I've had two strange incidents coincidentally connected but wanted to get some input on others experiences. Lately I've been experiencing some slight stumbling of the engine when coming to a stop in my car. It happen infrequently but often enough to warrant a tune up.

Last night I opened up the distributor cap to replace both the cap and rotor. I had to turn the engine over a few time to get through rotor screw to align itself for me to access it. However, the screw was in bad shape. It appeared brittle and corroded and when I exerted some force to loosen it, it stripped. In fact, most of the screws in the distributor looked that way. I'm sure it's been on for at least a 100K miles and possibly more since the distributor,ignitor coil,and unit have not been touched since I got the car. Is it normal to see this type of wear?

Anyway, since I really couldn't take anything off, I decided to put the cap back on. That's when I noticed the engine wouldn't start. Just whee whee whee but engine doesn't catch. I thought maybe I flooded the engine when I was trying to align the rotor earlier. I tried the "floor the gas pedal" method to dry off the chamber and plugs but I wasn't successful. Even after pulling the plugs out for a night didn't help.

So I proceeded to check for spark. No spark on the plug and none on the ignitor coil either. I checked the voltage of the various distributor contact points according to the manual and found all to be at 12.8V except for the yel/grn wire for the pgm-fi ecu to igniter unit. It read at 10.5V. I'm not sure if that's bad or not but at this point whatever I found was useless as I couldn't really take any part off with the condition of the screws. Does anyone know what reading I should have gotten from this?

Anyway, I finally got a replacement distributor and engine fired up fine. I guess it really was on its last legs because a simple taking off the cap triggered its demise.

Now the other side of my question has to do with the dome light. While I was having the distributor issue, the dome light would stay on even when all doors were closed in the "door" (middle) light setting. I just thought that also went since when things go wrong they all go wrong . However, after fixing the distributor, the dome light is back to behaving correctly.

Is there some connection in the electrical system between the distributor and the dome light and/or switch?

Thanks for any feedback.

 

On these systems, it's important to not let the coil fire into an open circuit (e.g. cranking the engine with the cap off or a spark wire disconnected). That is prone to blow out the coil and you have no spark until at least $60 later for a new coil. Either disconnect the distributor power wires before cranking, or turn the engine by hand (put a socket wrench on the crank pulley bolt) with the key off.

There's no connection between the ignition and the dome light other than the grounds. When seemingly unrelated electrical systems start to interact, always suspect a bad ground.

 

mk,

thanks for the response. perhaps, having the coil fire into an open circuit, like you said, sped up its demise (or was the cause). Thanks for the advice. I made sure to put a ground when I checked for spark but forgot to when aligning the rotor.

for the grounds, I know of the ones on the valve cover and tranny. are there any others? I think it's time to replace them with fresh wires.