to have problems once the engine was hot), so I replaced that but it's still the same. I checked spark at the coil using a spare spark plug grounded to the intake and I got consistent spark at the coil. However, when I checked spark at the #1 plug wire, I only got maybe one spark or two per 3 seconds of cranking. I changed the plugs, wires, rotor, and cap only a few weeks ago.

Is it possible that my coil is working but "weak"? Like it has enough juice to create an arc directly on a spark plug, but not quite enough to arc in the distributer and arc the plug at the same time?

pizza_guy

It's possible. I've had a bad ignition coil that actually passed the ohm testing. It sounds like you've already replaced any other probable part lately, so that would be my first guess.

sancho

Yeah, the main reason I ask is that I've got a mechanic over here who thinks it's the rotor. I've changed that within the past few weeks, tho, and it looked fine when I pulled it to change the ignition module. I know what a rotor does and that's why I'm reluctant to think that it is a likely source of malfunction (it is, after all, just a spinning conductor).

Out of curiosity, what kind of resistance should I be getting from the coil (and where do I test it)?

bilms01

If the coil has spark and there is spark from the coil wire to the cap but nothing going to the plugs narrows it down to the the cap and rotor. Check the rotor to make sure the index tab inside that aligns it to the Dist shaft isnt damaged. I have had and seen many rotors where the contact strop comes loose from the plastec after a few heat cycles. A word of advice just because parts are new or replaced recently doesn't mean they didn't fail. Double check and triple check could save you a lot of cussing. First couple rules for troubleshooting anything is 1) verify the problem 2) verify the basics no matter how new or old

sancho

I ended up replacing the coil and it started right up.

I'm not completely sure it wasn't the rotor, however--it did have some black buildup where the brush meets the rotor. I ended up wiping that clean with a dry rag and then applied more dielectric grease to that contact surface.

Thanks a lot for the help!

SpitotRs305

why would you add dielectric grease there? you know that dielectric grease is NOT conductive right

sancho

So I was about to defend that dielectric grease was a conductor; then I looked it up and found that you are exactly right: it's an insulator. No wonder I changed majors out of electrical engineering...

I think perhaps I should go into the dizzy cap and wipe that stuff off. And on that note, what should I put there? White grease?

Thanks SpitotRs305 for pointing that out...