Fiero Ignition System Information
The following is a description of the Fiero‘s ignition system. It applies mainly to the V6′s, but also to the 1984-1986 4 cylinder engines. The 87/88 4 cylinder engines are too different, but 87/88 L4 owners may still want to read on, since they’ll see how their engine is superior to the prior years. I’ll describe the basic operation, problem areas, and how to fix them.
Let me warn you that this may get a little technical…
Everything revolves around the crankshaft (literally). This is the base for all timing. When the crankshaft is a few degrees before Top Dead Center (TDC) on the compression stroke, you want the spark to ignite the air fuel mixture, at the precise timing as determined by the ECM. To achieve this, the timing chain connects the camshaft to the crankshaft. Now, the timing chain streches over time, resulting in a timing that can shift with engine load changes. The valve timing changes too, but a few degrees change in the valve timing are not as critical as a timing change in the ignition system. This is one area where timing gears are better: they don’t stretch. 88′s don’t have the problem at all, since the DIS module picks up its timing directly via a pickup on the crank. There is no stretching or wear. If your t-chain is stretched, well, this is not an easy job and is best left to the professional. But let’s continue.
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