Help Please!!

Im working on a 4cyc Camry. the timing is correct, cam and crank shaft regulators OHM correctly also the coil/ignitor they also OHM correctly. it turns over and then backfires. theres gas and new spark plugs. the #4 cyc maybe weak. what is the problem? any input would be greatly apprecaited. thanks

any one??

Try posting in > Cars in General > Engineering/Technical. It sounds like one of your plugs is not getting a spark.