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Old 26-10-2009, 10:28 PM
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Bob the Boss Bob the Boss is offline
Join Date: Oct 2009
Location: Madley in Herefordshire Uk.
Posts: 623
Thumbs up Ford Focus Zetec S, 1.4, W Plate.

Customers complaint, misfire,

Codes PO304 check for misfire on cyls: 3 and 4, if the misfire is on the two cyls: you will need to test out the two coil triggers using a scope.

If the triggers are ok, or the misfire is only one cyl, sub: the coil, do test the leads for high resis:, and arc at lead ends, down plug lead boots, and plugs, check the plugs for black lines running down them, the gaps are wide and so plugs need to good.
The new small type coil pack will fail, it has tight windings, the old big pack was better.
Do not open circ: the coils, or damage to the ECM may happen, and also the coil will arc inside the pick to ground and the pack will be us .
Test for the misfire by using a grounding probe.
If a trigger is missing you will need to test wiring and the ECM. note if a trigger is missing, two cyls: will be out, 1=4, or 2=3, the system is DIS.
Gibbins Motors Technology Uk
The more you know the less you know!!
Bob the Boss forum owner
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