Contour Enthusiasts Group Archives Forums Modifications Zetec Performance Low-down on Zetec ignition timing

Hi folks,

I recently bought a '95 Mystique GS. My other cars are '78 Fords, where the most complex engine component is the Duraspark electronic ignition, so the Zetec's somewhat foreign at this point. Question for y'all:

How is ignition timing set by the engine computer? The manual says to use 87 octane gas; will the timing be automatically advanced if I put in 93 octane? Does the computer adjust base timing, advance timing, or both?

Thanks for your input!

Po

Using higher octane gas without a chip will not advance timing. The gas will just burn slower and hurt performance without a chip.

Base timing is set by the crank and camshaft sensors.

They are not adjustable.

Base timing is well in advance of max advance since the computer can only delay timing, not advance it.

Ignition timing is calculated from "maps" burnt into the chip. Further delay of timing is learned if the knock sensor causes retarded timing on a regular basis.

The only way to change timing is to affect the internal "base" timing delay within the computer or as Kremit said, get a new chip.