1998 f150 5.4. Sputtering and stalling when giving gas such as trying to pass on the highway. Changed plugs and 2 bad coils. Noticed when I changed the last coil the plug coming out was wet but no particular type smell. Have rn 2 as of sefoam thru the tank. What to try next.no codes present. Strangely every other day my daughters Nissan altima is doing the same thing but not as frequent and it's coding at auto zone a transmission problem but the transmission folks say there's nothing wrong with it. I'll try whatever you answer on both vehicles.
My car has 200000 miles.
My car has an automatic transmission.
On the Ford, if the plug was wet but did not smell like anything, this may be due to oil getting on the plugs. Have a compression test done on the cylinders to make sure you have good compression, and then have the injectors cleaned to make sure they are in good condition.
On the Nissan, you would need to supply the codes to help with a diagnosis. A misfire on these may be anything from shorted wires in the spark plug hole to oil leaking from the valve cover shorting the wires. Remove coils and see if they have oil on them. Replace the spark plugs, coil boots, and the valve cover gasket. You may want to check a fuel sample to see if you got water in the fuel if you happen to get fuel at the same gas station. Water on the plugs would also not have a smell. If you would like to have this checked, consider having a certified technician from YourMechanic, inspect the sputtering issue to have this addressed appropriately.
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