Question I have a 98 dodge ram 1500 5.9L360. Been having difficulty with the check engine light. Scan tool shows misfire on cylinder 8. Garage replaced intake gasket, new thermostat and gasket, replaced air filter, and no 8 spark plug as it had oil on it. The light is still periodically coming back on. We reset the light over month ago and it stayed off until 3 days ago. We reset it again and are hoping for the best. The truck runs good. What do i try now?
Answer Hi Barbara,
If the code is still for the number 8 cylinder missing (0308) then I would suspect, based upon the oil build-up on the plug, that there is either a worn valve guide or piston ring on that cylinder. Either of those would be expensive to repair.
What weight of engine oil are you using? One thing to try would be to increase the weight of the oil one step at the next oil change as that would reduce the in-flow of oil into the cylinder and prolong the running time before the plug gets oiled-up again.
Other than that, you could 'live' with the light/miss until it becomes a problem with the actual performance of the engine. Just periodically check the code, which you may be able to do using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see if the mileage reading is replaced by a 4-digit number preceded by a P which would be the fault code involved in the light being 'on'. That self-readout may or may not be available in your truck, but give it a try.
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