Hi, 1997 Chevy K1500 5.7L V8 here with a misfire on cylinder 4. I've replaced distributor cap, rotor, wires and spark plugs and nothing improved. Spark is good. Changed out the spider injector and used a "pop-it" light to check that a signal is being sent into the spider injectors. All is good. O2 sensors are new. Both catalytic converters are 2 years old. What gives?
My car has 190000 miles.
My car has an automatic transmission.
If both fuel and ignition are good, then it may be a mechanical issue with cylinder #4. A compression test may be a route to take. Considering the age and mileage, a worn intake or exhaust valve, or possibly valve seats can be allowing compression to leak past and cause a misfire. It can also be a "sticking or lazy" valve lifter. If the #4 valves are not opening/closing in proper time, this can also cause a misfire.
Have a car question? Get free advice from our top-rated mechanics.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing