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1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-02-2006, 10:16 PM   #11
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It doesn't matter. Our cars fire each one twice. So 1 and 4 get a spark at the same time. While one is at TDC on the compression stroke, and the other is at TDC on the exhaust stroke. If you switch them, it still works fine.

It'* called the 'waste-spark' method.

The other system, Waste-Spark, is the most common type of direct ignition and it is used by many import and domestic manufacturers. Waste-Spark is the most common system used because it has proven its reliability in marine and motorcycle applications prior to being used in an automotive application.

GM uses four variations of the Waste-Spark system on their engines. The four types are: Computer Controlled Coil Ignition (C3I), Direct Ignition System (DIS), Fast Start, and Integrated Direct Ignition (IDI). These systems have some minor differences, but the system'* overall construction is the same. Each system has each end of the coil'* secondary winding attached to a spark plug. The system fires both spark plugs as a pair whenever the pistons are at TDC in the corresponding cylinders. However, only one of the two cylinders is at TDC on the compression stroke. The other cylinder is at TDC on the exhaust stroke, so the spark is 'wasted'hence the name Waste-Spark.

Waste-spark in a nutshell

In order to understand the Waste-Spark theory, you have to understand a basic electrical circuit. Electricity always travels in a circuit. It leaves its source, performs its job, and returns to its point of origin. The coil secondary winding is the source of the spark for the spark plugs. Therefore, the spark has to return there in order for the circuit to be complete.

Since the polarity of the coil'* windings is fixed, one spark plug always fires in the forward direction (from the center to the outer electrode) and the other plug always fires backwards or in reverse polarity (from the outer to the center electrode). In order for this to work, the two spark plugs for each coil are connected in a series circuit. The spark travels from the coil through one spark plug wire to the plug. The remaining energy travels through the engine block on V-type engines or through the cylinder head on inline engines and fires another spark, backwards, at the mating cylinder'* spark plug. Then, the circuit is completed by the energy returning to the coil via the other spark plug wire. In essence, the second spark plug wire in an EI system replaces the coil'* secondary ground lead on a DI system.
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Old 07-02-2006, 11:08 PM   #12
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Got it all done and figured out... however the car wouldnt stay running at first and it was backfiring out the intake or something. I switched 1 and 4 and all was well. Car still has a bit of a miss at idle, maybe the cat is a little clogged. I changed the plugs, wires, coils, icm, and o2 sensor today. Next is pcv valve and a top engine clean. I also put fuel injector cleaner in it last fill-up.

Anyways, guys, I really appreciate all the fast help I got, especially on a holiday weekend.

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