Irregular missfire, and inconsistent timing make it next to impossible to properly time. The timing, with the coolant sensor unplugged, would jump between eight and twelve degrees, and the exhaust sounded like it was missing a cylinder ever half second to second-and-a-half.

Hall effect pickup shutter blades lose due to worn out plastic holding tabs.

The timing is advanced using a magnetic pickup called the hall effect. It is inside the distributor and can be reached by removing the cap, rotor, and hall effect pickup. What you have left is the base of the distributor with the rotor shaft and shutter blades showing. The shutter blades are held in place by plastic tabs that were melted in place when assembled. Over time these plastic tabs get worn and the blades start to wiggle.

Thanks to some help from Wes Grueninger off the SDML I put together a fix that thus far I can only say is temporary until I catch up with the plastic money bills and get a new high performance replacement, but hopefully it will hold together for six months or more. Basically what I did, was borrowed my dad's propane torch - used for small pluming jobs - to heat a metallic object to remelt the plastic tabs with. At first I wasn't having much luck, because I was using the head of a big, flat headed roofing nail that was more intent on just melting then holding the heat well enough. I started using a long flat head screwdriver with the tip snapped off which held the heat much better, but didn't melt the tabs as uniformly. The non-uniformity of the screwdriver was actually much better because I was able to melt into the tabs much deeper and push the plastic to the edges of the taps where they would grip onto the metal better.

Note: be sure to have a fire extinguisher close at hand any time you are working with fire, or better yet, in the car at all times. It can mean the difference between a few melted wires and/or hoses, and a completely destroyed vehicle; along with everything within five to ten feet of the vehicle. Also, be careful. It's hot! Don't burn yourself <duh>.

After applying the heated screwdriver a few times to each tap - reheating between each application - the blades started to feel much more solid. I did a couple more applications to make sure they were all gripping solidly, but being careful to not melt too much away and ruin it. I also didn't want to play with it too much until I was sure it had a good grip, and even then I only tested it enough to be sure it was holding. After that I apply four small dabs of silicon to the four holes on in the metal to hopefully provide some reinforcement. After letting the silicone sit for a short minute I smeared it around the base of the blades, and over the remelted tabs to smooth it out and help connect everything together. Super glue may have worked better, but the silicone glue is what I had handy.

I gave it time to cool down and dry while I cleaned up and put things away. I made sure everything had cooled down first - didn't take long in the fifty-degree weather - and kept my other screwdriver out until I put every thing back together. I gave the blades a finale check before putting the distributor back together. Since I was under the hood anyway, I also checked the oil, and coolant along with a general visual check to make sure everything looked like it was back in place.

As soon as I was sure everything was back together and put away, I started it up. The erratic missfire seemed to be nonexistent, the vacuum was just a bit higher, and the car seemed to warm up a bit faster. The next step was to check the timing and make sure it was where it should be instead of jumping around all over the place like it was before, and it was closed enough. At this point, I was convinced that the last major problem with this car was mostly and finally fixed; other then replacing the injectors, but that will go under the modifications category.

subject:   RE: SD> Follow the Bouncing Timing Mark -- What's the Cure? and, Lumpy Idle -- Related?
    Date:   Mon, 15 Feb 1999 01:57:45 -0700
   From:  "Geoff Allan" <[email protected]>
       To:   <[email protected]>

Hey, there's a MUCH easier way than this!

I fixed mine in about 92, and it has been fine ever since... just mix up
some good epoxy, squirt it UNDER the shutter, press it down (the tabs will
line it up straight even though it's loose). 1 hour later it's a permafix.

I took a good look at this this summer, and it is actually better than
stock. Solid, stable, tight, and good. Never had another hall-effect
problem!