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Cyl 1 and 2 misfire


January 5, 2016
Reaction score
City, State
Oklahoma City
Year, Model & Trim Level
1998 Ford Expedition
I've been having a minor misfire since I got my 98 Sport three years ago. Short history, I replaced the intake gaskets when it threw PO171 and PO174, had the transmission rebuilt, replaced the throttle sensor and its wiring harness (could not get a steady TPS% reading even with a new sensor), and a few other things that probably don't make a nickel's worth of difference.
The AAMCO guys informed me I had a pre-cat exhaust leak on the passenger side. I said ok, I'll fix it later.
Torque pro shows me cylinders 1 and 2 are misfiring some, ~300 misfires each on the way home (30 minute trip).
Manifold vacuum is 25.2 steady, so the gaskets and hoses are still good. New plugs and wires are sitting at the post office. Fuel and air filters were replaced on schedule. ATM the vehicle has the exhaust leak and a minor oil leak elsewhere.
What struck me as odd is both 1 *and* 2 were misfiring, #3 was not. I think it's coincidence and both of the plugs may have been shorted out by leaking or spilled coolant or washer fluid. Maybe even condensate from the accumulator leaks in there--I never insulated the new one when I installed it.It'ssible #1 got doused in coolant when the water pump started leaking (that's been replaced). If the coil pack was bad, I'd have misfires on paired cylinders.
I plan to install the new plugs and wires when it warms up. Aside from the fact the old plugs and wires have been there since oh, about 1806, is there any reason those two cylinders would misfire next to each other, or just strange coincidence?
BTW, there are no codes, pending or mature. I had to do a double take on startup just to make sure my check engine light hadn't burnt out.