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Q: Cylinder 1 misfire

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Truck is new to me. It has a misfire on cyl 1. I decided to change plugs and noticed a plug wire was off. I replaced all plugs and made sure all my wires were on & it started real hard & idled worse. If I pull the wire that had previously been off it starts easy & idles like it used too. I don't know how long it had been driven with the wire off. Truck had been sitting awhile before I got it because of a knock which was a cracked flywheel. Please help

My car has 170000 miles.
My car has an automatic transmission.

A: Hi there. From the description you have pro...

Hi there. From the description you have provided, two things come to mind. One, a blown head gasket between cylinders #1 and #3. Two, an intake valve not sealing ie; broken valve spring, burnt valve. Providing spark to the number one cylinder, allows the combustion process to take place, which is affecting other cylinder performance. A compression test and cylinder leakage test would confirm this possibility. Proper diagnoses should be performed. I recommend having your vehicle's #1 cylinder misfire be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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