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Re: 1998 Expedition missing the first half of the firing order
Posted to Technical Discussion Forum on 8/29/2025 1 Reply

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Back in that era, GM ECMs used components called quad-drivers to ground injectors, relays, and solenoids. Generally speaking, it would be very unusual for (GM) to use one QD to ground 4 coils. Usuall... Login to read more.

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